HOSA 2

Lymphocyte Production

• Lymphocytes are found in blood, lymph, and lymphoid tissues and are the "cornerstone" of the immune system.

• Lymphocytes differentiate into B cells and T cells before detecting foreign invaders.

  • T lymphocytes protect against viral infections and destroy some cancer cells.

  • B lymphocytes develop into cells that produce antibodies (plasma cells).

B Lymphocytes 🦠

• Stem cells in bone marrow produce and mature B lymphocytes.

• B cells produce antibodies after maturation.

• Exposure to an antigen activates B cells to enlarge and multiply, creating clones.

• Most clones become plasma cells that produce specific antibodies, leading to humoral immunity.

• Macrophages engulf and destroy antigens after antibodies identify them.

B Lymphocytes Continued

• Clones that don't become plasma cells remain as memory cells.

• On repeated exposure to an antigen, memory cells immediately produce antibodies.

• This "immunologic memory" can make a person immune to reinfection.

• B lymphocytes are predominantly in organized lymphoid tissues like the spleen, making up 10%-20% of circulating lymphocytes in the blood.

Antigens and Antibodies 🧬

Antigen (Ag): Any foreign substance or molecule that stimulates an immune response.

• Most antigens are large protein molecules found on the surface of foreign organisms, RBCs, tissue cells, pollen, and toxins.

• Some carbohydrates and lipids can also act as antigens.

Antibody (Ab): A protein substance produced in response to an antigen.

• B lymphocytes produce antibodies.

• All antibodies are in the gamma globulin fraction of blood plasma, also called gamma globulins or immunoglobulins (Ig).

Immunoglobulins (Antibodies)

ImmunoglobulinFunctionIgMStimulates complement activity; produced on initial exposure to an antigen.IgGProtects the fetus before birth against antitoxins, viruses, and bacteria; most common antibody, produced on second and future exposures to an antigen.IgAProtects mucosal surfaces; found in secretions like saliva, tears, and bronchial fluids; important for defense against microbes entering through mucous membranes.IgEResponsible for immediate-type allergic reactions; helpful in fighting parasitic infections.IgDBelieved to function as an antigen receptor.

Each antigen stimulates the production of its own specific antibody. The body can make about 1 million individual antibodies. Antibodies label antigens for destruction by other substances.

T Lymphocytes 🦠

• Immature stem cells from the bone marrow migrate to the thymus gland to become T cells.

• T cells make up 80%-90% of lymphocytes in circulating blood.

• In the thymus, T cells proliferate and become sensitized to specific foreign antigens, leading to cell-mediated immunity.

• T lymphocytes fight cancer cells, viruses, and intracellular parasites and differentiate between "self" and "non-self".

T Lymphocytes Continued

• T cells can cause tissue or organ rejection after transplantation because they recognize transplanted tissues as "non-self."

• Anti-rejection medications are used to neutralize this response.

• Several types of T lymphocytes exist, each with its own function.

• Antigens must be presented to T cells on the surface of a macrophage.

• Macrophages release interleukins that stimulate T-cell growth.

Helper T Cells

• Helper T cells regulate innate and adaptive immune responses.

• They instruct other cells to kill infected cells or pathogens.

• Activation requires multiple receptors on the helper T cell to bind to specific antigens.

• They release cytokines, which help macrophages and increase killer T cells.

• They also help activate antibody-producing B cells.

Killer T Cells

• Killer T cells (cytotoxic T cells) kill cells infected with pathogens or otherwise damaged.

• They search for cells with a specific antigen on their receptors.

• Killer T cells release perforin, a cytotoxin that forms pores in the plasma membrane of target cells, causing osmotic lysis and cell death.

• Killer T cells can be activated when bound to a single antigen molecule.

Natural Killer (NK) Cells

• Natural killer (NK) cells are larger lymphocytes that are considered "non-specific" in immune response.

• They kill certain microbes (particularly viruses) and cancer cells without requiring the maturation of B and T cells.

• They are part of the body's natural defense against cancer.

• NK cells also secrete some cytokines.

Cytokines

Cytokines are proteins that act as messengers to regulate the functions of lymphocytes and macrophages during the immune response.

CytokineFunctionInterferon-alphaUsed to treat certain cancers, such as hairy cell leukemia.Interferon-betaBelieved to be helpful in multiple sclerosis.Interleukin-1Produced by macrophages, mobilizes T lymphocytes.Interleukin-2Produced by T cells, stimulates production of interferon; used to treat cancers but has adverse effects.Interleukin-3Required for differentiation of certain T cells.Interleukin-8Guides neutrophils to the source of an antigen.Interleukin-12Stimulates natural killer cells.Granulocyte colony-stimulating factorUsed to increase neutrophils in clients undergoing chemotherapy.

Primary Lymphoid Organs

In addition to the bone marrow, the thymus is a central or primary lymphoid organ.

• It is located in the mediastinum of the upper chest.

• The thymus is most active early in life and begins to atrophy at puberty.

• T lymphocytes mature in the thymus gland in children (and in other lymphoid tissues in adults) before performing immune functions.

• The thymus produces hormones called thymosin, thymic humoral factor (THF), thymic factor (TF), and thymopoietin, which promote the proliferation and maturation of T cells.

Peripheral Lymphoid Organs

Peripheral or secondary lymphoid organs include lymphoid structures scattered in the submucosal layers of the respiratory, gastrointestinal, and genitourinary tracts, as well as the tonsils, lymph nodes, and spleen. These organs filter tissue fluid or lymph for foreign particles and microorganisms.

Mononuclear Phagocyte System 🦠

The mononuclear phagocyte system, or reticuloendothelial system, consists of specialized cells throughout the body that ingest foreign particulate matter.

• These cells begin as monocytes and transform into macrophages after entering tissues via the bloodstream.

• The system destroys worn-out blood cells, bacteria, cancer cells, and other dangerous foreign substances.

• Some macrophages have special names, such as Kupffer cells in the liver sinusoids and dust cells in the lungs.

• Mononuclear phagocytes play a role in both specific and non-specific immunity, capturing, processing, and presenting antigens to lymphocytes for destruction.

• The macrophage-bound antigen triggers the humoral or cell-mediated immune response when presented to B or T lymphocytes.

Non-Specific Defense Mechanisms 🛡

Non-specific defense mechanisms fight against a variety of foreign invaders.

• Skin: Provides a physical barrier and secretes enzymes that kill or reduce the virulence of bacteria.

• Mechanical Reactions: Coughing or sneezing helps remove pathogenic material.

• Chemical Barriers: Normal flora of the GI system neutralizes or kills microorganisms.

• Tears: Dilute and wash away irritating substances and microbes.

• Cellular Barriers: Neutrophils, dendritic cells, and monocytes ingest and destroy bacteria and toxins and remove cellular debris.

• Macrophages: Live in tissues and produce enzymes and other chemicals; neutrophils are the most common macrophages.

• Chemotaxis: Process by which neutrophils go to the site of inflammation and are the first to arrive.

• Antigen-Presenting Cells: Neutrophils and macrophages activate the adaptive immune system and clean out debris from the infection.

• Interferon: A protein made by several types of cells, inhibits virus production and infection.

• Fever and Inflammation: Intensify the effects of interferons, inhibit the growth of some microbes, and speed up body reactions, aiding in tissue repair.

• Respiratory Tract: Cilia and macrophages in mucous membrane lining trap and remove microbes and dust; hairs in the nose also serve as a mechanical barrier.

• Stomach: Contains hydrochloric acid, which destroys pathogens taken in with foods.

• Other Substances: Earwax, mucus, vaginal secretions, and semen provide some protection against pathogens.

• Expulsion: Vomiting, defecation, and urination expel microbes from the body, along with normal waste products.

Specific Defense Mechanisms

• Specific defense mechanisms recognize and respond to specific foreign substances.

• Cellular defenses include humoral immunity, which occurs quickly when lymphocytes recognize a foreign substance, and cell-mediated immunity, which occurs more slowly and depends on T lymphocytes.

• Specific immunity is classified into inborn and acquired.

Inborn Immunity

Inborn immunity is inherited or genetic and may be common to all members of a species, a specific population, sex, ethnic group, or individual person.

Acquired (Adaptive) Immunity

Acquired or adaptive immunity is attained through natural or artificial sources and can be active or passive.

Naturally Acquired Immunity

Naturally acquired immunity occurs when a person is not deliberately exposed to a causative agent.

• Naturally acquired active immunity: Results when a child is exposed to and develops a disease (e.g., measles or chickenpox) and builds up antibodies to infections caused by the same organism. The body also manufactures memory cells.

• Naturally acquired passive immunity: Occurs between mothers and their infants; immunity is transferred from mother to fetus during pregnancy via the placental circulation exchange. The baby also receives protection after birth through the mother's breast milk. It can last to 6 months of age, when the infant's own immune system begins to take over (antibodies are "borrowed" from the mother).

Artificially Acquired Immunity

Artificially acquired immunity occurs when a person is deliberately exposed to a causative agent.

• Artificially acquired active immunity: Occurs through an injection of the causative agent (antigen) into the person's system (vaccination, inoculation, or immunization). The causative agent is diluted to reduce its virulence, so the recipient will form antibodies without becoming ill.

• Artificially acquired passive immunity: Occurs with the injection of ready-made antibodies into a person's system (produced by another individual's immune system). Examples include immunization for rabies or tetanus toxoid. Immunoglobulin IgG (gamma globulin) can also be injected after disease exposure for short-term immunity.

Antigen-Antibody Reaction 🧪

• Antigen-antibody reactions begin with B lymphocytes, which produce humoral immunity.

• Humoral immunity is the body's resistance to circulating disease-producing antigens and bacteria.

• B cells become plasma cells and produce antibodies.

• Antibody-mediated immunity changes an antigen, rendering it harmless to the body.

• The antibody binds to the antigen, forming an antigen-antibody complex (like a "lock-and-key" mechanism).

• The antibody can neutralize the antigen's toxins or cause harmful cells to clump together for destruction by macrophages and phagocytes.

Complement System

The complement system attacks the surface of an antibody-coated foreign cell, helping the antibodies to kill the pathogen. This is called complement fixation.

• A complement is a group of normally inactive proteins in the blood.

• The complement combines with the antigen-antibody complex and helps attack invading antigens.

• When activated, complements cause the formation of specialized antigen-antibody complexes that target specific cells.

• Killer T cells release cytotoxins, causing pores in cell membranes, allowing water and sodium to flow into the cells, causing them to burst and be destroyed.

Immune System Disorders

• Immune system disorders are increasingly identified and believed to cause many other disorders.

• Remaining calm and unstressed may reduce the likelihood of autoimmune disorders.

Effects of Aging on the Immune System 👵

• Older adults have fewer T cells and B cells, and those remaining function poorly.

• The immune system acts with a slower, muted inflammatory process and response to infection.

• Older adults may have a lower baseline body temperature (below 98.6F) and may not always have a febrile response to infection.

Respiratory System 🫁

Introduction

The respiratory system draws air into the lungs, exchanges oxygen for carbon dioxide, and removes carbon dioxide and other gaseous wastes.

• The lungs depend on the cardiovascular system for gas exchange and oxygen delivery.

• Respiration includes ventilation (breathing), gas exchange (in the alveoli of the lungs and in the cells of the body), and oxygen and carbon dioxide transportation.

• Inhaled air is approximately 21% oxygen and 0.4% carbon dioxide, while exhaled air is approximately 16% oxygen and 4.5% carbon dioxide.

• The respiratory system depends on the circulatory system to transport gases and on the nervous system to receive stimuli at the brain's respiratory centers to initiate and control respirations.

Upper Respiratory Tract

The upper respiratory tract consists of the nose, sinuses, pharynx, larynx, and trachea. These structures serve as pathways for air to enter and exit the lungs.

• Air enters through the right and left external nares or nostrils.

• The nasal septum divides the internal nose into two cavities.

• Nerve endings in the septum and nasal passages are responsible for the sense of smell, carried to the brain by the olfactory nerve (cranial nerve I).

• Mucous membrane, richly supplied with blood vessels, lines the nasal cavity to warm and moisten air.

• Sticky mucus traps dust particles, dirt, and microorganisms.

• Hairs at the nostrils and cilia (tiny hair-like projections) on the membranes filter foreign particles.

• Cilia channel mucus from the upper respiratory tract into the throat, where it is swallowed into the digestive system and destroyed by hydrochloric acid.

• Three small bones, the turbinates or conchae, project into the nasal cavity to increase the surface area of the mucous membrane.

🌬 Warming and Filtering Air

The respiratory system is responsible for warming and filtering air. Here's a breakdown of its key components:

Nasal Cavities

• Nasolacrimal ducts (tear ducts): Open into the upper nasal cavities, providing lubrication and causing a runny nose when crying.

• Cartilage: Present from the nose to the small bronchi.

Sinuses

• Four pairs of sinuses (eight total) located on each side of the nasal area.

• Lined with mucosa continuous with the nasal mucosa.

• Functions:

  • Lighten the skull.

  • Provide resonance for the voice.

• Named after the facial bones where they are located:

  • Frontal sinuses: Above the eye sockets.

  • Maxillary sinuses: In conjunction with the maxillary bone, on each side of the nose.

  • Ethmoidal sinuses: Between the eyes.

  • Sphenoidal sinuses: On each side of the nasal cavity, in the area of the orbit (eye socket).

咽 Pharynx

The pharynx is a tube-shaped passage for both air and food. It has three sections:

• Nasopharynx:

  • Extends from the nares (nostrils) to the uvula.

  • Passageway for air only.

  • Contains the adenoids (pharyngeal tonsils) in childhood.

    • Assist in the immune response.

    • Enlargement can cause snoring or airway obstruction.

    • Usually atrophy in adulthood.

  • During swallowing, the soft palate and uvula block the nasal cavity to prevent food from entering the respiratory system.

  • Auditory (Eustachian) tubes: Connect the nasopharynx with the middle ear.

    • Permit air to enter or leave the middle ear, allowing proper function of the eardrums and equalizing pressure.

• Oropharynx:

  • Extends from the uvula to the epiglottis.

  • Commonly called the "throat."

  • Carries food to the esophagus and air to the trachea.

  • Contains two sets of tonsils:

    • Palatine tonsils: Located posteriorly, on each side of the oral cavity; commonly removed during a tonsillectomy.

    • Lingual tonsils: Located at the base of the tongue.

  • The tonsils, along with the adenoids, play a role in the immune system by destroying foreign substances inhaled or ingested.

• Laryngopharynx:

  • Lowest portion of the pharynx.

  • Extends from the epiglottis to its division into the larynx (for air) and the esophagus (for food).

喉 Larynx

The larynx is a box-like structure made of cartilages held together by ligaments, ensuring the airway remains open.

• Thyroid cartilage (Adam's apple): The largest and most prominent cartilage, especially in males.

• Located in the midline of the neck.

• Function: Air passageway between the pharynx and the trachea; only air is allowed to pass into the larynx.

• Epiglottis: A lid or cover of cartilage that guards the entrance to the larynx.

  • Closes automatically when swallowing, preventing food from entering the lower respiratory passage. Metaphorically referred to as "trap door cartilage".

• Glottis: Vocal structure of the larynx, consisting of the true vocal cords and their related openings.

• Vocal cords (vocal folds): Two thin, triangle-shaped, reed-like folds within the larynx.

  • Attached to the front wall of the trachea and a tiny cartilage near the back wall.

  • Can move to produce sounds or allow silent breathing.

  • Vibrate when air leaves the lungs and passes over them, producing sound. This is analogous to a reed organ.

  • The size of the vocal cords and larynx varies, accounting for differences in voices.

  • A larger larynx results in a deeper voice.

🫁 Trachea

The trachea is a tube approximately 4.5 inches (11 cm) long and 1 inch in diameter in adults.

• Composed of C-shaped hyaline cartilage and connective tissue.

• Extends from the lower end of the larynx into the chest cavity behind the heart.

• Function: Air passes from the larynx into the trachea.

• Horseshoe-shaped cartilaginous rings provide rigidity to keep it open for air passage.

• Rings are flexible enough to permit bending of the neck.

• At the bottom, the trachea branches.

• Ciliated mucous membrane lines the trachea.

  • Mucus traps inhaled foreign particles.

  • Cilia carry the particles out of the respiratory tract through the pharynx.

• Smooth muscles assist in air passage.

• The esophagus, which transports food from the pharynx to the stomach, is located immediately posterior to the larynx and trachea.

🌳 Bronchi and Bronchial Tree

• As the trachea enters the chest cavity, it divides into two smaller tubes called the bronchi.

• Hilum: An indented area where each bronchus enters the lung and branches off. Arteries, veins, and nerves also enter the lungs at the hilum.

• One primary bronchus enters each lung.

  • The right bronchus is shorter, straighter, and wider than the left bronchus.

• Within the lungs, the cartilage in the small bronchi exists as interspersed plates rather than rings.

• The bronchi and bronchioles are encircled by smooth muscles, and there is more elastic tissue.

• Bronchial tree (tracheobronchial tree): Formed as each bronchus continues to divide into smaller branches.

• As the bronchi become smaller, their walls become thinner, the amount of cartilage decreases, and they become known as bronchioles.

• The bronchi and bronchioles continue to be lined with ciliated mucous membrane.

• The bronchioles branch into alveolar ducts, which end in many alveolar sacs.

• Each lung contains millions of alveoli.

  • Microscopic "balloons" that give the lungs their spongy appearance.

  • Walls are composed of a single layer of cells.

  • Lined with surfactant, a chemical that helps prevent the alveolar walls from collapsing between breaths.

Surfactant

• Substance secreted by the great alveolar cells (type II cells) of the lungs.

• Mixture of phospholipids (special type of fat that also contains phosphorus).

• Main phospholipids: Lecithin and sphingomyelin.

• Function:

  • Reduces surface tension in the pulmonary fluids. Analogous to laundry detergent breaking up dirt and grease particles.

  • Preserves the elastic property of lung tissue.

  • Prevents collapse of the alveolar walls between breaths.

🫁 Lungs

Humans have two cone-shaped lungs that fill the chest cavity.

• Function: Where oxygen is delivered from the outside air and carbon dioxide is removed.

• Apex: The top of each triangular cone.

• Base: The lower, wide portion that fits over the diaphragm.

• Cardiac notch (cardiac impression): An area on each lung, much larger and deeper on the left due to the heart's position.

• The lungs are composed of spongy tissue filled with alveoli, nerves, and blood and lymph vessels.

• They are separated by the heart, large blood vessels, the esophagus, and other contents of the mediastinum, the area lying between the lungs in the thorax (chest).

• The lungs are divided into sections called lobes.

  • The right lung has three lobes.

  • The left lung has two lobes.

😮‍💨 Breathing

Mechanics of Breathing

• Normal breathing results from nervous stimulation of the respiratory center in the brain's medulla.

• The lungs cannot move by themselves; actions of surrounding muscles inflate and deflate them.

• The medulla sends impulses to the diaphragm and intercostal muscles.

• Diaphragm: A dome-shaped muscle separating the thoracic and abdominal cavities.

  • Contraction and flattening increases the chest (pleural) space and pleural vacuum.

• Intercostal muscles: Located between the ribs.

  • Contraction lifts and spreads the ribs during inhalation, adding to the vacuum.

• Air moves from the external to the internal environment due to pressure differences between the atmosphere and the chest cavity.

• Inspiration: Chest cavity increases in size, creating an internal vacuum. Air enters the lungs when the intrathoracic pressure is below atmospheric pressure.

• Expiration: A passive process where the chest wall and lung muscles relax.

  • The thoracic cavity becomes smaller due to the relaxation of diaphragm and intercostal muscles.

  • Air rushes out when the intrathoracic pressure rises above atmospheric pressure.

  • The reduced size of the thoracic cavity and natural elasticity of the lungs force air out.

Control of Breathing

• The medulla's respiratory center automatically controls the depth and rate of respirations without conscious thought.

• The pons has centers that work with the medulla to produce a normal breathing rhythm.

• The cerebral cortex allows some voluntary control over breathing when talking, singing, eating, or changing the rate of breathing.

• Chemoreceptors in the medulla stimulate the muscles of respiration primarily in response to changes in carbon dioxide levels.

• Carbon dioxide, not oxygen, is the major regulator of respiration.

• Lung capacity varies with sex, size, physical condition, and age.

• Pulmonary diseases and other conditions that limit chest cavity expansion greatly influence a person's comfort and ability to survive.

Types of Respiration

• External respiration (pulmonary respiration): Exchange of oxygen (O2) for carbon dioxide (CO2) within the alveoli of the lungs.

  • Involves the external environment.

• Internal respiration (cellular respiration): Exchange of oxygen (O2) for carbon dioxide (CO2) within the cells.

Gas Exchange

• An increase in carbon dioxide levels stimulates respiration.

• Carbon dioxide and water are the waste products of respiration.

• Non-oxygenated blood from the right ventricle of the heart flows into the pulmonary artery, which branches into right and left segments.

• Further branching leads to pulmonary and bronchial capillaries in the lungs, where gases (oxygen and carbon dioxide) are exchanged via diffusion through the alveoli.

• The walls of the alveoli are made up of one cell-layer of epithelial cells (approximately 0.2 μm).

• Alveoli are surrounded by equally thin capillaries, a single endothelial cell thick.

• Extensive branching of pulmonary blood vessels leads to low pressure within the vessels, facilitating gas exchange.

• Oxygen travels through the walls of the alveoli into the capillaries and binds to hemoglobin in red blood cells.

• Small veins collect the oxygenated blood from the lung capillaries.

• These veins combine into four pulmonary veins (two left, two right), which pour oxygenated blood into the left atrium of the heart.

• The blood in the left atrium is pumped through the left ventricle and through the aorta to the rest of the body.

• Oxygen-hemoglobin bonds are easily broken in tissues, releasing oxygen.

• At the same time oxygen is diffusing into the capillaries, the capillaries are giving up carbon dioxide back into the alveoli.

• Carbon dioxide, a waste product of metabolism, is transported by the blood from the body's cells to pulmonary capillaries in three main forms:

  • Dissolution in plasma.

  • In combination with proteins.

  • By formation into bicarbonate (HCO3) ions in the blood.

• Bicarbonate ions undergo a chemical change which yields carbon dioxide (CO2) and water (H2O).

• During exhalation, this carbon dioxide and some of the water are released from the lungs into the air.

⚖ pH Regulation

• The primary function of the respiratory system is the exchange of gases, and another important function is the regulation of the pH of all body fluids.

• The respiratory and renal systems interact to maintain homeostasis.

• Carbon dioxide can alter pH because it reacts with water to form carbonic acid (H2CO3H2​CO3​).

• Carbonic acid can break down to form H+ and HCO3 (hydrogen ion and bicarbonate ion).

• These ions are important to the buffer system, which helps the body maintain proper pH levels.

• The hydrogen ion often combines to form acids, such as hydrochloric acid (HCl).

• The bicarbonate ion often combines to form basic compounds, which counteract acids.

• One such base compound is sodium bicarbonate (NaHCO3NaHCO3​), also known as baking soda.

🛡 Protective Reflexes

• Coughing and sneezing: Protective reflexes needed to dislodge materials from the respiratory passages.

  • The bronchi and trachea have sensory receptors that initiate a cough in response to foreign particles or irritating substances.

  • The sneezing reflex is similar to coughing, except that the source of irritation is in the nasal passages.

• Yawning: A respiratory reflex believed to be a response to a lack of oxygen or an accumulation of carbon dioxide.

  • Equalizes pressure between the middle ear and the outside atmosphere, helping a person to maintain balance and reducing discomfort when flying or deep-sea diving.

• Sigh: A deep breath taken on occasion. Mechanical ventilators are often programmed to deliver a sigh breath on a regular basis to increase the client's comfort.

🗣 Phonation

• The movement of gases through the mouth, larynx, and pharynx allows a person to speak (phonate) or sing.

• Phonation is caused by the passage of air over the vocal cords in the larynx, causing vibrations, similar to the vibrations of the reed in an organ or clarinet.

• These vibrations are modulated by the person into speech or singing.

👴 Aging

• The organs of the respiratory system lose some elasticity with age.

• The chest walls become stiffer, and the lungs cannot expand as much; therefore, less air is exchanged with each breath.

• The ratio of the pressures of oxygen and carbon dioxide in the lungs may change, causing difficulties in blood oxygenation and exchange of oxygen for carbon dioxide at the cellular level.

• The changes of aging can also make the older person more susceptible to respiratory disorders, such as pneumonia.

• This susceptibility occurs not only as a result of decreased elasticity of the lungs and bronchioles but also because of decreased ciliary action and the decreased secretion of mucus in respiratory tract linings.

• Inactivity can lead to a number of respiratory disorders; pneumonia is a common result.

🍔 Digestive System: Structure and Function

Overview

• The body needs a constant supply of energy to perform its many tasks.

• The digestive system converts the food eaten into fuel for the body's energy demands.

• In a lifetime, the human digestive system will process about 50 tons of food!

Digestion and Absorption

• Digestion: The mechanical and chemical breakdown of food into usable materials for energy. It is a form of catabolism.

• Absorption: The process of transferring these food elements into the circulation for transport.

• After absorption, the elements are carried to the body's cells to be used for energy and building cells, an example of anabolism.

• The digestive tract, also called the alimentary canal, gastrointestinal (GI) tract, or GI system, is the efficient food-processing machine responsible for digestion and absorption.

• The specialty concerned with the study of the stomach and intestine is gastroenterology.

• The GI tract or canal is like a tube, approximately 28-30 feet (9.1 m) long; it runs through the body and is open to the outside at both ends (mouth and anus).

• Food travels through the GI tract in about 24-36 hours.

• The final stage of digestion is elimination (egestion, defecation).

• The actions of the digestive system are controlled by the nervous system. The endocrine system also exerts a major influence.

• Elements broken down by digestion to provide fuel for the body are called nutrients. These nutrients are carbohydrates, proteins, and fats. They consist of carbon, hydrogen, and oxygen; proteins also contain nitrogen.

👄 Mouth (Oral Cavity)

• Food is taken into the body through the mouth, where digestion begins. This is called the cephalic phase of digestion.

• Here, the teeth cut, chop, and grind food so the food particles become smaller and more of their surface can be exposed to the actions of digestive juices and enzymes.

• The mouth's chief digestive functions are to receive food via ingestion (to take in), to prepare food for digestion, and to begin the digestion of starch.

• The roof of the mouth is made up of the hard and soft palates.

  • The hard palate is close to the front of the mouth and is composed of the palatine bones and parts of the maxillary bones.

  • The soft palate is mostly muscle tissue. It separates the mouth from the nasopharynx.

• The soft palate is shaped like an arch in the back of the mouth and opens onto the oropharynx.

• The structure that can be seen suspended in the back of the open mouth is the uvula.

• The tongue covers the floor of the mouth.

• The walls of the mouth cavity are the cheeks and the teeth.

Salivary Glands

• When a person sees or thinks about food, the salivary glands begin to function, making the "mouth water."

• Three pairs of salivary glands pour 1-1.5 L of saliva into the mouth each day.

• The names of these glands indicate their locations:

  • Sublingual: Under the tongue.

  • Parotid: Cheek.

  • Submandibular: Under the lower jaw.

• The salivary glands are exocrine glands because their secretions are not directly released into the circulation but are released into the oral cavity.

• Two types of saliva:

  • Thin and watery: wets the food and makes it easier to swallow.

  • Thicker, mucous secretion: contains mucin, which lubricates and also causes food particles to stick together to form a bolus (ball or lump) of food.

• Saliva contains ptyalin, also called salivary amylase.

• Saliva also contains water, mucus, and salts.

• The nervous system controls the secretion of saliva (salivation).

• Through the action of ptyalin, saliva begins to break down starch (polysaccharides) into smaller sugar molecules.

• Saliva helps prevent oral infections because it contains lysozymes (bacteriocidal enzymes) and immunoglobulins (IgA).

• The pH of saliva is normally about 6.8 (very weak acid).

• Saliva also assists with speech and taste.

Teeth

• The teeth are set in spaces or sockets in the upper and lower jaw bones—the maxilla and mandible.

• The chief function of teeth is to break food into smaller particles, which is accomplished through mastication, the act of chewing.

• Humans have two sets of teeth: the deciduous ("falling out") or "baby teeth" and a permanent or adult set.

• A baby's deciduous teeth usually begin to erupt between 6 and 8 months of age, and the teeth are usually complete by 30 months of age.

• At the age of about 6 years, children's permanent teeth begin to appear.

• As the permanent teeth grow in, they push out the deciduous teeth, replace them, and fill in the spaces in the jaw. The permanent set has 32 teeth.

Types of Teeth

Tooth TypeFunctionLocationIncisorsCut and tear foodFront teethCanines (Cuspids)Hold and tear foodSide teethBicuspids (Premolars)Crush and grind foodSide/Back teethMolarsCrush and grind foodBack teethWisdom TeethGrind FoodFar back of mouth

• The last permanent teeth, the third molars or wisdom teeth, sometimes do not appear before adulthood. They are located in the far back of the mouth.

• If a person's jaws are small and jaw space limited, the wisdom teeth may not have room to erupt and may become impacted in the bone or tissue.

• Impacted wisdom teeth often require surgical removal.

Tooth Structure

• A tooth has three parts: crown, neck, and root.

  • The crown is the enamel-covered part of the tooth visible in the mouth. (Tooth enamel is the hardest structure in the body.)

  • The tooth narrows into a neck at the gum line. (The gum is also known as the gingiva.)

  • The root of the tooth is in the bony socket. A substance called cement (or cementum) covers the root.

• Beneath the enamel and the cement is a hard bonelike substance called dentin, which is the bulk of tooth material.

• The tooth's center is the pulp cavity (pulp chamber). The pulp contains many nerve endings and blood vessels, which enter through the roots (via the root canal) from the tooth sockets.

• The teeth are embedded in and nourished by bone.

Tongue

• The tongue is a tough skeletal muscle covered with smooth mucous membrane.

• It is attached to four bones: the mandible, two temporal bones, and the hyoid.

• On the bottom of the tongue is a fold of mucous membrane called the frenulum. This structure helps to attach the tongue to the floor of the mouth.

• The tongue has several functions:

  • Senses the temperature and the texture of food.

  • Mixes food with saliva, and moves food into position to be chewed.

  • The voluntary movement of the tongue begins the swallowing process, called deglutition, by pushing food into the pharynx, the next portion of the digestive tube.

• The upper surface of the tongue appears rough because of visible indentations (fissures) and projections (papillae).

• The taste buds are microscopic nipple-like projections located on the sides of the papillae.

• They are specialized nerve endings that allow detection of various flavors.

• The taste buds distinguish among flavors. Although all types of taste buds are found on most areas of the tongue, they are concentrated as follows:

  • Salty: tip and sides of the tongue.

  • Bitter: back of the tongue.

  • Sweet: tip of tongue.

  • Sour: sides of the tongue.

  • Alkaline and metallic flavors are sometimes considered distinct flavors as well.

咽 Pharynx (Shared Passage)

• The pharynx is a passageway about 5 inches (12.7 cm) long, used for both food and air.

• Its areas are named in relationship to location.

  • The nasopharynx, which is located behind the nasal cavity, is lined with ciliated columnar pseudostratified epithelium.

  • The oropharynx lies behind the oral cavity (mouth) and is lined with stratified squamous epithelium.

  • The laryngopharynx (hypopharynx) has the same lining and is situated just below the epiglottis. In this area, the respiratory and digestive tubes divide.

• The larynx is located directly in front of the pharynx and is the structure through which air passes into the lungs.

• Because the larynx and pharynx are so close together, a special mechanism, the epiglottis, prevents aspiration of food and fluids into the lungs when a person swallows.

• This flap of tissue drops down to cover the larynx and trachea (windpipe) during swallowing. (Food has the "right of way" over air at this point.)

• In the mouth, the tongue lifts and moves the bolus of food, mixed with saliva. The initial swallowing of food is voluntary. The tongue pushes the bolus into the pharynx, where the movement becomes involuntary. (Here, the medulla's swallowing center takes over.)

• Contractions of the pharynx push food into the muscular esophagus.

• The entire digestive tract, including the pharynx, is lined with mucous membrane.

• The smooth (involuntary) muscles pass food through the entire GI tube by waves of contractions called peristalsis, an alternating relaxation and contraction of muscles.

• Two layers of smooth (involuntary) muscles are involved:

  • The outer layer of esophageal muscles runs up and down (longitudinal).

  • The inner layer lies in concentric circles.

• Digestion cannot occur without peristalsis.

🫕 Esophagus (Gullet)

• The esophagus, or gullet, is approximately 10 inches (25.4 cm) in length; it extends from the pharynx into the neck and thorax and, through an opening in the diaphragm, to the stomach.

• The role of the esophagus in digestion is to serve as a passageway.

• A strong circular muscle lies between the esophagus and stomach.

• This is the cardiac sphincter or lower esophageal sphincter (LES); sometimes called the gastroesophageal sphincter.

This sphincter guards the opening of the stomach by preventing food from backing up into the esophagus. As waves of peristalsis push food through the lower esophagus, the LES opens (allowing food to enter) and closes (to keep food in the stomach).

胃 Stomach

• Food begins the gastric or peptic phase of digestion when it enters the stomach (gaster), a C-shaped muscular, collapsible pouch or sac capable of being greatly distended (expanded).

• It has a volume of approximately 2/5 cup when empty but can expand to hold more than 8 cups after a meal.

• The stomach is located in the upper left side of the abdominal cavity and receives its blood supply from the celiac artery.

• Regions of the Stomach:

  • Fundus: The rounded portion above the level of the cardiac sphincter, in which is located the opening from the esophagus.

  • Body: The central and largest portion.

  • Pylorus: The lower narrow portion, which attaches to the small intestine. The walnut-sized pyloric sphincter controls the opening between the stomach and the duodenal portion of the small intestine. (The prefix referring to the stomach is gastr[o]-.)

• The outside of the stomach is covered by serous membrane.

• Next, is a thick pad of muscles. These muscles lie in three layers:

  • Longitudinal layer (muscle fibers going the long way, from top to bottom).

  • Center layer consists of muscle fibers that encircle the stomach.

  • Innermost is an oblique layer (muscle fibers on a slant or angle).

• The spread and action of these muscles stir and churn food, break it into small particles, and move it through the system.

• When the stomach is empty, it collapses and lies in folds called rugae. These rugae allow the stomach to distend greatly when food is eaten.

• Under the muscular layer of the stomach lies the submucosa. In this layer, connective tissues contain nerves, as well as blood and lymph vessels.

• The innermost layer of the stomach is the extensively folded mucosa, which is connective tissue covered with gastric glands.

• Hydrochloric acid (HCl, gastric acid) and pepsinogen (which leads to the enzyme, pepsin) are secreted here.

• In addition, this layer secretes mucus, which lubricates food and protects the lining of the stomach from the acids and other gastric juices.

• In the stomach, all foods mix with mucus and gastric acid, as well as pepsin and other digestive enzymes (about 3 quarts—2.8 liters a day). These substances churn until they are in a semi-liquid, milky form called chyme.

• This process usually takes 3-5 hours. (The parietal cells of the stomach also secrete intrinsic factor, which allows the body to absorb vitamin B12.)

• Peristalsis of the stomach muscles moves food toward the pyloric outlet.

• The pyloric sphincter at the lower opening of the stomach contracts to keep food in the stomach until it is thoroughly mixed.

Stomach and Small Intestine 🍎

Stomach Function

The pyloric sphincter relaxes to allow peristaltic waves to squirt food in small amounts into the small intestine. However, some small molecules, such as alcohol, can be directly absorbed into the bloodstream from the stomach. If the stomach is irritated or too full, reverse peristalsis can occur, forcing material back into the esophagus, leading to vomiting. Vomiting (emesis) involves reverse peristalsis combined with contractions of abdominal muscles and the diaphragm, forcing food out through the mouth.

Small Intestine Structure and Function

The intestinal phase of digestion begins in the small intestine, which is approximately 20 feet (6.1 m) long and 1.5 inches (3.81 cm) in diameter. Its prefix is enter[o]-. The areas of the small intestine are the duodenum, the jejunum (midsection), and the ileum (terminal section). The small intestine consists of the same tissue layers as the stomach, with the exception of oblique muscles.

The longitudinal and circular smooth muscles are antagonistic. The wave-like contractions of the circular muscles narrow the lumen, squeezing food onward. When the longitudinal muscles contract, the circular muscles relax, increasing the size of the lumen, allowing food to pass. These rhythmic waves constitute intestinal peristalsis.

Intestinal glands in the mucous membrane lining the small intestine secrete enzymes for the digestion of all foods. Intestinal enzymes are proteins that act as catalysts, promoting and speeding up chemical reactions without undergoing changes themselves. These enzymes break down carbohydrates, proteins, and fats into materials that cells can use.

To be absorbed by the blood:

• Carbohydrates must be in the form of monosaccharides (glucose, fructose, galactose).

• Proteins must be digested into amino acids.

• Fats must be converted to fatty acids and glycerol.

The small intestine has numerous secretions:

• Mucus: Lubricates and protects the intestinal wall lining from the acidic chyme and digestive enzymes.

• Cholecystokinin: A secreted hormone that stimulates the pancreas to secrete pancreatic juice and the gallbladder to contract, resulting in the release of bile.

• Secretin: Another hormone that influences the secretion of pancreatic juice by the pancreas.

Pancreatic juice contains bicarbonate ions (HCO3−HCO3−​), which combine with sodium ions (Na+Na+) to form sodium bicarbonate (NaHCO3NaHCO3​), a basic substance that neutralizes the acidic chyme.

The first portion of the small intestine is the duodenum. Its wall contains specialized cells and glands designed to secrete mucus, which helps protect the small intestine from the acidic chyme. As chyme enters the duodenum, more digestive juices are added. Bile, a greenish brown liquid manufactured by the liver and stored in the gallbladder, pours in through the common bile duct to emulsify fats in preparation for further digestive action.

Chyme travels through the remaining portions of the small intestine: the jejunum and the ileum. The jejunum is named so because, when dissected, the jejunum is almost always empty. The entire small intestine is lined with mucous membrane. Numerous lymph nodules are in the ileum, both solitary and grouped. Those grouped together are called aggregated lymphatic follicles or Peyer's patches.

Large Intestine 🚾

A sphincter-like muscle, the ileocecal valve, is located where the large and small intestines meet. This valve prevents the backflow of material to the small intestine and regulates forward flow. The large intestine is wider than the small intestine (approximately 2.5 inches or 6.35 cm in diameter) but only about 5 feet (1.5 m) long. It does not coil but lies in folds and is divided into the cecum, colon, and rectum.

Water reabsorption is the main function of the large intestine. Intestinal bacteria inhibit the growth of pathogens, and some produce vitamin K, which is necessary for blood clotting. Absorption of vitamins and minerals and the formation and defecation of feces are also functions of the large intestine.

The first portion of the large intestine is the cecum, a blind pouch about 2-3 inches (5-7.6 cm) long. The vermiform appendix is a small finger-like projection of the cecum with no known function. It has the same lymphoid tissue as tonsils and can become infected, a condition called appendicitis. The cecum and appendix are located in the right lower quadrant of the abdominal cavity.

The next and longest portion of the large intestine is the colon, a continuous tube classified into three areas:

• Ascending colon: Travels up the right side of the abdominal cavity.

• Transverse colon: Crosses to the left side in the upper part of the cavity.

• Descending colon: Goes down the left side into the pelvis.

The first two portions absorb fluids, salts, and vitamins, while the descending colon holds the resulting wastes. The sigmoid colon ends at the rectum and stores the feces until defecation (bowel movement) occurs.

Rectum and Anus

The rectum is about 5 inches (12.7 cm) long and terminates at the anal canal, the terminal portion of the large intestine, which is about 1-1.5 inches long (2.54-3.8 cm). Waste products are excreted (egestion) via the opening to the outside (anus), which is guarded by internal and external sphincter muscles. The external sphincter is under a person's control and can be consciously contracted and relaxed.

Accessory Organs ⚙

The accessory organs of the digestive system include the liver, gallbladder, pancreas, and peritoneum.

Liver

The liver is the body's largest glandular organ, lying just below the diaphragm in the upper right quadrant of the abdominal cavity. Its prefix is hepat[o]-. It receives its blood supply from the hepatic artery and is divided into two major and two minor lobes. The liver weighs about 3 pounds (1.36 kg) and resembles calf liver in color and texture. Only the brain is capable of more functions than the liver.

Major functions of the liver:

FunctionDescriptionAbsorption of bilirubinFrom the destruction of old red blood cells (RBCs)Detoxification of bloodRemoval of toxins or poisonsStorage of fat-soluble vitaminsVitamins A, D, E, K, and ironFormation of vitamin AStorage of vitamin B complexFormation of plasma proteinsAlbumin, prothrombin, globulinsSynthesis of ureaA waste product from protein anabolismStorage of glucoseAs glycogenFormation of triglycerides and cholesterolSecretion of bileSecretion of heparinAnticoagulantSynthesis of immunoglobulinsBreaking down of fatsLipidsStorage of fats and carbohydratesRegulation of amino acidsProduction of body heatStorage of minerals

The liver's main digestive function is the production of bile, which aids in fat digestion and absorption of fat and fat-soluble vitamins from the small intestine. The salts in bile emulsify fat (break fat into small droplets) so that digestive enzymes can act on fat more effectively.

Gallbladder

The gallbladder is a muscular sac 3-4 inches long (7.5-10 cm), resembling a small pear, located on the liver's undersurface. Its prefix is chole-. The gallbladder's main functions are to store and release bile as needed in the small intestine for fat emulsification.

The biliary apparatus is the system of passageways for the transport of bile from the liver to the gallbladder to the intestine. Cells within the liver manufacture bile, which flows through small ducts that join to form the hepatic duct. Bile flows down the hepatic duct and up into the cystic duct to the gallbladder for storage.

Cholecystokinin activates the gallbladder to release bile, which flows from the gallbladder through the cystic duct. The cystic duct then joins the hepatic duct to create the common bile duct. The common bile duct, in combination with the pancreatic duct, then empties into the duodenum at the major duodenal papilla.

Pancreas

The pancreas is a long, fish-shaped glandular organ about 6 inches (15 cm) long located behind the stomach. This organ functions as both an endocrine gland and an exocrine gland. As an endocrine gland, it secretes the hormones insulin, glucagon, and somatostatin into the bloodstream to help regulate blood sugar levels.

Its exocrine function is to produce pancreatic juice, which is accomplished by the acinar cells. The acinar cells secrete three main enzymes which assist in the digestion of specific nutrients:

EnzymeSubstrateProduct(Pancreatic) amylaseStarchTrypsinProtein(Pancreatic) lipaseFats-lipidsTriglycerides

Most pancreatic enzymes are produced in inactive forms and are activated in the small intestine, minimizing the risk of pancreatic self-digestion. In addition to the digestive enzymes, pancreatic juice also contains bicarbonate (HCO3−HCO3−​) and water. Bicarbonate ions combine with hydrogen ions to neutralize the hydrochloric acid in chyme. Pancreatic juice enters the duodenum through the pancreatic duct and is necessary for life.

Peritoneum

The peritoneum is a large sheet of serous membrane that covers and protects many abdominal organs. It also secretes a thin fluid (peritoneal fluid) that provides lubrication between its visceral and parietal layers. Folds of the peritoneum that provide support and protection to the intestines are called mesenteries. Some body structures, such as the kidneys, lie behind the peritoneum and are said to be retroperitoneal.

Digestion 😋

After food is broken down, absorption can occur. The body performs two types of digestion: mechanical and chemical.

Mechanical digestion is the physical breakdown of food caused by chewing and the movement of food in the digestive tract.

Chemical digestion is the breakdown of the chemical bonds in food with the addition of enzymes, acids, and water.

Most digestion occurs in the duodenum.

Enzymes are the driving force behind chemical digestion. They are secreted by the salivary glands, stomach, small and large intestines, liver, and pancreas.

The GI tract uses other fluids to lubricate, liquefy, and digest food. Mucus, formulated by the mucous membrane lining of the GI tract, lubricates food and protects the GI tract's lining from mechanical or chemical injury (from stomach acids). Water liquefies food, making it easier to digest and absorb, and participates in chemical reactions.

The fundus and body of the stomach act mostly as storage areas; the pylorus is the area that is primarily responsible for stomach digestion. Both mechanical and chemical digestion occur in the stomach. Saliva from the oral cavity continues starch digestion in the stomach, but carbohydrates are not fully digested there. Fat digestion continues in the stomach owing to lingual lipase, but only a very small amount is broken down in the stomach. Pepsin begins protein digestion in the stomach, but it is not completed there either.

The stomach is lined with mucous membrane, which coats and protects the stomach lining. The stomach lining also contains secretory cells called chief cells and parietal cells.

Cell TypeSecretionFunctionChief cellsPepsinogenPrecursor of pepsin, the enzyme needed to break down proteins; Gastric lipase breaks down triglycerides in butterfatParietal cellsHydrochloric acidActivates pepsinogen and kills most microorganisms in the stomach; Intrinsic factor is essential for absorption of vitamin B12StomachRegulatory hormonessuch as gastrin which stimulates the secretion of hydrochloric acid and pepsinogen, weakly stimulates the pancreas to secrete enzymes and the gallbladder to release some bile

Most digestion takes place in the small intestine. Cholecystokinin (CCK), a hormone, is secreted by the duodenum and jejunum in response to the presence of fat in the duodenum. CCK activates the gallbladder to release bile. Bile flows through the cystic duct into the common bile duct and is deposited in the duodenum. There, the action of bile breaks fat droplets into smaller particles. Bile also helps neutralize the acidic chyme and facilitates excretion of waste products, including bilin and bile acids. Cholecystokinin also stimulates the pancreas to secrete pancreatic juice, which is then changed into an active form in the small intestine.

Specific enzymes (amylase, trypsin, and lipase) in the pancreatic juice digest starch, protein, and triglycerides (fats), respectively. CCK also assists in the inhibition of digestive processes in the stomach.

Sucrase, maltase, and lactase enzymes secreted by the intestinal mucosa assist in the digestion of carbohydrates (CHO). Several protein enzymes called peptidases also assist in the digestion of proteins. When digestion is completed, the simplest form of these nutrients remains. These are amino acids (proteins), fatty acids (lipids), and monosaccharides-simple sugars (glucose, galactose, and fructose).

Absorption 💧

Absorption into the body occurs across the villi, the small finger-like projections of the small intestine, into the capillary network. To increase the surface area, villi also contain microvilli, microscopic folds of the cell membrane. One person's villi and microvilli could completely cover more than 2,000 square feet. The villi wave to keep food molecules thoroughly mixed with digestive juices. Approximately 85% of nutrients used by the body are absorbed through villi of the small intestine into the bloodstream for delivery to cells.

Amino acids are absorbed in the duodenum and jejunum; most fats are absorbed in the jejunum. Because the villi play such an important part in absorption, they are heavily supplied with capillaries. These capillaries carry nutrients, by way of the hepatic portal circulation, to the liver for further processing. The mechanisms of active and passive transport are those by which nutrients are absorbed into the circulation and then into the cells for their use.

Bile salts are important in forming micelles, which are colloid (glue-like) particles, most often arranged in a parallel chain. Micelles transport digested fats to the intestinal villi for absorption. Most fatty acids (long-chain) are transported this way, then absorbed into lacteals, and carried by lymph (the lymphatic system) to be used by the body. Lacteals are dead-end lymph capillaries within each villus that absorb fat-soluble nutrients. The substance in lacteals is called chyle. Fats eventually reach the bloodstream by way of the thoracic and right lymphatic ducts.

After food has been in the small intestine for about 4-6 hours, it passes into the large intestine. All that remains is water, electrolytes, and waste products. This accounts for about 1,500 mL of chyme per day. As the wastes (chyme) travel through the large intestine, the intestinal walls of the proximal colon absorb most of the remaining water (about 80%) back into the circulation. This mechanism helps to prevent dehydration. Water travels by osmosis, following the absorption of mineral salts, mainly sodium. After this reabsorption, only waste products remain. When these reach the end of the colon (the distal colon), they are called feces and are excreted out of the body as stool.

Metabolism ⚡

Metabolism is defined as "biotransformation," the total of all physical and chemical changes that occur within the body to maintain life. Physical conversions include chewing and breaking down food into smaller particles. Chemical conversions include the actions of enzymes, which alter food into chemically smaller substances. The liver is vital for metabolism. The two major categories of metabolism are catabolism and anabolism.

Catabolism is the breakdown of larger molecules into smaller ones. During catabolism, energy is often released.

Anabolism involves the synthesis of simpler substances to form new, organized substances that the body's cells can use.

Examples of anabolism include the synthesis of glycogen, triglycerides, or proteins (e.g., hemoglobin).

During catabolism, energy is released. This energy is synthesized into adenosine triphosphate (ATP).

ATP stores energy and uses it to drive all cellular processes that require energy.

ATP is vital to the process of anabolism. Basal metabolism refers to the minimum amount of energy (calories) the body requires to maintain baseline vegetative vital functions, such as breathing, body temperature, and circulation.

Defecation 💩

No enzymes are in the colon; therefore, little digestion occurs there. Whatever nutrients are not reabsorbed and sent to the portal (liver) circulation are eliminated. The process of eliminating solid intestinal wastes from the colon is called defecation, bowel movement, or egestion.

As water is reabsorbed, a plant fiber called cellulose, other undigested material, living and dead bacteria, and mucus remain. They mass together and pass into the rectum as solid or semisolid waste or feces (excrement, excreta). Mass movements or strong peristaltic waves in the colon initiate the defecation (evacuation) reflex.

As feces enter the rectum, they stimulate sensory nerve endings, causing a sensation of accumulating bulk. Peristaltic waves push the contents against the anal muscle as a signal for emptying the rectum. This defecation reflex continues, as parasympathetic-controlled nervous activity causes strong contractions. The internal sphincter relaxes and the pressure from peristalsis, along with pressure that is consciously exerted by the diaphragm and abdominal muscles, brings about defecation.

To expel feces, the external anal sphincter, a skeletal muscle, relaxes voluntarily. If the defecation reflex is ignored routinely, the impulse tends to die and constipation often occurs.

Aging and the Digestive System 👴

The digestive system often slows down with age. The secretion of digestive juices and peristalsis slow. The result is a decreased ability to "eat anything and everything." Indiscriminate eating may cause stomach upset, heartburn, nausea, or diarrhea.

In the aging person, more food is left undigested, and sometimes inadequate amounts of fluid are taken in, causing constipation. Seniors often do not have a daily bowel movement because they do not consume sufficient food and fluids or get adequate exercise. Ignoring the urge to defecate often causes constipation.

Lowered responsiveness to internal cues of hunger and thirst can contribute to inadequate intake of food and fluids. Changes in the oral cavity may make chewing difficult and slow digestion. Many older people have lost teeth, owing to accidents or tooth and gum disease, which often causes additional difficulty in chewing. Foods that can be comfortably eaten may be limited. A stroke or other physical disorder and decreased salivary functioning may also cause difficult chewing or swallowing. Some older adults are underweight secondary to various age-related changes.

Some "forget" to eat or cannot afford to buy healthy foods. Some older people are unable to prepare foods properly. The senses of smell and taste may be impaired, resulting in a lack of appetite.

Impaired digestion and absorption of nutrients often result from decreased secretion of gastric juices and intestinal enzymes, along with decreases in absorptive surfaces, villi height, and intestinal motility. Excessive laxative and antacid use may further contribute to reduced absorption of essential fat-soluble vitamins and/or cause serious electrolyte imbalance.

A person who has been overweight may tend to gain even more weight with age. Weight gain is partly a process of aging, as fatty tissue replaces muscle tissue. It is also a result of reduced exercise and poor diet. Weight gained in younger years now becomes very difficult to lose. However, reduced efficiency of the digestive system may offset weight gain to some extent.

Urinary System 💧

As the body builds and repairs tissues and produces energy for life processes, waste products form that must be removed. Through the activities of perspiring and breathing, the integumentary and respiratory systems remove some water, carbon dioxide, and nitrogenous wastes. Through defecation, the digestive system removes the bulk of food wastes. Another system, the urinary or excretory system, is also involved in waste removal.

Circulating blood carries wastes from the cells to the kidneys for urinary elimination. Consequently, the urinary system is sometimes called the body's "filtration and removal plant." Uro- is the word element referring to urine.

The major structures of the urinary system:

• Two kidneys extract wastes from the blood, balance body fluids, and form urine.

• Two ureters conduct urine from the kidneys to the urinary bladder.

• The urinary bladder serves as a reservoir for urine.

• The urethra conducts urine from the bladder to the outside of the body for elimination.

The urinary system is able to adapt to wide variations in dietary and fluid intake. It also adjusts and maintains the composition of blood, tissue fluids, and interstitial fluids.

The volume of circulating fluids in the bloodstream affects blood pressure. The urinary system helps control blood volume by excreting or conserving water. By excreting or conserving minerals (especially sodium and chlorine) as necessary, the urinary system regulates specific levels of electrolytes in body tissues and fluids.

Kidneys

The kidneys are two reddish-brown, bean-shaped organs located in the small of the back at the lower edge of the ribs on either side of the vertebral column. They are about the size of a human fist (about 4 inches [10 cm] long, 2 inches [5 cm] wide, and 1 inch [2.5 cm] thick. On top of each kidney is an adrenal gland. The kidneys are said to be retroperitoneal because they lie behind the peritoneum. Kidney location is important because it enables kidney surgery to be performed from the back, without entrance into the abdominal cavity. The right kidney is slightly lower than the left because the liver takes up space on the body's right side. A person can easily live with one kidney. Ren- is the prefix related to kidneys; renal is the descriptive term used. The word element referring to the kidney is nephr(o-).

The kidneys are extremely vascular (heavily supplied with blood vessels). Blood supply is necessary so the kidneys can do the essential work of waste removal. Every day, approximately 10% of circulating blood in the entire body circulates through the kidneys. Each kidney is surrounded by peri-nephric (around the kidney) fat and is surrounded by a fibrous capsule.

On the medial surface of each kidney (toward the middle of the body) is an indented area called the hilum, a notch through which the blood vessels, nerves, and ureter enter.

The kidneys can precisely regulate and adjust electrolyte levels. By regulating sodium chloride (NaCl) levels, they control the volume of body fluids. They balance pH in the blood, body fluids, and within body tissues. The kidneys do this by eliminating acids directly into the urine or by excreting acids bound to chemical buffers. These buffers change strong acids into weaker acids, which enables the kidneys to excrete large amounts of acid without dramatically altering (or lowering) urine pH. However, urine is 1,000 times more acidic than blood. Other major functions of the kidneys include hormonal secretion of renin and erythropoietin and activation of vitamin D.

If the kidney is cut in half longitudinally, you can see that it is divided into two parts: the outside called the cortex and the inner portion called the medulla. The renal cortex is the outer reddish-brown part of the kidney that extends from the outside of the kidney (renal capsule) to the bases of the renal pyramids and into the spaces between them. The renal corpuscles (glomeruli and Bowman's capsules) and the proximal and distal portions of the convoluted tubules make up the major portion of the renal cortex.

The renal medulla contains the remainder of the renal tubules, loops of Henle, and collecting tubules. These tubules form a number of cone-shaped structures called renal pyramids. These pyramids are arranged so their bases are on the outside near the renal cortex. The tips (renal papillae) of the renal pyramids point medially toward the renal pelvis, which is a funnel-shaped basin at the upper end of the ureter.

Urine flows from the collecting tubules through the pyramids and into cup-like extensions of the renal pelvis. These extensions are called calyces.

Nephrons

The major role of the kidneys is to filter water-soluble wastes out of the blood. Nephrons are the functional units of the kidney. They are the cells that form urine; the rest of the urinary system expels urine. More than 1 million microscopic nephrons are in each kidney. Human beings can survive using only one third of their nephrons. The largest portion of each nephron is located in the renal cortex (superficial and midcortical nephrons), except for a small tube located in the medulla. Juxtamedullary nephrons are those near the medulla. At one end of each microscopic nephron is a knotted cluster or tuft of capillaries called the glomerulus.

The glomerulus is partially enclosed in a funnel-shaped structure called Bowman's capsule, which pressure-filters large solutes out of the blood through small pores. The glomerulus and Bowman's capsule together are known as the renal corpuscle.

Because the efferent arteriole (the one leaving the glomerulus) is smaller in diameter than the afferent arteriole, the pressure in the glomerulus is increased. This assists in the pressure filtration of molecules out of plasma.

The walls of the glomeruli have three layers that filter blood. The outside layer of the glomerular membrane is the epithelium. This layer has large openings (pores) that allow all blood components, except RBCs, to pass through until they reach the.

💧 Nephron Anatomy and Function

Glomerular Membrane Layers

The glomerular membrane consists of three layers:

1. Endothelium (inner layer)

2. Basement membrane (middle layer): Prevents the passage of large proteins through filtration. Alterations in the basement membrane due to diseases like glomerulonephritis and diabetic nephropathy can reduce the kidney's filtering ability.

3. Epithelium (outer layer or capsular membrane): A thin, porous membrane made of specialized cells called podocytes.

   • Podocytes: Have extensions called pedicels that branch out on the basement membrane surface.

   • Spaces between pedicels restrict medium-sized proteins from entering the glomerular filtrate.

Blood Flow Through the Glomerulus

1. Afferent arteriole: Blood with filterable wastes and food products enters the glomerulus.

2. Capillary loop: The afferent arteriole divides to form this. Water, wastes, glucose, and salts filter through the thin walls into Bowman's capsule as a dilute solution.

3. Efferent arteriole: Capillaries unite to form this, which carries away the remaining blood.

Convoluted Tubules

1. Proximal Convoluted Tubule (PCT):

   • Selective reabsorption: Glucose, amino acids, and salts are actively transported across membranes and returned to the blood.

   • Brush border: Contains many villi to accomplish selective reabsorption.

   • ATP production: Mitochondria produce ATP to assist in active transport.

2. Loop of Henle (Nephron Loop):

   • Concentrates salts: Reabsorbs water via osmosis.

3. Distal Convoluted Tubule (DCT):

   • Tubular secretion: Site where molecules like creatinine and hydrogen ions are secreted.

Juxtaglomerular Apparatus (JGA)

Specialized glandular cells responsible for maintaining blood pressure. Lies at the point where the distal convoluted tubule contacts the afferent arteriole.

Collecting Tubule/Duct System

• Antidiuretic hormone (ADH): Exerts its effects to control the tubule's permeability to water, regulating urine concentration or dilution.

• Peritubular capillaries: Reabsorb water, salts, and glucose.

• Urine continues through the renal pyramid to the renal pelvis and onward to the ureter and bladder.

🩸 Role of Hormones and Other Substances

Renin-Angiotensin-Aldosterone (RAA) Mechanism

• Renin: Secreted by the juxtaglomerular apparatus (JGA) when blood pressure or circulating blood volume falls too low.

• Angiotensin I formation: Renin stimulates this. Then, in the presence of a converting enzyme, it changes to angiotensin II.

• Angiotensin II: Causes blood vessels to constrict, raising blood pressure, and stimulates the adrenal cortex to secrete aldosterone.

• Aldosterone: Promotes sodium and water retention, increasing blood volume and further elevating blood pressure. Also responds to high blood levels of potassium or low levels of sodium by stimulating the excretion of potassium ions and reabsorption of sodium ions.

Antidiuretic Hormone (ADH)

• Secreted by the posterior pituitary gland in response to angiotensin II and low fluid levels in the body.

• Increases water reabsorption by the kidney tubules, decreasing the amount and increasing the concentration of urine secreted.

• Maintains circulating blood volume, blood pressure, and homeostasis.

• Stimulates the thirst center in the hypothalamus, increasing fluid intake.

Vitamin D

• Synthesized in the skin by reaction with ultraviolet rays in sunlight or obtained from fish liver oil and irradiated milk.

• Plays an important role in absorption of calcium from the gastrointestinal tract, which is necessary for bone and teeth formation.

• Must be converted in the liver and kidneys to become metabolically active. Individuals with renal disease may have calcium imbalances due to the inability to convert inactive vitamin D to the active form.

🔄 Renal Blood Flow

• Renal arteries: Branch from the aorta close to the heart, providing a generous and highly oxygenated blood supply to the kidneys.

• Afferent arterioles: Smaller arteries that supply blood to the glomeruli.

• Glomeruli: Have higher blood pressure than most body capillaries (60 mm Hg versus 30 mm Hg), necessary to form glomerular filtrate.

• Efferent arterioles: Arise from the glomeruli and carry blood away.

• Peritubular capillaries: Branch off from the efferent arterioles and surround the convoluted tubules.

• Veins: Peritubular capillaries drain into these (interlobular, arcuate, and interlobar veins), ending at the renal vein.

• Renal vein: Empties into the inferior vena cava for return of blood to the heart.

Sites of Capillary Exchange

• Glomeruli: Begin the formation of urine.

• Peritubular capillaries: Carry substances from the kidneys back to the circulatory system for reuse and nourish the renal tissue.

🫙 Organs of Urine Storage and Elimination

• Ureters: Narrow tubes (0.5 cm in diameter and 25-30 cm long) lined with mucous membrane, which attach to the kidneys at the renal pelvis and carry urine to the urinary bladder. Smooth muscles contract in peristaltic waves to carry urine.

• Urinary bladder (vesica): A hollow muscular sac that stores urine, located behind the symphysis pubis. Composed of transitional epithelium and lined with mucous membrane.

• Trigone (vesical trigone): A triangular area on the floor of the bladder that does not expand, with attachments of the two ureters and the urethra.

• Bladder capacity: Varies among individuals; most experience the desire to void at 200-400 mL, with a maximum capacity of about 1,000 mL.

• Sphincters:

  • Involuntary internal sphincter: Relaxes as it senses the body's voluntary impulse to void.

  • External sphincter: Under conscious control.

• Urination (voiding): Initiated by contraction of the detrusor muscle and relaxation of the external sphincter.

Urethra

• Bladder wall openings: Two from the ureters and one into the urethra.

• Male urethra: About 8 inches (20 cm) long, passing through the prostate gland and the penis, serving as a passageway for both urine and sperm.

• Female urethra: Short, about 1.5 inches (3.8 cm) long, opening to the outside at the urinary meatus.

🌡 Blood Pressure Regulation

• Decreased systemic blood pressure causes reduced stretching of receptor cells in the juxtaglomerular apparatus and a decrease of water volume in the kidneys. This causes the JGA to secrete renin, which in turn initiates the renin-angiotensin-aldosterone mechanism.

• Renin-angiotensin-aldosterone mechanism: Returns blood pressure to a safe range by causing vasoconstriction of peripheral arterioles, increasing glomerular filtration rate, and preventing water and salt excretion, increasing blood volume.

• Decreased renal blood flow results in reduced urinary output.

💧 Urine Formation

• Normally, about 1,000-1,500 mL of urine is formed daily. Urine formation in the nephron occurs through three major processes: glomerular filtration, tubular reabsorption, and tubular secretion. A fourth process allows additional water to be reabsorbed via hormonal control, specifically ADH.

Glomerular Filtration

The process of removing particles from a solution by allowing the liquid solvent to pass across a barrier.

• Blood enters the glomerulus, increasing pressure, and forces glomerular filtrate out of the glomerulus into Bowman's capsule.

• Glomerular filtrate: Similar to plasma but contains no blood cells and almost no protein.

• Contains water, glucose, urea, creatinine, and numerous salts (electrolytes).

• Glomerular Filtration Rate (GFR): The amount of filtrate formed in all glomeruli of both kidneys per minute. Normal GFR in an adult is about 125 mL/min (about 180 L/day).

• Specific forces promote filtration of waste products into the kidneys, and other forces resist filtration.

• Net filtration pressure: The difference between forces enabling and resisting filtration.

Tubular Reabsorption

• As filtrate passes through the convoluted tubules, 99% is reabsorbed back into circulation via the efferent arteriole and peri-tubular capillaries.

• Useful substances, such as water, salts, and organic molecules, enter the interstitial fluid and eventually renal veins.

• Active and passive transport mechanisms cause reabsorption.

• The proximal tubules reabsorb most (approximately 65%-80%) of the electrolytes that the body retains.

• Sodium ions (Na): Are carried by active transport.

• Pinocytosis: Responsible for reabsorption of most small proteins and peptides.

Renal Threshold

The upper limit for how much of a substance the tubules can reabsorb into the general circulation.

• When tubules reach their threshold, they excrete the excess amount of each substance into urine.

• Transport maximum (TM): The upper limit of a given substance reabsorbed within a given time period.

Tubular Secretion

The process by which substances move from blood into the urine.

• Occurs by active or passive transport before filtrates leave the body as urine.

• Molecules secreted in peri-tubular capillaries move into tubular cells, then into the tubular lumen.

• Secretions into urine include end products of metabolism, such as ammonia, bile pigments, and urea, along with metabolites of drugs.

• Ions, such as hydrogen (H) and potassium (K), are also subject to tubular secretion.

⚖ Water Reabsorption Under The Influence of ADH

• About 10% of water is reabsorbed under the influence of antidiuretic hormone (ADH).

• When secreted, ADH allows water to be reabsorbed from the distal convoluted tubule and collecting duct (back into the blood).

• The lower the concentration of water in the blood, the more concentrated the blood is (elevated osmotic pressure). When there is high osmotic pressure because of concentrated blood, more ADH is secreted, allowing additional water reabsorption back into the blood.

• Helps maintain the body's homeostasis.

🧪 Characteristics and Composition of Urine

• The body excretes about 1,000-1,500 mL (2-3 pints) of urine daily.

Factors Influencing Urine Quantity

• Amount of fluid and salt intake

• Perspiration

• Hemorrhage

• Blood pressure

• Vomiting

• External temperature

• Drugs

• Fever

• Various diseases

Characteristics of Urine

• Clear yellow liquid with a characteristic odor.

• Color: Can vary; amber or dark yellow may indicate dehydration.

• pH: Normally acidic, but can vary depending on diet.

• Turbidity: May become cloudy if left sitting.

• Odor: Ammonia-like smell if left sitting.

Specific Gravity

The relationship between urine and pure water.

• Specific gravity of pure water is 1.000.

• Normal urine specific gravity is about 1.010-1.025.

• Higher specific gravity indicates more concentrated urine and could be secondary to dehydration or urinary retention.

• Low specific gravity indicates dilute urine and may be secondary to overhydration or a physical disorder.

Composition of Normal Urine

• 95% water (solvent)

• 5% solutes

  • Nitrogenous waste products (urea, uric acid, and creatinine)

  • Excess minerals from the diet (sodium, potassium, chloride, calcium, sulfur, and phosphate)

  • Toxins and certain drug metabolites

  • Hormones (especially sex hormones)

  • Pigments caused by certain foods or drugs

Abnormal Products in Urine

• Blood

• Glucose

• Pus

• Large amounts of bacteria

• Casts

• Ketone bodies

• Bile

• Albumin (protein)

Micturition

The release of urine from the body, also called voiding or urination.

• Involuntary micturition is called urinary incontinence.

• Urine flows from the collecting tubules into the renal pelvis, down the ureters, and into the bladder.

• As urine distends the bladder, it stimulates nerve endings in the bladder walls. The brain interprets the message of fullness and stimulates the sphincter muscles to relax.

• The external sphincter is controlled voluntarily.

👴 Aging and the Kidneys

• The ability of kidneys to filter blood, reabsorb electrolytes, and secrete wastes decreases with age.

• Kidneys have less ability to return to normal after abrupt changes in blood volume, electrolytes, and acid-base balance.

• The number and size of nephrons normally decrease after approximately age 40, with an approximate 30%-50% loss of functioning nephrons occurring by age 80.

• This functional loss decreases the GFR, resulting in a decreased clearance of protein waste products.

• Drugs may reach toxic levels because they are not adequately filtered and removed.

• Secretion and removal of substances, such as ammonia, are not as efficient.

• The threshold for glucose decreases, and higher blood sugar levels may be noted.

• The bladder often has a smaller capacity, leading to urinary frequency and nocturia.

• Bladder muscles often become weaker, leading to urinary retention, dribbling, and stress incontinence.

👨‍ Male Reproductive System: Structure and Function

• The male reproductive system functions to produce and transport sperm. A man's reproductive capacity is directly associated with sexual excitement, penile erection, and ejaculation.

• Consists of the testes (produce sperm), ductal system and seminal vesicles (store and transport sperm), scrotum (holds testes and regulates their temperature), penis (required for sperm deposit in female), and accessory glands (produce male hormones and other secretions).

Testes

Also known as testicles, reproductory organs, or sex organs, they produce spermatozoa (sperm cells) through a process called spermatogenesis and secrete sex hormones.

• Two almond-shaped glands, one on each side of the scrotum.

• Small, approximately 1.5-2 inches (3.7-5 cm) long and 1 inch (2.5 cm) wide and thick.

• Usually one testis hangs lower than the other, probably to keep them from hitting each other.

• Suspended from the ductus deferens, the beginning portion of the spermatic cord.

• Covered by tissue layers, one of which partitions the testis into 250-300 wedge-shaped lobules.

• Each lobule contains the functional units of the testis, the seminiferous tubules.

• Combined length of seminiferous tubules is about half a mile.

• Between the tubules are small clusters of specialized endocrine cells, called interstitial cells, which secrete testosterone and other androgens (male hormones).

• The cells lining the tubules produce sperm.

Ductal System

• Stores and transports sperm from the testicles to the urethra.

• Includes the paired epididymides, the ductus deferentia, and the ejaculatory ducts.

Epididymis

A long, comma-shaped organ attached to the posterior surface of the testis, storing sperm cells.

• A tightly coiled tube approximately 20 feet (6 m) long.

• Millions of sperm cells are in their final stages of maturation, developing a tail and gaining motility.

• Sperm cells are unable to fertilize an egg unless they mature in the epididymis.

• Smooth muscles propel sperm into the ductus deferens.

Ductus Deferens (Vas Deferens)

These tubes transport sperm from the epididymis to the ejaculatory duct.

• About 11.5-18 inches (30-45 cm) long.

• Each ductus deferens passes upward posterior to the testis, then into the abdominal cavity, and continues over the top and down the posterior surface of the urinary bladder, into the pelvic cavity.

• Peristaltic contractions propel sperm cells through the ductus.

• Each ductus deferens joins a duct from the seminal vesicles.

• These ducts, together with blood vessels, lymphatic vessels, nerves, and connective tissue coverings, make up the spermatic cord.

• The spermatic cord passes through an opening in the muscular abdominal wall called the inguinal canal.

Ejaculatory Ducts

• About 1 inch (2 cm) long.

• Each one originates where the ampulla of the ductus deferens joins the duct from the seminal vesicle.

• The ejaculatory ducts empty into the urethra.

• The ejaculatory ducts also receive secretions from the prostate gland, to make up semen.

Scrotum

A sac-like structure that encloses the two testes, suspended behind the base of the penis.

• Supports and protects the testes.

• Regulates the temperature of the testes.

• The cremasteric muscles involuntarily contract and tighten the spermatic cord to bring the testicles closer to the body as external temperature lowers.

• The temperature of the testes (35°C or 95°F) is lower than internal body temperature (37°C or 98.6°F). This temperature is maintained to facilitate sperm production.

Penis

A cylindrical organ located between the upper thighs immediately in front of the scrotum.

• Composed of three masses of cavernous (erectile) tissue, each of which contains smooth muscle, connective tissue, and blood sinuses (large vascular channels).

• The corpus cavernosum is on either side, with the corpus spongiosum in the center.

• At the time of sexual excitement, blood fills the sinuses and the penis becomes firm and raises up, an erection.

• The smooth cap of the penis surrounding the corpus spongiosum is sensitive and is called the glans penis or head of the penis.

• Covered by a fold of loose skin that forms the hood-like foreskin (prepuce).

• Surgical removal of the foreskin is called circumcision.

• The urethra within the penis serves as a common passageway for both the urinary and reproductive systems.

Bulbourethral (Cowper's) Glands

• Located between two layers of fascia just below the prostate glands.

• Approximately the size of a pea, they are composed of several lobules held together by fibers.

• They secrete an alkaline mucus into tiny ducts, which empty into the urethra.

• This mucus coats the urethra to neutralize the pH of urine residue; it also lubricates the penis.

👦 Male Puberty and Hormones

• The male reproductive system develops during childhood and adolescence. It does not become functional until hormones are secreted during puberty (pubescence), the stage of life during which the reproductive organs become fully functional. In boys, puberty usually occurs between 12 and 16 years of age.

• Hormones from the hypothalamus, pituitary gland, and gonads influence the reproductive system.

• When a boy reaches puberty, the hypothalamus stimulates the secretion of both interstitial cell-stimulating hormone (ICSH) and follicle-stimulating hormone (FSH) from the anterior pituitary; both are gonadotropic hormones.

• In the man, these hormones have two main effects:

  • They stimulate the gonads (sex glands) to secrete specific male hormones (androgens).

  • FSH stimulates the formation of sperm.

• The major androgen is testosterone. ICSH stimulates the production of testosterone. During puberty, male glandular development becomes very active and influences the development of secondary sexual characteristics.

🧑‍⚕ Male Sexual Characteristics and Function

Secondary Sexual Characteristics in Males

• Development of typical male beard, pubic, and axillary hair, as well as increased body hair.

• Development of unique musculature, including broader shoulders and narrow hips.

• Voice deepens, and the "Adam's apple" develops (unique to males).

• Testosterone maintains the functioning of male accessory organs and stimulates protein anabolism.

🧬 Sperm Cells and Spermatogenesis

Spermatogenesis: The formation of mature and functional spermatozoa. Begins around age 12-13 and continues throughout life, stimulated by testosterone in the seminiferous tubules of the testes.

• Sperm cell (spermatozoa): The male gamete necessary for initiating the development of a new individual.

• Normal spermatogenesis occurs at temperatures around 35°C (95°F).

• Spermatogonia: Stem cells of sperm cell development.

• Sertoli cells: Facilitate spermatogenesis.

• Spermatogonia divide via mitosis and meiosis to form spermatocytes.

• Spermatocytes form spermatids, which develop into spermatozoa.

• Each primary spermatocyte forms four functional gametes.

• Testes produce millions of spermatozoa daily; maturation takes about 2 months in the ductus deferens.

Sperm Cell Structure

ComponentDescriptionHeadContains 23 chromosomes (half the human genetic material).AcrosomeTip of the head containing enzymes to dissolve the ovum's cell wall.BodyMiddle piece containing mitochondria, providing energy for locomotion.TailFlagellum that propels the sperm with a lashing motion.

Semen Composition

• Semen (ejaculatory fluid): Contains 60-100 million sperm cells per milliliter after combining with sperm in the ejaculatory duct.

  • Sperm counts less than 10-20 million per milliliter may impair fertility.

  • Ejaculated volume varies from 2-5 mL.

  • Sperm can survive up to 3 days in the vagina.

  • Averages of 250 million sperm cells are ejaculated, but only about 100 reach the ovum in the oviduct.

• Other substances in semen: citric acid, fructose, enzymes, coagulation proteins, lipids (fats), prostaglandins, and other secretions from the seminal vesicles and prostate.

• Pre-ejaculate: A clear liquid secreted by the bulbourethral glands during sexual arousal to lubricate the urethra and clear out urine or foreign matter.

🍆 The Male Sex Act

• Copulation/Intercourse/Coitus: Sexual union between a man and a woman, where the man inserts his erect penis into the vagina and deposits semen.

• Complex series of reflexes: erection, secretion, emission, and ejaculation.

  • Erection: Nervous impulses cause vasodilation of the arteries in the penis. Arterial dilation obstructs venous return, engorging the cavernous tissue with blood.

    • Inability to achieve erection is called impotence.

  • Emission: Accumulation of sperm cells and secretions in the urethra.

  • Ejaculation: Forceful expulsion of semen from the ejaculatory ducts through the urethra.

  • Orgasm: Physical, emotional, and pleasurable sensation at the climax of sexual intercourse, accompanied by ejaculation of semen.

    • Difficulty in achieving orgasm is called anorgasmia.

• Oligospermia: Low sperm count.

🚺 Female Reproductive System: Structure and Function

🥚 Overview

• Responsible for the continuation of the human species through internal fertilization via sexual intercourse.

• Female system produces eggs (ova), which can be fertilized by sperm.

• Provides an environment for the growth and development of a fetus.

• Gyn-/Gyneco-: Word element meaning "woman."

• Development of reproductive and urinary systems is closely related.

• Müllerian duct: Fetal structure that develops into various female structures.

• Homologous structures: Structures that are the same in fetal life but differentiate between sexes in adult life.

Homologous Structures Between Males and Females

MaleFemaleFunctionCowper's glandBartholin's glandsSecrete lubricantsPenisClitorisErectile tissue; contributes to sensationTestesOvariesProduce gametesProstate glandSkene's glandProduce ejaculatory fluid and sensation

• Men produce sperm continuously from puberty onwards, while a woman's reproductive capacity is limited, beginning with the first menstrual period and ending at menopause.

🌸 Anatomy of the Female Reproductive System

• Consists of paired ovaries and oviducts, uterus, vagina, and external genital structures.

• Internal organs (uterus, vagina, and ovaries) are located within the pelvis between the urinary bladder and rectum.

  • Held in place by ligaments (broad and round ligaments).

• External structures: components of the vulva.

• Mammary glands (breasts) are considered female reproductive organs.

Ovaries

• Gonads (sex organs) in women.

• Produce female gametes (ova) and secrete female sex hormones (estrogens, primarily estradiol).

• Almond-shaped glands, about 1.5 inches (3.8 cm) long, located within the brim of the pelvis.

  • Oophor/o-: Combining form relating to the ovary.

Oviducts (Fallopian Tubes or Uterine Tubes)

• Passageway for the ovum between the ovary and the uterus, 4-5 inches (10-12.5 cm) long.

• One oviduct connects to each side of the uterus, associated with one ovary.

• Fimbriae: Fringe-like ends of the oviducts that catch the ovum as it bursts from the ovary.

• Cilia on fimbriae and oviduct lining help move the ovum towards the uterus.

• Smooth muscles contract in peristaltic waves to propel the ovum.

• Inner layer contains mucus-secreting cells that assist in transporting the ovum and provide nutrients.

  • Transit time from ovary to uterus can take a few hours or several days.

• Fertilization (meeting of sperm and ovum) normally occurs midway in the oviduct.

  • Zygote: Fertilized ovum that travels to the uterus.

  • Embryo: Zygote embedded in the uterine lining.

• If fertilization doesn't occur, the ovum dissolves.

Uterus (Womb)

• Hollow, muscular, upside-down pear-shaped organ in the center of the pelvic cavity.

• Major female sex organ, despite the ovaries being the gonads.

• Non-pregnant uterus: about 3 inches (7.5 cm) long, 2 inches (5 cm) wide, and 1 inch (2.5 cm) thick.

• Zygote matures into a full-term fetus in the uterus.

• Normally anteverted (tipped forward), but can be retroverted (tipped posteriorly) in some women.

• Held in position by strong ligaments (broad and round).

• During pregnancy, increases in size about 16 times and capacity increases from about 2.5 mL to 5,000 mL.

• After pregnancy, shrinks but never returns to original size.

• Hystero-: Combining form relating to the uterus; removal of the uterus is called hysterectomy.

Uterine Structure

PartDescriptionFundusRound upper surface where the oviducts enter.Body (Corpus)Broad, large central portion.CervixCylindrical or conical narrow lower end that opens into the vagina at the external cervical os (mouth of cervix).

• Non-pregnant cervix feels like the end of your nose.

Uterine Layers

LayerDescriptionSerousOuter layer, called the perimetrium; a fold of the peritoneum.MuscularMiddle layer, called the myometrium; smooth muscle that increases in size during pregnancy and contracts during labor and delivery.MucousInner layer, called the endometrium; forms the maternal portion of the placenta during pregnancy.

• Function: receives the fertilized ovum, provides housing and nourishment for a fetus, and expels the fetus (delivery).

Vagina

• Fibromuscular canal, about 4 inches (10 cm) long, attached to the uterus through the cervix.

• Meets the external organs at the vulva.

• Superior, domed portion has deep recesses called fornices around the cervix.

• Moistenend by glandular secretions from Bartholin's glands and the mucous membrane lining its walls.

  • Mucus is acidic to retard microbial growth.

  • Alkaline semen can temporarily neutralize the vagina's acidic environment.

• Rugae: Expandable folds within the vaginal walls that accommodate insertion of the penis and passage of the fetus during childbirth.

• Functions: receive sperm, provide an exit for menstrual flow, and serve as the birth canal.

• Hymen: Thin membrane over the vaginal opening.

  • May close the vaginal orifice completely, or may be absent from birth.

  • Commonly has perforations.

  • Presence or absence is not a reliable indicator of virginity.

Vulva (Pudendum)

• Collective term for the external genitalia, including the vestibule and its surrounding structures.

• Structures:

  • Vestibule: contains openings of the urethra, vagina, and Bartholin's glands.

  • Mons pubis: fatty pad over the symphysis pubis.

  • Labia majora (labium majus): rounded folds of skin extending posterior to the mons pubis, covered with coarse pubic hair after puberty.

  • Labia minora (labium minus): thin pair of skin folds medial to the labia majora, uniting above the clitoris to form the prepuce of the clitoris or clitoral hood.

  • Clitoris: small erectile structure that responds to sexual stimulation, similar in structure to the penis.

    • Becomes engorged with blood during sexual excitement.

    • Stimulation often leads to orgasm.

  • Prepuce of the clitoris or clitoral hood: thin pair of skin folds that medial to the labia majora that untie above the clitoris.

• Vestibule floor: Contains Bartholin's glands (greater vestibular glands), which lubricate the vagina.

  • Obstruction of these glands can result in Bartholin's cysts.

Perineum

• Female (obstetrical) perineum: Space between the vaginal orifice and the anus.

  • Made up of strong muscles that support pelvic organs.

Breasts (Mammary Glands)

• Not involved in gestation but hormonally influenced and linked to the reproductive process.

• Provide nutrition for babies after childbirth.

• Before puberty, breast structure is similar in boys and girls.

• Estrogens and progesterone in girls lead to breast enlargement at puberty.

• Modified sweat glands located anterior to the pectoralis major muscles.

• Hormones (prolactin and oxytocin) stimulate them to produce and release milk after childbirth.

• Divided into 15-20 lobes of glandular tissue, covered by adipose (fat) tissue.

  • Lobes are made up of lobules, which consist of milk-secreting cells in glandular alveoli.

  • Small lactiferous ducts converge from the alveoli towards each nipple.

  • Each lactiferous duct forms a small reservoir for milk.

Breast Structures

StructureDescriptionNippleCircular projection containing some erectile tissue.AreolaPigmented area surrounding the nipple.Areolar glandsClose to the skin's surface; secretions keep the nipples from drying out, especially during lactation.

• Hormonal release of estrogen and progesterone during pregnancy causes the breasts to enlarge, and the areolae become more heavily pigmented.

🧪 Hormonal Regulation

• Hypothalamus, pituitary gland, and gonads contribute to hormonal regulation.

• Androgens (male hormones) and estrogens (female hormones) are at similar levels in both boys and girls before puberty.

• The hypothalamus stimulates the secretion of gonadotropic hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

  • LH and FSH stimulate the formation of ova and hormone secretion from sex organs.

  • Also stimulate the development of secondary female sexual characteristics.

• The ovaries begin to secrete estrogens (estradiol, estriol, and estrone).

• After puberty, the corpus luteum produces progesterone, which functions primarily during pregnancy.

Secondary Sexual Characteristics in Females

• Smaller stature

• Higher percentage of body fat tissue

• Wider hip structure

• Pubic and axillary hair

• Development of breasts

• Sweat glands become more active

• Voice deepens and matures

• Menstruation occurs

• All female secondary sex characteristics depend on the secretion of estrogens and progesterone.

🥚 Oogenesis

• It is believed that all ova (egg cells) a woman will produce are present as oocytes at her birth.

• Oocytes develop in different stages throughout a woman's life.

• Oogonia: Begin to develop in the female fetus' fourth to fifth gestational month.

  • Most degenerate or begin meiosis (cell division) before birth.

  • Primary oocyte: Oogonium at the start of meiosis.

• A newborn girl has about 2 million primary oocytes.

  • The number decreases to 300,000-400,000 between birth and puberty.

  • Only 300-400 eventually develop into mature egg cells.

• Haploid cell: Oocyte (gamete) contains half the genetic material required to form a new individual (23 chromosomes).

  • Only if fertilized by a male sex cell (spermatozoa) does the gamete develop into an embryo and fetus.

• At puberty, hormones stimulate the primary follicle to continue development into a secondary follicle.

• The secondary follicle enlarges and forms a bump on the ovary.

• Graafian follicle: Mature secondary follicle.

• From puberty until menopause, a mature graafian follicle ruptures the surface of the ovary at approximately monthly intervals.

• Ovum: Expelled into the pelvic cavity near the oviduct, which leads to the uterus.

  • Lives up to 24 hours before degenerating unless fertilized by sperm.

• If fertilization and implantation take place, the ovum becomes an embryo, which develops into a fetus.

• When the fetus is developed enough to survive outside the uterus, the cervix dilates.

• Contractions of the uterus cause the fetus to be expelled through the vagina (childbirth).

🩸 The Menstrual Cycle

• Two interrelated continuous cycles: the ovarian cycle and the uterine cycle.

• Controlled by secretions from the anterior pituitary gland.

• Changes occur in sexually mature, non-pregnant women, culminating in menstruation.

• Menstruation: The flow of blood and other materials from the uterus through the vagina.

• Menarche: The first menstrual period, marking the onset of puberty.

• This rhythmical series of changes occurs about every 28 days.

  • Referred to as a menstrual period, menses, or period.

  • Great variation occurs among women and within one woman's month-to-month cycle.

• Menstrual cycles continue as long as ovarian hormones stimulate the uterine lining.

• Between approximately 40 and 55 years of age, the ovaries become less active because they no longer respond to FSH.

  • Eggs no longer mature, and the ovaries stop producing estrogens.

  • Results in the lack of ability to become pregnant and the onset of menopause (cessation of menstruation).

• Menopause: A normal process that sometimes occurs abruptly but is usually gradual.

  • May experience symptoms such as headaches, irritability, insomnia, anxiety, or depression.

  • One of the most common symptoms is the sensation of heat (hot flashes).

  • External indicators: weight gain, thinning of hair, growth of hair on the upper lip and chin, and dry, itchy skin.

Ovarian Cycle

• The ovum matures and is expelled from the ovary into the oviduct.

• Maturation of another ovum is withheld until the next cycle.

• Three phases: follicular phase, ovulation, and luteal phase.

Phases of the Ovarian Cycle

PhaseDescriptionFollicular PhaseLasts from about day 4 to about day 14. Under the influence of FSH, several follicles begin to ripen, and the ovum within each begins to mature. One follicle will become dominant; it is called the graafian follicle. The other follicles stop growing.OvulationAt about day 14, a surge of hormones causes the ovum to burst through the ovary. Usually occurs in the middle of the 28-day menstrual cycle (about 14 days before the onset of the next menses).Luteal PhaseThe empty, ruptured graafian follicle becomes the corpus luteum and begins to secrete progesterone and estrogen, which cause the endometrium (the endometrial lining of the uterus) to become greatly thickened and vascular (engorged).

• If the ovum is fertilized, it becomes embedded in the endometrium and becomes a fetus.

• If the ovum is not fertilized, the secretion of progesterone decreases, and the corpus luteum begins to decline (and menstruation occurs).

• Levels of FSH start to rise on about day 2 of the cycle to begin preparation for the next cycle.

Uterine Cycle (Endometrial Cycle)

• This process prepares the uterus for implantation of an ovum (egg).

• Controlled by the ovarian cycle and varies depending on whether or not fertilization occurs.

• Three phases: the proliferative phase, the secretory phase, and the menstrual (menstruation) phase.

Phases of the Uterine Cycle

PhaseDescriptionProliferative PhaseWhile the ovarian follicles are producing increased amounts of estrogen, the endometrium prepares for possible fertilization with pronounced growth. It thickens from about day 4 to about day 14.Secretory PhaseIf fertilization does not occur, the corpus luteum degenerates and hormonal levels fall. Withdrawal of hormones causes the endometrial cells to change, and menstruation begins.MenstruationThe sloughing off of the endometrium and unfertilized ovum causes menstruation, which averages 3-5 days but may last 2-8 days. During menstruation, FSH levels rise and several ovarian follicles begin to develop again, beginning the next endometrial cycle.

👩‍⚕ Female Sexual Response

• Female neural pathways involved in controlling the sexual response are the same as those in the male.

• During sexual excitement, the erectile tissues within the clitoris and around the vaginal opening become engorged with blood.

• The vestibular glands secrete mucus before and during coitus (sexual intercourse).

• If the clitoris is stimulated with sufficient intensity and duration, the woman will feel the physical and psychological release of orgasm.

• The nipples of the breasts also contain erectile tissues that respond to sexual excitement and orgasm.

• Unlike a man, a woman can experience successive orgasms with minimal rest.

👵 Female Climacteric

• Also called menopause.

• Several physical conditions are associated with loss of estrogen.

• Vascular disease and heart disease are less common in premenopausal women than in men. After menopause, the rate of heart disease between men and women is about equal.

• Osteoporosis: Condition in which bones become brittle and porous and fracture more easily. More common in women and worsens when hormones are absent.

  • Estrogen replacement therapy (ERT) or hormone replacement therapy (HRT) may be prescribed to lessen menopausal symptoms.

• Older women may suffer from urinary incontinence, the result of aging and childbirth trauma.

• Breast tissue may become smaller and more pendulous (sagging) as muscles relax and are replaced by fat.

• Loss of muscle tone causes external genital structures to sag; the vagina shortens and becomes less elastic.

• Intercourse may become painful (dyspareunia) as the vaginal mucosal wall becomes thinner and vaginal secretions decrease.

• The uterus may fall (prolapse) into the vagina.

• Older women are more susceptible to vaginal infections.

• Changes in sexual response are relatively minor and usually related to physical changes in the vagina.

🩺 Vital Signs: The Body's Indicators

Vital signs (VS), also known as cardinal symptoms, include:

• Body temperature (T)

• Pulse (P)

• Respiration (R)

• Blood pressure (BP)

These measurements indicate functions necessary to sustain life. Healthcare facilities observe these signs regularly (morning and evening) for all patients. Frequent observation is necessary for some illnesses to detect variations indicating a change in the patient's condition.

📝 The Graphic Record: Documenting Vital Signs

The graphic record is used to document large amounts of information for all members of the healthcare team, including:

• Vital signs

• Fluid intake and output (I&O)

• Weight

• Bowel movements

The graphic record is assessed at regular intervals. It can be a paper document in the patient's chart or an electronic record. It provides a picture of the variations that occur throughout the patient's illness. Vital signs must be recorded accurately and promptly to provide continuous and current documentation, helping providers diagnose and respond to the patient's changing condition. Steps for recording vital signs include:

• Locate the current date on the graphic record.

• Record temperature by making a dot on the scale parallel to the temperature value under the designated time.

• Record pulse rate by making a dot on the scale parallel to the pulse rate under the designated time.

• Record respiratory rate at the bottom of the graph with numbers.

• Record BP with written numbers or by making a dot on the scale parallel to the BP value under the designated time.

• Record other information, such as weight, bowel movements, and the totals for I&O, with written numbers in the spaces provided.

In critical care areas, after surgery, or in the immediate postpartum period, vital signs may be taken every 5, 10, or 15 minutes and graphed on a frequent vital signs sheet. Space is often available to record other information, such as intravenous (IV) fluids, I&O, weight, medications, and notes.

🔥 Assessing Body Temperature

Body temperature is the measure of heat inside a person's body (core temperature), a balance between heat produced and heat lost. Heat is generated from burning food and is lost through the skin and lungs.

Normal body temperature using oral measurement is ~37°C or 98.6°F; however, variations can still be considered "normal" for an individual.

Signs of Temperature Imbalance

• Elevated temperature: flushed face, hot skin, unusually bright eyes, restlessness, chills, and thirst.

• Subnormal temperature: a lifeless manner and pale, cold, clammy skin.

The hypothalamus regulates body temperature by controlling blood temperature. Heat is a product of metabolism. Muscle and gland activities generate most body heat. For example, exercising, active adrenal glands, and digestion increase body temperature. Cold, shock, and certain drugs depress the nervous system and decrease heat production.

Normal Body Temperature Range

A degree difference (Fahrenheit) is considered to be within normal limits in the absence of fever or hypothermia symptoms. Normal temperature is unique for each individual, and most patients can tell when they have a fever or do not feel well. Body temperature is often lowest in the morning and highest in the late afternoon and evening. Normal temperatures for newborns are higher than for adults. The body temperature gradually lowers to the adult normal temperature as the child matures. Other influences on normal body temperature include ovulation, childbirth, and individual metabolism.

Temperature∘C=(Temperature∘F−32)×59Temperature∘C=(Temperature∘F−32)×95​Temperature∘F=(Temperature∘C×95)+32Temperature∘F=(Temperature∘C×59​)+32

ROUTETEMPERATURE RANGESTIMEOral (mouth)35.5°C-37.5°C (95.9°F-99.5°F)0.5-1.5 minRectal (anus)36.6°C-38°C (97.9°F-100.4°F)0.5-1.5 minAxillary (armpit)34.7°C-37.3°C (94.5°F-99.1°F)1-3 minTympanic35.8°C-38°C (96.4°F-100.4°F)1-2 secTemporal artery (TA)35.8°C-38°C (96.4°F-100.4°F)1-2 sec

🔥 Elevated Body Temperature

Temperature rises when the body's heat production increases or heat loss decreases; both may occur simultaneously. A person with a fever (pyrexia) is said to be febrile. Fever often accompanies illness and signifies an infection, and can be useful in fighting pathogen infection. Oral temperatures can range from 37.5-39.4°C (100-103°F) or greater. Very high temperatures can be life-threatening.

• Intermittent fever: A temperature that alternates between a fever and a normal/subnormal reading.

• Remittent fever: A temperature that rises several degrees above normal and returns to normal/near-normal.

• Constant fever: A fever that stays elevated.

• Crisis: A sudden drop from fever to normal temperature.

• Lysis: When an elevated temperature gradually returns to normal.

• Relapsing fever: Fever that returns to normal for at least a day and then occurs again.

🧊 Lowered Body Temperature

Hypothermia is when the temperature is significantly below normal. Hypothermia may precede death or result from overexposure to the elements or cold water. Sometimes it is beneficial for body temperature to be slightly below normal; slower metabolism decreases required oxygen. Clinical hypothermia is used to perform some surgical procedures. Accidental hypothermia is life threatening and requires immediate treatment.

Equipment for Measuring Body Temperature

Healthcare facilities use electronic or automatic thermometers, which are fast, accurate, easy, and safe to use. Disposable single-use thermometers made of paper are available for one-time use and are often used in isolation units. Disposable electronic thermometers are also available.

Locations to measure body temperature:

• Oral (O): mouth

• Rectal (R): anus

• Axillary (Ax): armpit

• Tympanic, aural, or otic (TM): ear canal

• Temporal artery (TA): forehead

Best Practices for Measuring Temperature

1. Every healthcare agency has an established routine for measuring the patient's temperature. Follow guidelines accordingly.

2. Wash your hands between patients.

3. Place the bulb or probe so that body tissues completely surround it, except for temporal artery.

4. When using the tympanic probe, surround it with the skin of the outer ear, rather than the mucous membrane, to minimize the risk of spreading infection.

5. Pre-lubricated covers are available for rectal thermometers.

6. Record the temperature on the patient's graphic record. The electronic thermometer provides a digital readout to one-tenth of a degree.

Oral Temperature

Oral temperature measures temperature within the lingual arteries under the tongue (sublingual). It's frequently used for its ease of use and comfort for the patient. It's more accurate than axillary, less accurate than rectal.

• Wait 15 minutes before taking a measurement if the patient has consumed a hot/cold liquid or smoked.

• Do not use the oral method for patients who have an active seizure disorder or are not responsible for their actions (unconscious, confused, uncooperative).

• Do not use with infants or young children; they may accidentally bite the thermometer.

• Do not use in actively suicidal patients; those with injury to the nose or mouth or oral surgery; those with conditions requiring breathing through the mouth; or those receiving oxygen.

Rectal Temperature

Rectal temperature is highly accurate because the probe is placed in an enclosed cavity. Oral temperature can be checked against a rectal temperature. May be used for patients who are unconscious or after mouth surgery. However, tympanic or temporal artery measurements are used more often. The rectal temperature is contraindicated after rectal surgery (and often after vaginal surgery) and in conditions such as diarrhea, colitis, or cancer of the rectum.

Axillary Temperature

The axillary temperature is the least accurate measurement because the skin surfaces in the axillary space may not come together to form a tightly closed cavity around the probe tip. Hold the device tightly in place in the patient's armpit when using this method. It's used frequently for taking the temperature of newborns and for other patients when conditions make the use of any other method impossible or undesirable.

Tympanic Temperature

The tympanic thermometer is placed snugly into the patient's outer ear canal and measures the thermal radiation given off by the tympanic membrane (TM; eardrum) and the ear canal. It's an ideal site for measuring core body temperature, as the temperature of the TM's blood supply is similar to that of the blood surrounding the thalamus. Many pediatric and intensive care units use this type of thermometer because it records a temperature in 1-2 seconds.

Temporal Artery Temperature

The temporal artery (TA) temperature scanner is moved across the forehead and calculates core body temperature or peak body temperature by measuring blood temperature of the TA via infrared technology. It's the quickest (almost instant) and most noninvasive method available. It can be used in many situations: a sleeping child, an unconscious person, a person with a hearing aid or an ear infection, special needs patient, or those who are assaultive or tactile defensive (unwilling to be touched). It's more accurate than the tympanic method and at least as accurate as the rectal method.

🌡 Use of the Glass Thermometer

The sale and distribution of thermometers containing mercury has been illegal in the United States as of January 1, 2006. Nurses should take the opportunity for patient education and encourage proper disposal of mercury-containing items. Glass thermometers containing alcohol are marked with a scale showing whole numbers from 93-196°F, scaled in increments of two tenths. May be for oral use (with a slender-tipped end) or rectal use (with a bulb-shaped end).

❤ Assessing Pulse

Each heartbeat produces a wave of blood that causes pulsations through the arteries. It can be felt through the nerves in the fingertips if the fingers are placed over one of the large superficial arteries that run across bone with little surrounding soft tissue.

Common Pulse Points

• Temporal artery: just in front of the ear

• Mandibular artery: on the lower jawbone

• Carotid artery: on either side of the neck in front

• Femoral artery: in the groin

• Radial artery: in the wrist at the base of the thumb

Pulses counted in these areas may be stated as temporal pulse, mandibular pulse, carotid pulse, or femoral pulse. If none of these are stated, it is assumed that the pulse was a radial pulse.

Pulse Rate

Pulse rate is how often a person's heart beats per minute (heart rate, HR). It varies with the patient's age, size, and weight; normal adult pulse rate is 60-80 beats per minute (BPM). Women have a slightly higher average rate than men. Newborns range from 120-140 BPM; rates for children fall between adults and newborns, according to size and age. Activity affects pulse rate: pulse rate decreases during sleep and increases after vigorous activity or during disease. Strong emotions, some drugs, fever, or an overactive thyroid gland increase pulse rate. Pulse rate increases ~10 beats for every 1°F (0.56°C) increase in body temperature.

Tachycardia: Pulse rate consistently above normal (100 BPM). An abnormally rapid rate that persists may signify heart disease, heart failure, hemorrhage, or some other serious disturbance.

Bradycardia: Pulse rate continuously slow (55-60 BPM). Well-conditioned athletes often have a low pulse rate but otherwise often suggests an abnormality. May occur during convalescence from a long feverish illness. Can be a sign of cerebral hemorrhage, indicating increased pressure on the brain. May also be a sign of complete heart block (non-functioning of the heart's electrical conduction system). Certain medications also lower pulse rate.

Pulse Volume

Pulse volume varies with the blood volume in the arteries, strength of the heart contractions, and elasticity of blood vessels. A normal pulse can be felt with moderate finger pressure when every beat is full and strong; stronger finger pressure obliterates the beats. Full/bounding: pulse is strong and difficult to obliterate. In hemorrhage (considerable loss of blood), every pulse beat may be weak or thready and the pulse is easy to obliterate and difficult to feel.

Pulse Rhythm

In normal/regular rhythm, the spacing of beats is the same.

• Intermittent/irregular pulse: occasionally skips a beat. Pulse can be irregular in force, such that some beats are weak and may not be felt in the radial pulse. Dangerous as this means the heart is actually beating twice as fast as the radial pulse rate indicates. Can be detected by measurement of the apical-radial pulse.

• Pulse irregular in force and rhythm (dysrhythmia) is a sign of some forms of heart disease or an overactive thyroid gland.

Methods & Equipment

Palpation

Palpation: Feeling with the fingers; used to assess radial, temporal, mandibular, carotid, and femoral pulses.

To locate the area of strongest pulsation, palpate the patient's pulse with the first, second, and third fingers of one hand. Count the initial pulsation as zero, and express as BPM. Do not use the thumb, which has its own pulse.

Auscultation

Auscultation: Listening to sounds and counting the apical pulse, normally heard at the heart's apex, will often give the most accurate assessment of pulse rate.

A stethoscope amplifies sounds received in the head of the instrument as they pass through the earpieces. Most stethoscopes have two heads:

• Flat diaphragm: Pressed against the skin to test high-frequency sounds: breath, normal heart, and bowel sounds.

• Cup-shaped bell: Pressed lightly on the skin to collect low-frequency sounds, such as abnormal heart sounds.

The diaphragm of the stethoscope is placed over the heart's apex to assess apical pulse. The apex of the heart is the point of maximal impulse (PMI) and is the location where the apical pulse is best heard. Each heartbeat consists of two sounds, forming a "lub-dub":

• S1S1​, the first sound, is caused by closure of the mitral and bicuspid valves, which separate the atria from the ventricles.

• S2S2​, the second sound, is caused by the closure of the pulmonic and aortic valves.

Doppler

An ultrasonic vascular Doppler device is sometimes used to detect peripheral pulses. Apply a conductive gel and place the Doppler transmitter over the artery being assessed. The earpieces or a special speaker attached to the Doppler device amplify the sounds. They may also be recorded on a computer or on a special printout. Many automated blood pressure machines also measure the pulse. If this is not the case, the nurse counts the patient's pulse (heart rate).

Pulse Measurement Sites

Radial Pulse

The radial artery in the wrist is most commonly used to count the pulse because of its convenient location.

Apical Pulse

The apical pulse (AP) is more accurate than the radial pulse and is always the pulse taken for children younger than 2 years. Always measure the patient's apical pulse if any question arises about the heart's rhythm or rate or if it appears that the heart has stopped. In some cases, the healthcare provider orders apical pulse measurement as a routine order.

Apical-Radial Pulse

An apical-radial pulse (A-R) measurement is ordered when it is suspected that the patient's heart is not effectively pumping blood. If the apical and radial measurements are not the same, a pulse deficit exists. This must be reported to the healthcare provider. Two nurses are needed to carry out this procedure.

Pedal Pulse

Pedal pulse (foot pulse) is felt over the dorsalis pedis artery or the posterior tibial artery of the foot located on top of the foot, posterior to the toes. It can determine blood circulation to the foot from these points. A strong pulse indicates unrestricted circulation to the lower extremities; a weak and irregular pulse suggests impaired/restricted blood flow. Inspect the feet for color, temperature, and presence of edema (swelling). Also observe the condition of the patient's toenails and cuticles. Always check pedal pulse bilaterally (in both feet) for comparison. If a pedal pulse cannot be detected, the documentation should state "pedal pulses not palpable" and indicate if this is in the right or left foot, or both. Avoid documenting "absent pedal pulses" because the pulses may actually be present but are not detectable manually; this is an instance in which the Doppler might be used.

Popliteal Pulse

The popliteal pulse is located posterior to the knee and palpated by placing the fingers in the space behind the knee. It is used to assess circulation to the lower leg or as an alternative means of assessing blood pressure with a large leg cuff.

Carotid Pulse

The carotid pulse, on either side of the neck, can be located directly over the carotid artery. Palpate along the medial edge of the sternocleidomastoid muscle above the cricoid notch. It is easily accessible for checking peripheral pulse and used during self-checks, in shock cases when other pulses are not palpable, and to assess need for cardiopulmonary resuscitation (CPR). The pulse is counted on either side of the neck. The patient's head is positioned midline to the body. Such positioning provides easier access to the pulse, which is obliterated when the head is turned to one side or the other.

🫁 Assessing Respiration

Oxygen keeps body cells alive; accumulated carbon dioxide kills cells. Respiration is the process that brings oxygen into the body and removes carbon dioxide. This exchange takes place in the lungs. Observing respiration closely is necessary to detect signs of interference with the breathing process.

Respiratory Control

Control and regulation by the brain of respiration is stimulated by the proportion of carbon dioxide in the blood. Injury to the respiratory center or to the nerves connecting it with the lungs affects respiration; too little or too much carbon dioxide in the blood also affects breathing. Conditions/injuries causing pain on breathing or obstruction of the airway can affect respiratory function. Examples include injuries to the lungs, the chest muscles, and the diaphragm. Respiration is automatic; people breathe without thinking about it. You can control your breathing to some extent by taking deeper or shallower breaths or even by holding your breath for a limited time. When the limit is reached, automatic control takes over, and your chest muscles relax despite your efforts. A breathing disorder exists if automatic resumption of breathing does not occur.

Apnea: Cessation of breathing

Apnea occurs in sudden infant death syndrome (SIDS), sleep apnea, and other conditions.

Rate and Depth

Normal adult respiration rate is 12-18 breaths per minute. Women have a more rapid rate than men. For newborns, the average rate is ~40 breaths per minute; for children, the average rate varies from 25-35 breaths per minute.

• Eupnea: Normal breathing

• Tachypnea: Respirations abnormally rapid (20-24 breaths per minute)

• Bradypnea: Respirations are abnormally slow and fall below 10 breaths per minute.

AGEAVERAGE RANGE OF RESPIRATION (per minute)Newborn30-80Early childhood20-40Late childhood15-25Adulthood (Men)12-18Adulthood (Women)16-20

TYPEDESCRIPTIONCLINICAL INDICATIONNormal12-20/min and regular rhythmNormal breathing patternHyperpneaIncreased rate and depthResponse to low oxygen levels, anxiety, or exerciseHypoventilationDecreased rate, decreased depth, irregular rhythmCan occur with medication-induced depression of the respiratory center, obesity, chest wall restriction, or airway obstructionCheyne-StokesPattern of alternating periods of deep breathing followed by periods of apnea; regularUsually occurs with severe heart failure, renal failure, drug overdose, increased intracranial pressure; impending deathBiot'sIrregular pattern of rate and depth with intermittent periods of apneaMeningitis, brain damageKussmaul'sIncreased rate, regular pattern, but abnormally deepUsually occurs with extreme exertion, diabetic ketoacidosis, renal failureApneaAbsence of breathingCan occur with choking, sleep apnea, severe asthma, severe infection, heart failure, drug overdose, or neurologic disorders; can lead to brain damage and death

Increases in respiratory rate can be due to excitement, exercise, pain, fever, lung diseases (pneumonia, emphysema), heart disease, hemorrhage, nephritis, and some drugs. Rapid respiration indicates that the body is making an increased effort to maintain the correct balance of oxygen: carbon dioxide. Sighing/yawning is performed by all people occasionally to cleanse the lungs, physiologically expand the small airways and alveoli that are not used during ordinary respiration, and equalize pressure between the outside atmosphere and the middle ear, via the eustachian or auditory tube. Pressure on the brain's respiratory center and cerebral hemorrhage also has this effect. Some drugs depress the respiratory center (e.g., opiates).

Kussmaul's respirations: Accumulation of poisons in uremia and diabetic coma increase the depth of respirations, characterized by labored breathing. Diabetic acidosis and ketoacidosis increase the total acid in the body, in which the body compensates by trying to remove the excess acid through deeper and faster respirations.

Respiration Sounds

• Snoring: Air passageway is partially blocked, common during sleep when the person's tongue falls back due to relaxation, particularly if they sleep on their back.

• Stertorous breathing: Air passes through secretions present in the air passages; bubbling noises/rattles are characteristic before death, when air passages fill with mucus. Sometimes very loud snoring is referred to as stertorous breathing.

• Obstruction near the glottis causes a hissing, crowing sound.

Dyspnea: Difficult or painful breathing; distinct effort to obtain oxygen and get rid of carbon dioxide. Can be temporary (e.g., physical activity, particularly with obesity) or constant (e.g, acute stages of pneumonia/emphysema, heart disease).

Orthopnea: Difficulty is so marked that the patient can only breathe when in an upright position.

Obstructions of the air passages by secretions or foreign objects interfere with breathing. Asthma: difficulty breathing due to bronchi spasms and edema. Normally, the proportion of respirations to heartbeats is 1:5 in adults. Respirations usually increase if pulse rate increases. Usually, pulse rate increases faster than respiration rate. However, respiration rate increases faster than pulse rate in respiratory diseases. Characteristic signs of breathing difficulty are heaving of the chest and abdomen, a distressed expression, and cyanosis (bluish tinge) in the skin, especially in the lips (circumoral cyanosis) and mucous membranes of the mouth. Cyanosis is due to an excess of carbon dioxide. Can spread to nails, extremities, and patient's entire body in severe conditions.

Cheyne-Stokes respirations: Slow and shallow at first, gradually growing faster and deeper, then tapering off until they stop entirely. Periods of apnea may last for several seconds, and then the cycle is repeated. Usually, the patient experiencing Cheyne-Stokes respirations is not cyanotic.

Cheyne-Stokes respirations are serious and usually precede death in cerebral hemorrhage, uremia, or heart disease. Respirations are the easiest vital signs to determine. Each time such determinations are made, check them against the baseline information.

🩸 Assessing Blood Pressure

Assessing blood pressure (BP) is especially important for patients with abnormally high or low readings, for postoperative patients, and for patients who have sustained serious injury or shock. The BP reading gives significant information about the patient's status and is one of the most important parts of nursing assessment. In routine patient care, BP is usually assessed at least twice daily.

Blood pressure is determined by two major factors:

• Cardiac output: Combination of the heart rate and the amount of blood pumped out of the heart with each contraction (stroke volume).

• Peripheral resistance: Resistance of blood vessels to the flow of blood.

Increased peripheral resistance requires the heart to pump harder to push blood through the blood vessels. This includes loss of elasticity in the walls of the vessels (arteriosclerosis, "hardening of the arteries"), a buildup of plaque (atherosclerosis), or a combination of the two. Peripheral resistance decreases when the walls of the blood vessels become distended (stretched), and blood pressure lowers. A certain amount of elasticity is required for blood to circulate. The volume of blood circulating influences blood pressure. Decreased volume results in decreased blood pressure. Increasing volume increases stroke volume.

Hypertension: High BP.

Hypotension: Low BP.

Systole and Diastole

Blood pressure peaks during heart contraction (systole); this measure is the systolic blood pressure (SBP). Pressure reaches its lowest when the heart relaxes (diastole); this measure is the diastolic blood pressure (DBP).

Pulse pressure: Difference between the systolic and diastolic readings.

Too narrow indicates that the arteries are not properly relaxing between heartbeats, due to a condition such as arteriosclerosis. Too wide indicates the vessels may not have enough elasticity or tension to sustain adequate blood flow.

Mean arterial pressure (MAP): Mathematically approximation of the diastolic pressure plus 1331​ of the pulse pressure. Denotes the average pressure within the arteries.

MAP=DBP+13(SBP−DBP)MAP=DBP+31​(SBP−DBP)

Normal Blood Pressure

The normal difference between systolic and diastolic pressures is approximately one-third to one-half of the systolic pressure. Average systolic pressure for a twenty-year-old is approximately 115-120; average diastolic pressure is approximately 75-80. In a person with a BP of 120/80, the pulse pressure is 40 (1331​ the systolic). Some people have a naturally low BP, safe if around 100/60. Any pressure much higher than the recommended values (hypertension) is a sign of a circulatory problem. Very low BP (hypotension) may indicate hemorrhage or shock. A systolic reading <60 indicates serious difficulty. A diastolic reading >90 is considered dangerously high. Medications can cause variations - antihypertensive medications can cause lower blood pressure. Normal blood pressure in a child varies with age. Blood pressure may increase gradually with age due to aging of the heart and arteries. Direct measurement of BP - insertion of a probe or catheter into the patient's artery. Catheter tip has special sensors that measure pressures and transmit this information electronically. Automated BP and VS monitoring can also be accomplished indirectly, using a traditional blood pressure cuff and a less-sophisticated electronic machine. The cuff inflates and deflates automatically, and the values are digitally displayed on the screen. Many machines can be set to keep a record of the readings.

Sphygmomanometer

Blood pressure can be measured indirectly with a sphygmomanometer. It consists of an inflatable bladder, enclosed in a cuff attached to a bulb or a pump. The cuff is wrapped around the arm. Cuffs must be sized correctly for accurate compression of the artery and BP measurement. Indirect BP can be obtained with an aneroid sphygmomanometer by listening to the heartbeat with a stethoscope. The stethoscope is placed over the brachial artery and magnifies the sound of the heartbeat within the arteries. Occasionally, you may see a mercury manometer in a patient's home. The placement of the arm wrap is the same for all types.

Aneroid Manometer

With an aneroid (spring-type) manometer, the arm wrap is attached to a dial where pressure readings are observed. Emergency systolic pressure estimates can be taken since the heartbeats can be seen as the needle bounces.

Electric Blood Pressure Apparatus

Measures BP via a sensor or microphone in the cuff and provides a digital display of the patient's BP. Many of these machines are automatic. The cuff is wrapped, a button is pushed, and the machine pumps up the cuff and displays BP, pulse, and mean arterial pressure. The cuff is applied in the same manner as the aneroid manometer. In some situations, an automatic blood pressure cuff cannot be used - movement disorders or tremors will prevent the cuff from registering (e.g., Huntington's disease, specific medications).

Palpation

When a stethoscope is unavailable, blood pressure can be estimated using the aneroid manometer and by palpating pulsations of the artery as pressure is released from the cuff. Estimate the systolic pressure when the pulsation is first felt. You will also be able to visualize pulsations on the aneroid dial. Can usually only estimate the systolic pressure. Palpation may be the only technique for estimating BP if the patient is in hypovolemic shock, which sounds aren't audible. Electronic BP measurement is usually more accurate.

Doppler Ultrasound

If sounds are difficult to hear or indistinct, a Doppler ultrasound, instead of the stethoscope, may be used to amplify sounds. Similar to palpation, only the systolic pressure can be obtained using this method of determining blood pressure. Whenever BP is measured with a manometer, listen to the heartbeat through the stethoscope and watch the manometer at the same time. When the cuff deflates, blood returns through the artery. Korotkoff's sounds are heard in the stethoscope. There are five phases.

🩺 Assessing Vital Signs and Patient Data

Blood Pressure Measurement

Korotkoff's Phases

• Phase I: Onset indicates recorded systolic pressure.

• Phase IV: Onset indicates recorded diastolic pressure in children.

• Phase V: Onset indicates recorded diastolic pressure in adults.

Procedure

1. Ensure the patient is resting and quiet.

2. Explain to the patient that the cuff may feel tight briefly.

Alternative Site

• If arm measurement is impossible (e.g., IV, post-mastectomy), use a thigh cuff.

• Wrap the cuff at mid-thigh with the bladder in the back.

• Auscultate over the popliteal artery behind the knee.

Orthostatic Blood Pressure

• Monitor for drastic drops in BP or increase in pulse when changing positions.

• Report a drop of 25 points systolic or 10 points diastolic.

Orthostatic or postural hypotension: A condition occurring with a severe drop in BP.

Pulse Oximetry

Oximetry: A noninvasive procedure that measures the amount of light transmitted or reflected by deoxygenated versus oxygenated hemoglobin.

• Measures oxygen saturation of functional hemoglobin in the blood.

• A sensor is placed on a finger, toe, or earlobe.

• A healthcare provider orders the minimum acceptable level of oxygen saturation before using supplemental oxygen.

📝 Nursing Assessment: Data Collection and Analysis

Nursing Assessment: A systematic and continuous collection and analysis of information about a patient.

• Begins with collecting data to identify existing problems or needs.

• Existing needs take priority over potential needs.

Data Collection

• Best sources: patient and family.

• Consult the healthcare team, records, lab reports, and reference books.

• Physical examinations are also crucial.

Types of Data

TypeDefinitionExamplesObjectiveMeasurable and observable information about the patient's health.Vital signs, height, weight, urine volume, lab tests.SubjectivePatient's opinions or feelings about their condition.Pain, fear, feelings communicated through body language.

Methods of Data Collection

Observation

Observation: Using the five senses to gather information about the patient.

• Visual: Appearance, movements, expressions, dress, interactions.

• Tactile: Touch to assess muscle strength, temperature, moisture, edema, rash.

• Auditory: Hearing, using equipment (auscultation).

• Olfactory/Gustatory: Sense of smell to identify odors related to the patient's condition.

Health Interview/Nursing History

• Includes admission interview and medical history.

• Use open-ended questions to effectively plan personalized care.

Components of the Nursing History

• Biographical data: Name, age, address, occupation, etc.

• Reason for visit: Chief complaint (CC) or perception of illness.

• Recent health history: Symptoms, treatments, exposure to diseases.

• Important medical history: Family history, allergies, immunizations, medications.

• Psychosocial information: Family relationships, employment, living conditions, substance use.

• Activities of daily living (ADL): Eating, bathing, dressing, toileting.

Data Analysis

1. Examine information to determine relevance to the client's health problems.

2. Recognize significant data.

3. Validate observations.

4. Recognize patterns or clusters in symptoms.

5. Identify strengths and problems in coping.

Conclusions

1. No problem: No further nursing care is needed.

2. Potential problem: Gather more information.

3. Risk for a problem: Potential nursing diagnosis; continue with the nursing process.

4. Clinical problem: Nursing or medical diagnosis.

🩺 Nursing Diagnosis and Care Planning

Nursing Process Steps

1. Data Collection (Nursing Assessment)

2. Identifying the nursing care problem (Nursing Diagnosis)

3. Planning client care based on identified problems

Nursing Diagnosis: A statement about the actual/potential health concerns of a client that can be managed through independent nursing interventions.

History of Nursing Diagnosis

• 1973: Nurse researchers began plans to standardize communication.

• 1982: North American Nursing Diagnosis Association (NANDA) formed.

• 2002: Revised as NANDA-International (NANDA-I).

Components of a Nursing Diagnostic Statement

1. Problem: General label.

2. Etiology: Specific, related factors.

3. Signs and Symptoms: Specific, defining characteristics.

Example: Airway clearance is ineffective related to excessive mucus production as manifested by shortness of breath on exertion.

Two-Part Diagnostic Statement

Consists of problem and signs and symptoms.

Example: Airway clearance is ineffective manifested by shortness of breath on exertion.

Medical Diagnosis vs. Nursing Diagnosis

• Medical diagnosis: Identifies a disease; provides a basis for prognosis and medical treatment.

• Nursing diagnosis: Focuses on the individual's response to their health; directs nursing interventions.

Benefits of Nursing Diagnosis

• Identifies nursing priorities.

• Provides a common language for healthcare professionals.

• Guides the formulation of expected outcomes.

• Provides a basis for evaluation.

• Helps in making staff assignments.

Writing the Diagnostic Statement

• Link problem and etiology with "related to" (R/T).

• Link etiology and signs/symptoms with "as evidenced by" (AEB).

Planning Care

• Development of goals to prevent, reduce, or eliminate problems.

• Identify nursing interventions to assist clients in meeting goals.

Setting Priorities

• Survival needs are highest priority.

• Safety needs are next priority.

• Client also determines priority of health outcomes.

Expected Outcomes

Measurable client behavior that indicates whether the person has achieved the expected benefit of nursing care.

Characteristics:

• Client-oriented

• Specific

• Reasonable

• Measurable

Types:

• Short-term objective: Expected outcome within hours/days.

• Long-term objective: Goal that will take longer to accomplish.

Selecting Nursing Interventions

• Activities that will likely produce desired outcomes.

• Examples include further assessment, client teaching, or referral.

Writing a Nursing Care Plan

• The formal guideline for directing nursing staff to provide client care.

• Includes nursing diagnoses, expected outcomes, and nursing orders.

• An ever-changing guide updated regularly.

Nursing Care Plan Format

1. Written on a general information system (Kardex-type file).

2. Part of a client's computerized health record.

If a nursing care plan does not exist within 12 to 24 hours of the client's admission, the healthcare facility will be cited for noncompliance.

📏 Systems of Measurement and Dosage Calculation

Metric System

• Most widely used measurement system in the world.

• Based on meter (length), gram (weight), and liter (volume).

Prefixes

PrefixMeaningdeci-divide by 10; 1/10centi-divide by 100; 1/100milli-divide by 1,000; 1/1,000micro-divide by 1,000,000; 1/1 millionthdeca-multiply by 10; x 10hecto-multiply by 100; x 100kilo-multiply by 1,000; x 1,000

Metric Symbols

UnitAbbreviation/SymbolMilligrammgGramgKilogramkgMicrogrammcgLiterLMillilitermL

Conversions

• 1 kg = 2.2 pounds

• 1 ounce = 28.35 grams

• Large to small: Move decimal point to the right.

• Small to large: Move decimal point to the left.

Ratio and Proportion

• Ratio: Relationship of one quantity to another (e.g., 2/3 or 2:3).

• Proportion: Two equal ratios (e.g., 2/3 = 6/9).

Rules

1. Product of the means equals the product of the extremes.

2. Product of the means divided by one extreme yields the other extreme.

3. Product of the extremes divided by one mean yields the other mean.

4. Whatever is done on one side of the "=" sign must be done on the other side as well.

Example

Prescription: 1 mg Haldol IM Medication available: 5 mg/1 mL How many mL should be given?

5 mg1 mL=1 mgX mL1 mL5 mg​=X mL1 mg​

X=0.2 mLX=0.2 mL

Formula Method

Desired amountAvailable dosage×QuantityAvailable dosageDesired amount​×Quantity

Example

Prescription: 1/4 mg clonazepam Medication supplied: 1/2 mg tablets How many tablets to give?

14 mg12 mg×1 tablet=14×21=24=12 tablet21​ mg41​ mg​×1 tablet=41​×12​=42​=21​ tablet

The nurse would give 1/2 tablet

Significant Figures

• Numbers that have practical meaning or dosages that can be measured.

• For example, if a dosage is prescribed as 1.325 mL and the syringe only measures to the nearest tenth, administer 1.3 mL.

Percentages

• Refers to the number per hundred (e.g., 20% equals 20 per hundred).

• To convert from percentage to fraction, the percent number becomes the numerator, and 100 is the denominator.

💊 Introduction to Pharmacology

Pharmacology: The science that deals with the origin, nature, chemistry, effects, and uses of medications.

• PharmD or Registered Pharmacist (RPh) licensed to prepare and dispense medications.

• Medication orders can be written by MD, DO, DDS, DMD, DVM, PA, NP, CRNA, or CNM.

Nursing Responsibilities

• "Do no harm."

• Teach clients about the desired and possible side effects of medications.

Regulatory Agencies

• U.S. Food and Drug Administration (FDA): Ensures medications are safe and effective.

• Health Canada: Canadian counterpart.

Controlled Substances Act

• Regulates the manufacture, prescription, and distribution of psychoactive medications.

• Enforced by the Drug Enforcement Agency (DEA).

• Controlled substances must be managed carefully and kept in a double-locked area.

Client Rights

• Right to know the name, action, and side effects of medications.

• Right to refuse medications (unless court order).

• Right to request the generic form of prescribed medications.

Medication Information

• Nurses are obligated to know the generic and trade name, classification, use, dosage, effects, and route of administration of any medication administered.

Medication Preparations

• Oral (by mouth)

• Topical (applied to the skin)

• Inhalable (inhaled)

• Injectable (via a needle)

• Transdermal (absorbed through the skin)

Medication Names

• Chemical name: Describes chemical composition.

• Generic name: Assigned by the first manufacturer.

• Official name: Name identified in USP or NF.

• Trade name (brand name): Copyrighted name assigned by the manufacturing company.

Medication Actions

• Agonist: Produces a desired response.

• Antagonist: Opposing effect.

• Synergistic (potentiating) effect: Enhances the effects of another medication.

Medication Forms

• Liquids

• Solids

• Semisolids

• Metered-dose inhalants

• Transdermal medications

Liquids

• Administered orally, parenterally, or topically.

• Syrup: Liquid with a sweetener.

• Tincture: Liquid containing alcohol.

• Instillations: Liquids put into the eye or ear.

• Irrigations: Flushing out a wound.

Solids

• Pills, tablets, capsules, caplets, liqui-gel capsules, gel, or chewing gum.

• Tablet: Compressed, spherical form.

  • Enteric-coated: Dissolves in the intestine, not the stomach.

• Capsule: Powdered or pellet form enclosed in a soluble material.

• Caplet: Tablet in the shape of a capsule.

• Liqui-gel: Liquid-filled capsule.

💊 Medication Forms

Semisolids

Semisolid medications are typically administered through rectal, vaginal, or urethral routes. They are designed to melt at body temperature and be absorbed through mucosa or skin.

Inhaled Medications and Nasal Sprays

Oral or nasal inhalers and nebulizers deliver medications topically to the desired area, such as the lung or nasal mucosa.

• Inhalers: Aerosol (metered-dose inhaler [MDI]) or non-aerosol powder inhaler (Turbuhaler, Diskus).

• Nebulizer: Delivers liquid medication as a mist and provides topical administration to the lung tissue, reducing systemic side effects. Nebulization can take up to 5 minutes per dose.

Transdermal Medications

Transdermal (TD) medications are absorbed through the skin into the body via a patch or paste. This route is useful for medications that the GI system would destroy.

Injectable Medications

Administered by needle into tissues or blood vessels, or by catheter into a blood vessel.

• Intradermal: Within the layers of the skin

• Subcutaneous: Under the skin, into the subcutaneous tissue layer

• Intramuscular (IM): Into the muscle tissue

• Intravenous (IV) or Intra-arterial (IA): Into the blood vessels

• Intrathecal: Into the area surrounding the spinal cord

📝 Prescribed Medications

• Dose: A single amount of medication administered to achieve a therapeutic effect

• Dosage: Includes the dose and scheduled times (e.g., 250 mg, three times a day)

• Therapeutic Dose: Amount of medication required to obtain a desired effect in most clients

A blood sample may be taken to determine the client's blood level of a drug to help establish the therapeutic dose.

• Minimal Dose: Smallest amount of drug necessary to achieve a therapeutic effect

• Loading Dose: Larger initial dose to establish a minimum blood level

• Maximal Dose: Largest amount that can be given safely without causing an adverse reaction

• Toxic Dose: Amount of medication that causes symptoms of poisoning or toxicity

• Lethal Dose: Amount that will cause death

factors that affect medication prescription

Age

Children and older adults may not tolerate standard adult dosages due to differences in size, metabolism, and organ function.

Gender

Differences in body fat and fluid levels between men and women can affect medication effects. Women generally require smaller doses than men.

Weight

Dosage is often prescribed in relation to a client's weight; heavier clients may require larger dosages.

Client's Condition

The nature and severity of a disease can influence the prescribed dosage.

Disposition and Psychological State

Personality and culture can affect the amount of medication needed.

Method of Administration

The administration route affects how quickly the medication enters circulation. IV and IM injections act more rapidly than oral medications.

Distribution

Medications may distribute evenly or only reach certain body fluids or tissues.

Environmental Factors

Temperature can influence a medication's speed of absorption.

Time of Administration

Medications taken with meals may be absorbed more slowly than those taken on an empty stomach.

Elimination

The body eliminates medications through urine, feces, breath, and perspiration.

📜 Prescriptions

• Prescription (Medication Order): A written or verbal formula for preparing and giving a medication.

• Legend Drug: Requires a prescription.

• Over-the-Counter (OTC) Drugs: Can be purchased without a prescription.

Verbal medication orders must be read back to the primary provider and can only be taken by licensed nurses.

💊 Classifications of Medications

Medications are grouped based on similar actions on a body system, which may also result in similar adverse effects (cross-sensitivity).

Interactions Between Food and Medications

Some medications interact negatively with certain foods, potentially causing toxicity. Some medications should be taken with food, while others should be taken on an empty stomach.

Interactions Between Drugs (Drug-Drug Interactions)

Using two or more drugs can lead to decreased effectiveness or overdose. Always consult a pharmacist or drug reference if unfamiliar with the drugs being administered.

🦠 Anti-Infective Agents and Antibiotics

• Anti-Infective Agent: Medication used to treat an infection

• Antibiotic: Chemical compound used to treat bacterial infections

Antibiotic Classifications

• Broad-Spectrum: Effective against many organisms

• Narrow-Spectrum (Specific): Effective against only a few microorganisms

• Bacteriostatic Agents: Slow the growth of bacteria

• Bactericidal Agents: Kill bacteria

Considerations for Antibiotic Effectiveness

• Soluble in water

• Diffuses readily into body tissue

• Does not cause adverse or allergic reaction

• Does not affect normal flora

• Well absorbed by the GI tract

• Not antagonistic to other antibiotics

Antibiotic Resistance

Pathogens may mutate or build a tolerance to an antibiotic if it is used indiscriminately or administered improperly.

Culture and Sensitivity (C&S) Test

Used to determine the specific microorganism causing an infection and the medication to which the organism is most sensitive. Antibiotic therapy should not start until after the specimen for C&S is obtained.

Common Antibiotics

Penicillins Cephalosporins Tetracyclines Aminoglycosides Macrolides Sulfonamides

Penicillins (PCN)

Derived from a specific mold, penicillin inhibits the growth of susceptible bacteria and is bactericidal in high concentrations. It is most effective against gram-positive organisms and some gram-negative organisms. Common side effects include allergic reactions.

Cephalosporins

Similar to penicillin and divided into first, second, and third generations based on specificity. They are frequently used for mixed infections and have minimal adverse effects, but may cause GI symptoms. Avoid alcohol while taking cephalosporins to prevent severe nausea and vomiting.

Tetracyclines (TCN)

Broad-spectrum antibiotics used in clients who are allergic to penicillin. Absorption is decreased by food and dairy products. Side effects include nausea, vomiting, diarrhea, photosensitivity, and brownish discoloration of developing teeth. Contraindicated for pregnant women and young children.

Aminoglycosides

Potent bactericidal antibiotics used for hospital-acquired gram-negative infections and preoperatively for GI tract surgery. They are most often administered parenterally. Toxic effects include ototoxicity and nephrotoxicity.

Macrolide Antibiotics

Narrow-spectrum bacteriostatic agents used to treat respiratory tract infections in clients who are allergic to PCN. Adverse reactions include skin rashes, abdominal pain, nausea, and cramping.

Sulfonamides

Used as antimicrobial agents due to low cost and effectiveness in treating common bacterial infections. They are bacteriostatic agents. Encourage clients to drink large amounts of fluids. Adverse reactions include nausea, vomiting, diarrhea, electrolyte imbalance, cyanosis, or jaundice.

🧠 Medications Affecting the Nervous System

Medications can be used to increase or decrease the activity of vital nerve centers in the brain or nerve pathways.

• Stimulants: Speed certain mental and physical processes

• Depressants: Slow certain mental and physical processes

Analgesics

Medications that relieve pain.

Divided into two groups: narcotics and non-narcotics.

Narcotic Agonist Analgesics

Called opiates because they are opium derivatives or have opium-like actions. They are potent, highly addictive, and subject to narcotic regulation.

Morphine Sulfate

A very potent narcotic analgesic used to relieve severe pain and produces a feeling of well-being, reducing fear and anxiety. Common side effects include nausea, vomiting, constipation, and decreased respiratory rate.

Hydromorphone Hydrochloride (Dilaudid)

Prepared from morphine and has about five times its analgesic effect. It causes very little drowsiness, nausea, or vomiting but does depress respiration.

Codeine

A derivative of morphine with a milder action. It is effective in relieving cough and is a common ingredient in cough mixtures.

Nonnarcotic Analgesics

Less potent than narcotic analgesics and are available over the counter (OTC).

Salicylates

Derive from salicylic acid (SA). Acetylsalicylic acid (ASA, aspirin) is commonly used for mild to moderate pain. Actions include analgesic, antipyretic, anti-inflammatory, and mild anticoagulation.

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

Used primarily to treat inflammation, but also have analgesic and antipyretic actions. They can cause gastric upset and should be taken with food.

Hypnotics and Sedatives

• Hypnotic: Medication that produces sleep.

• Sedative: Medication that has a calming or quieting effect.

Anticonvulsants

CNS depressants that help prevent or control various types of seizure activity. Dosage is adjusted for each client, with gradually increasing dosages administered until the desired blood level is achieved or until seizure activity is controlled.

Examples include:

• Phenytoin

• Clonazepam (Klonopin)

• Carbamazepine (Tegretol)

• Diazepam (Valium)

• Magnesium sulfate

Adrenergic Medications

An adrenergic is epinephrine or a substance that acts like epinephrine.

Mimic the actions of the sympathetic division of the autonomic nervous system (ANS) and are referred to as sympathomimetics.

Catecholamines

Neurotransmitters that play an important part in the body's response to stress. They increase cardiac output, constrict peripheral blood vessels, increase blood pressure, and cause bronchodilation.

Epinephrine (Adrenaline)

Constricts peripheral blood vessels and controls capillary bleeding. It increases heart rate, raises blood pressure, constricts surface blood vessels, and relaxes smooth muscles in the respiratory tract, causing bronchial dilation. It is the medication of choice for the treatment of anaphylactic and hypersensitivity reactions.

Norepinephrine (Levarterenol, Levophed)

Increases blood pressure due to vasoconstriction of peripheral blood vessels, slowing the heart rate. It may be used to treat heart failure.

Noncatecholamines

Dopamine Hydrochloride (Dopamine)

Affects the contractility of heart muscle and increases blood pressure. Used to treat severe shock and hypotension.

🧬 Medications Affecting the Endocrine System

Hormone replacement therapy (HRT) is given to reduce symptoms caused by various hormonal deficiencies.

Insulin

Essential for carbohydrate metabolism. Various insulins have different lengths of onset and duration of action.

👁 Ophthalmic Medications

Include agents that dilate or constrict the pupil, antibiotics, and agents that reduce intraocular pressure.

• Mydriatics: Ophthalmic preparations used to dilate pupils.

• Miotics: Ophthalmic preparations used to constrict pupils.

• Ophthalmic Antibiotics: Used to treat eye infections.

👂 Medications Affecting the Ears

Commonly used medications include anti-infectives (to treat ear infections), analgesics (to treat the pain of otitis media), and cerumenolytics (to loosen and remove impacted earwax).

❤ Medications Affecting the Cardiovascular System

Medication TypeFunctionCardiotonicsStimulate or strengthen the heart's pumping action.AntiarrhythmicsRegulate heart rhythm.VasoconstrictorsConstrict or narrow the blood vessels.VasodilatorsDilate or widen blood vessels, often used to lower and control blood pressure.AntihypertensivesUsed to reduce blood pressure on an ongoing basis (diuretics, beta blockers, etc.).DiureticsIncrease the amount of urine excreted by the kidneys, lowering blood pressure.Beta BlockersDecrease heart rate and blood pressure.Calcium Channel BlockersReduce peripheral vascular resistance and lower blood pressure.ACE inhibitorsReduce peripheral vascular resistance by blocking the activation of angiotensin.ARBSSelectively block the binding of angiotensin II to specific receptors.

🩸 Medications Affecting the Blood

Assist in blood clotting or preventing clots from forming and serve to replace blood volume or components lost by events such as hemorrhage.

• Epoetin alfa (erythropoietin): Stimulates red blood cell production.

• Iron replacement preparations: Needed to ensure adequate daily intake of iron.

• Vitamin B12: Necessary for the manufacture of erythrocytes and healthy nervous system functioning.

• Folic acid: Stimulates production of RBCs and WBCs and is necessary for normal maturation of RBCs.

• Coagulants: Promote blood coagulation.

• Anticoagulants: Increase the time it takes blood to coagulate.

⚔ Antineoplastic Medications

Used as a palliative measure for tumors that are no longer curable by surgery or for cancers such as leukemia that spread throughout the body.

• Alkylating agents

• Antineoplastic antibiotics

• Antimetabolites

• Antimitotics

• Hormonal agents

• Corticosteroids

• Antiangiogenics

🤧 Antihistamines

Most effective in relieving the uncomfortable symptoms of allergic rhinitis and chronic urticaria (itchy rash). Common side effects include drowsiness, decreased mental alertness, dry mouth, dizziness, confusion, and constipation.

😮‍💨 Medications Affecting the Respiratory System

Include bronchodilators, corticosteroids and antiasthmatic medications, respiratory stimulants, antitussives, expectorants, antihistamines, and decongestants.

• Bronchodilators: Relax the smooth muscles of the tracheobronchial tree, thereby dilating (increasing) the size of the lumen.

• Respiratory stimulants: Stimulate deeper respirations and increase the rate of respiration.

🫄 Antacids

Used to treat common "upset stomach." They are also used to reduce

Medications Affecting the Gastrointestinal and Urinary Systems 💊

Medications for Stomach Acidity and Ulcers

• Histamine (H2) antagonists:

  • Inhibit gastric secretions mediated by histamine.

  • Used for ulcers, gastric reflux, and hypersecretory conditions.

• Proton pump inhibitors:

  • Inhibit gastric acid secretion in its final stage.

  • Used for ulcers and gastroesophageal reflux disease (GERD).

Other Gastrointestinal Medications

• Antitussives: Used to relieve cough (narcotic and non-narcotic types).

• Antiflatulents: Treat symptoms of excess gas in the digestive tract.

• Antispasmodic agents:

  • Ideally reduce gastric secretions and slow GI motility.

  • Associated with adverse effects like blurred vision, dry mouth, and rapid heart rate.

• Emetics: Agents that induce vomiting.

• Antiemetics: Provide symptomatic relief from nausea and vomiting.

• Cathartics (laxatives): Used to relieve constipation.

• Fecal softening agents:

  • Act like detergents to mix water and fatty material with fecal contents.

  • Cause stools to become moist and bulky, stimulating the bowel.

• Antidiarrheal agents: Slow GI peristalsis and stop diarrhea while allowing normal bowel movements.

Diuretics 💧

• Diuretics: Rid the body of excess fluids by increasing urine formation.

• Thiazide diuretics:

  • Synthetic medications related to sulfonamides.

  • Advantages: ease of administration (oral), low cost, effectiveness over long periods, low toxicity, and few side effects.

• Loop diuretics: Inhibit reabsorption of sodium and chloride in the loop of Henle in the kidney.

Medications for Bladder Dysfunction and Enuresis

• Neostigmine methylsulfate (Prostigmin) and Bethanechol chloride (Urecholine): Improve bladder muscle tone.

• Oxybutynin (Ditropan): An antispasmodic used for bladder dysfunction with urinary frequency.

• Desmopressin acetate (DDAVP):

  • A hormone administered as a nasal spray or orally.

  • Used at bedtime to treat enuresis (bed wetting).

  • Also used to treat excessive voiding of diabetes insipidus.

Urinary Antiseptics and Antibiotics 🧫

• Urinary antiseptics: Treat bacterial infections of the urinary tract.

• Commonly used:

  • Co-trimoxazole (Bactrim)

  • Tetracyclines

  • Erythromycin

  • Fosfomycin (Monurol)

  • Ciprofloxacin (Cipro)

  • Cinoxacin (Cinobac)

  • Nitrofurantoin (Furadantin)

• Phenazopyridine: Provides prompt analgesic effects.

Androgens and Estrogens 👩‍⚕

• Androgens:

  • Essential for the development and maintenance of male sex characteristics.

  • Used in androgen replacement therapy for men with insufficient hormone levels.

  • May slow the growth of estrogen-dependent tumors in women.

• Estrogen replacement therapy:

  • Benefits: Prevents osteoporosis and other tissue changes associated with menopause and may postpone cardiovascular changes of aging.

  • Side effects: Edema, thromboembolism, abdominal cramping, anorexia, bloating, nausea, vomiting, hepatitis, breast tenderness, and breakthrough bleeding.

  • Available in oral, parenteral, and transdermal routes.

• Progesterone:

  • Prepares the uterine lining for ovum implantation.

  • Suppresses ovulation during pregnancy.

  • Reduces irritability of uterine muscle to prevent premature labor or spontaneous abortion.

Oral Contraceptives and STI Treatments

• Oral contraceptives:

  • Hormonal preparations containing estrogen and progesterone to prevent pregnancy.

  • Estrogen suppresses ovulation by affecting the release of follicle-stimulating hormone (FSH).

  • Side effects: Nausea, vomiting, breast tenderness, headache, nervousness, emotional lability, and venous thrombosis (blood clots).

• Antibiotics: Used to treat many sexually transmitted infections (STIs), including syphilis and gonorrhea.

• Antiviral agents:

  • Used to treat viral STIs, such as herpes.

  • Examples: Acyclovir sodium (Zovirax) or zidovudine (Retrovir).

  • Acyclovir and zidovudine are also used to treat HIV and AIDS.

Erectile Dysfunction Medications

• Commonly used medications:

  • Sildenafil (Viagra)

  • Vardenafil (Levitra)

  • Tadalafil (Cialis)

• Herbal supplements are also available.

Medication Storage, Supply, and Documentation 🏥

Medication Storage and Supply

• Healthcare facilities have a "med room" or separate storage area for medications.

• Some medications require refrigeration in a special med room refrigerator.

  • The temperature must be monitored and documented daily.

• Stock supply medications: Over-the-counter (OTC) medications that are kept locked until needed.

• Unit-dose systems: Medications supplied in individual prepackaged containers.

• Automated systems: Computerized systems for dispensing medications.

• Self-administered medication: Kept at the bedside of responsible clients.

Documenting Medication Administration

• All nurses must know how their facility stores and supplies medications.

• Important to accurately document whether the client did or did not receive medications.

Types of Medication Orders

• STAT: Immediately

• PRN: As needed

• Bedtime medications: Medications given before sleep

The "Six (Seven) Rights" of Medication Administration

1. Right patient

2. Right medication

3. Right dose

4. Right route

5. Right time

6. Right documentation

7. Right reason

Identifying a Client Before Giving Medications

• Follow facility-approved means of identification before administering medications.

Desired vs. Undesired Effects

• Desired effects: The intended therapeutic effects of the medication.

• Undesired effects: Side effects or adverse reactions.

Local vs. Systemic Medication Effects

• Local effects: Effects that occur at the site of administration.

• Systemic effects: Effects that occur throughout the body.

Enteral vs. Parenteral Administration

• Enteral administration: Medication given through the digestive tract.

• Parenteral administration: Medication given by any other route than the digestive tract

Methods of Enteral Medication Administration 💊

Oral Administration

• Includes translingual, sublingual, and buccal methods.

  • Translingual: Medication is applied to the tongue.

  • Sublingual: Medication is placed under the tongue.

  • Buccal: Medication is placed between the gum and cheek.

Administration via NG Tube

• Medication given through a nasogastric tube.

Rectal Administration

• Medication inserted into the rectum.

Administration of Other Medication Types

• Transdermal: Medication applied to the skin.

• Vaginal: Medication inserted into the vagina.

• Eye/Ear: Medication administered to the eyes or ears.

• Aerosolized: Medication inhaled as a mist.

Nutrition and Diet 🍎

Basic Component of Health

• Nutrition is a basic component of health that impacts a patient's rate of recovery from illness and injury.

Malnutrition

• Develops due to lack of attention to nutritional status, resulting in decreased intake of nutrients, increased nutrient requirements, or complications associated with a disease process.

• Complications include muscle wasting, delayed wound healing, increased susceptibility to skin breakdown and infection.

Nutritional Screening

• Identifies if individuals are malnourished or at risk for malnutrition.

• The Joint Commission (TJC) standards require the identification of patients who are nutritionally at risk by means of an initial screening mechanism.

• Screening must be done within 24 hours of admission to a hospital or within 14 days of admission to a long-term care facility.

Risk Factors for Malnutrition

• Clear- or full-liquid diets for more than 3 days without nutrient supplementation

• Intravenous feeding (dextrose or saline) or NPO for more than 3 days without supplementation

• Low weight intakes of prescribed diet or tube feedings

• Weight 20% above or 10% below desirable body weight (accounting for edema)

• Pregnancy weight gain deviating from normal patterns

• Diagnoses that increase nutritional needs or decrease nutrient intake:

  • Cancer, malabsorption, diarrhea, hyperthyroidism, excessive inflammation, postoperative status, hemorrhage, infected or draining wounds, burns, infection, major trauma

• Chronic use of drugs, especially alcohol, which affects nutritional intake

• Alterations in chewing, swallowing, appetite, taste, and smell

• Body temperature consistently above 37°C (98.6°F) for more than 2 days

• Hematocrit:

  • <43% in men

  • <37% in women

• Hemoglobin

  • <14 g/dL in men

  • <12 g/dL in women

• Absolute decrease in lymphocyte count (<1500 cells/mm3)

• Elevated (>250 mg/dL) or decreased (<130 mg/dL) total plasma cholesterol

• Serum albumin <3g/dL in patients without renal or liver disease, generalized dermatitis, or overhydration

Nutritional Assessment Tools

• Subjective Global Assessment (SGA): Evaluates the presence of malnutrition in patients with different disease conditions.

• Malnutrition Universal Screening Tool (MUST): Assesses older adults to detect malnutrition, at-risk for malnutrition, and obesity in five steps; also provides management guidelines.

• Mini Nutritional Assessment (MNA):

  • Nutritional screening tool for the elderly (>65 years old) in long-term care facilities to identify malnutrition or early malnourishment.

  • Accounts for mobility, stress, BMI, arm and calf circumference, eating habits, and medical history.

• Nutrition Care Process (NCP): Comprehensive evaluation done by a registered dietician (RD).

Dietary Guidelines

• Dietary guidelines for Americans: Released in 2021; targets individuals 2 and older to promote health, reduce risk of chronic disease, and prevent and reverse obesity through nutrition and physical activity.

• MyPlate Food Guidance System:

  • Replaced MyPyramid; illustrates five food groups in a single meal.

  • Recommend half a plate of fruits and vegetables, lean protein with seafood twice a week and whole grain, and including dairy.

Cultural Considerations in Nutrition

• Make attempts to provide patients with nutritional foods familiar and congruent with their beliefs.

  • Buddhists and Hindus: Generally vegetarians

  • Muslims: Eat halal food and avoid foods classified as haram

  • Orthodox Jews: Eat kosher foods and avoid serving meat and dairy at the same time. They eat fish with fins and scales, animals that chew their cud, and non-predatory birds. Shellfish cannot be eaten.

• Muslims: Fast all day, including food and water, during the month of Ramadan. They eat before dawn and during evenings.

Nutritional Assessment and Implementation 🩺

Patient History in Nutritional Assessment

• Elements such as appetite, psychosocial factors affecting intake, economics, and cultural issues provide a background for factors influencing current nutritional status.

• Social history provides insight into poverty, avoidance of specific food groups, and food customs influencing nutritional education.

Physical Examination

• Nutritional-focused physical examinations can identify nutritional deficiencies not identified by other assessment approaches.

Anthropometric Measurements

• Use body composition measurements to describe nutritional status: e.g., height, weight, skinfold thickness, waist and muscle circumference.

• % Weight change: % Weight change=(Usual weight−Actual weight)Usual weight% Weight change=Usual weight(Usual weight−Actual weight)​
  Time PeriodModerate Weight LossSevere Weight Loss1 week1-2%>2%1 month5%>5%

BMI

• Ratio of weight to height and associated with overall mortality and nutritional risk. BMI=Weight (lb)Height (inches)2×703BMI=Height (inches)2Weight (lb)​×703

• BMI and waist circumference used to estimate body fat distribution—circumference greater than 40 inches for men and 35 inches in women corresponds with increased cardiovascular risk.

Biochemical Markers of Nutritional Status

• Typically, serum albumin and prealbumin levels used to measure visceral protein status.

Delegation and Collaboration

• Nursing assistive personnel (NAP) take measurements of height and weight but do not interpret the results.

Equipment Assessment

• Sheet and pen or computerized system.

Medications and Dietary Supplements

• Determine medications and other dietary supplements.

• Medications can inhibit the action of other medications (e.g., vitamin K-rich foods interfere with warfarin, and mineral oil laxatives impair nutrient use).

Therapeutic Diets

• Clear-liquid: Foods that leave little residue and are easily absorbed.

• Full-liquid: Includes foods of clear-liquid diet plus smooth-textured dairy products.

• Pureed: Includes clear- and full-liquid diet plus easily swallowable foods (scrambled eggs, mashed potatoes); ordered for patients with head and neck abnormalities; can be modified for low sodium, fat, or calorie count.

• Mechanical or dental-soft: Includes all previous diets; includes ground and finely diced meats, fish, and cheese. For patients with chewing problems or mild GI problems.

• Soft/low-residue: Addition of low-fiber, easily digested foods that are easy to chew and simply cooked. Does not permit fatty, rich, and fried foods.

• High-fiber: Addition of fresh uncooked fruits, and steamed vegetables.

• Sodium-restricted: 4-g (no added salt), 2-g (moderate), 1-g (strict), 500 mg (very strict) diet. For patients with heart failure, renal failure, cirrhosis, or hypertension.

• Fat-modified: Limits total and saturated fat and low cholesterol level intake to less than 300 mg daily, and fat intake to 30% to 35%.

• Diabetic: Provide patients with a diet recommended by the American Diabetes Association.

Patient Assessment Questions

• Ask the patient to report usual body weight (UBW), noting any recent changes and if the change was intentional or unintentional.

• Obtain a complete nursing history, including socioeconomic and psychological factors to determine patients' current nutritional habits.

• Perform a physical assessment, including the condition of the skin, hair, nails, oral mucosa, muscle mass, and strength.

• Determine both over-the-counter and prescribed medications and supplements.

• Measure actual body weight (ABW).

Measuring Height and Weight

• Have the patient void to increase accuracy of actual weight.

• Record weight to the nearest 0.25 lb (0.1 kg).

• Measure actual height.

• Have the patient stand with weight equally distributed on both feet.

• Instruct the patient to let arms hang free at sides with palms facing thighs to prevent movement of shoulders.

• Measure to the nearest 0.1 cm (1/8 inch).

Calculating Ideal Body Weight (IBW)

• Calculated via standard height and weight chart.

• IBW range for normal is 10% above and 10% below IBW.

• For Males: 106 lbs(48.1 kg) for first 5 feet+6 lbs(2.7 kg) per additional inch106 lbs(48.1 kg) for first 5 feet+6 lbs(2.7 kg) per additional inch

• For Females: 100 lbs(45.4 kg) for first 5 feet+5 lbs(2.25 kg) per additional inch100 lbs(45.4 kg) for first 5 feet+5 lbs(2.25 kg) per additional inch

Assessing Diet History

• Assess patient's diet history, including current diet, food preferences, appetite, restrictions, allergies, and intolerances.

• Have the patient provide a 24-hour diet recall.

Special Considerations

• Gerontological:

  • Normal anthropometric standards are based on a healthy middle-aged population, so methods differ for older individuals.

  • Some older adults may have a diminished appetite due to loss of taste and smell and a decreased number of taste buds.

• Pediatric:

  • Length, weight, and head circumference must be included in anthropometric data.

  • Compare measurements with standard growth charts to determine percentiles for stature.

  • Human milk is the most desirable complete diet for infants during the first 6 months.

  • Breastfed or bottle-fed infants do not require additional fluids for the first 4 months of life.

  • Solid foods are not typically introduced until after 6 months.

  • A new food is introduced every 5-7 days—first fruits, then vegetables, and finally meats.

Monitoring Nutritional Intake

• Monitor input and output (I&O) and percentage of food on tray after meal.

• Observe the ability of the patient to self-feed, ability to feed, and body weight daily or weekly.

Dysphagia Screening and Management 👅

• Signs: Tachypnea, cough, dyspnea. Wet-sounding vocal quality is an indicator for silent aspiration of saliva.
  Silent aspiration refers to the passage of food and liquids into the trachea without producing a cough or other signs.

• Keep in close contact with the patient to identify swallowing difficulties.

• The single most important measure to prevent aspiration is to place the patient on NPO until a swallowing evaluation.

• Dysphagia Screening: Give the patient water or food and observe for coughing or gagging. Include accompanying fluid administration with pulse oximetry measurement.

  • Normal oxygen saturation is greater than 95%.

  • A drop in oxygen saturation greater than or equal to 2% is used to determine aspiration.

• Management: Alter the consistency of foods and liquids with four levels of diet: dysphagia puree, dysphagia mechanically altered, dysphagia advanced, and regular.

  • Thickened liquids are often prescribed to prevent aspiration pneumonia.

• Consequences: Malnutrition, dehydration, and pneumonia.

Enteral Tubes and Nutritional Support

• NG feeding tubes: Inserted into the small bowel at bedside in a procedure referred to as blind placement.

  • Complications include pulmonary intubation, occurring in 1-2% of NG tubes.

• Verifying feeding tube placement: Initial X-ray film variation. Monitoring the length of the tube and observing the appearance, volume, and pH of fluid aspirated.

• Nasoenteric, Gastrostomy, and Jejunostomy are three methods. Gastric feeding is the most popular.

Conditions Requiring Enteral Feeding

• Occurs in cases when normal eating is not safe due to a high risk of aspiration.

  • Examples: altered mental state, swallowing disorders, impaired gag reflex, esophageal conditions.

• Clinical conditions that interfere with normal ingestion or absorption: surgical resection of oropharynx, proximal intestinal obstruction or fistula, pancreatitis, burns, pressure ulcers.

• Feeding tubes are placed into the GI tract in patients who cannot tolerate nasoenteric feeding tubes or require long-term enteral nutrition.

• G-tubes (AKA PEG tubes): Used for feeding and exit through an incision in the upper left quadrant of the abdomen, where an internal and external bumper hold the tube in place.

• Jejunostomy tubes: Indicated when the risk of regurgitation and aspiration is especially high, such as delayed gastric emptying or limited use of the stomach for feeding.

Parenteral Nutrition (PN)

• Specialized form of nutritional support intravenously by an infusion pump to patients with significant GI dysfunction.

• Risk: Catheter-related bloodstream infections (CRBSI).

• Hospitalized patients who are allowed nothing by mouth (NPO) and have PN are at risk for sludge accumulating in the gallbladder, with potential complications such as acute cholecystitis.

• In-home long-term PN patients have reported developing metabolic bone disease.

• Venous access for administration: Concentrated PN solutions are quickly diluted when infused into a large-diameter central vein. Peripheral and midline veins should be avoided due to the risk of phlebitis.

Perioperative Nursing 🏥

Preoperative Assessment

• Perianesthesia nurse, nurse practitioner, and anesthesia provider interview the patient and/or family member.

• Take patient history, perform physical diagnostic testing, and provide preoperative education to prepare the patient.

• Complete informed consent permits.

• For same-day surgery, preoperative assessment is done several days prior to the surgery.

The Joint Commission Patient and Family Education Standards

• Education provided is appropriate to the patient's needs.

• Patients are educated about:

  • The plan for care, treatment, and services (e.g., postoperative monitoring).

  • Basic health practices and safety (i.e., out of bed [OOB] only with assistance).

  • The safe and effective use of medication (i.e., the patient is only one allowed to self-administer patient-controlled analgesia PCA).

  • Nutrition interventions, modified diets, or oral health (i.e., progression of diet after surgery).

  • Safe and effective use of medical equipment or supplies when provided by the hospital (e.g., incentive spirometer).

  • Pain management.

  • Habilitation or rehabilitation techniques to help them reach the maximum independence possible (Le., early ambulation).

• Preparatory Procedures:

  • Surgical skin preparation

  • Inserting an indwelling catheter

  • Nasogastric (NG) tube

• Protect patients from surgical risks and improve surgical outcomes.

Levels of Care

• American Society of PeriAnesthesia Nurses (ASPAN)

  • Postanesthesia phase I: Immediate Recovery:

    • Basic life-sustaining needs, continuous monitoring for airway clearance, cardiovascular complications, temperature control, and neurologic function.

    • Leaving the operating room to stabilization in PACU.

  • Postanesthesia phase II: Postoperative Convalescence:

    • Return the patient to the function level of wellness with supportive and preventive therapies.

    • Preparation for home care or extended care environment.

Evidence-Based Guidelines

• Evidence-Based Guidelines to reduce surgical site infections (SSIs) and promote surgical care improvement project (SCIP):

  • Do not remove hair unless it will interfere with the operation and remove it using only electric clippers if possible.

  • Give the correct antibiotic before surgery and at the appropriate time.

  • Maintain blood glucose level after surgery, especially for patients undergoing cardiac surgery.

  • Maintain normothermia (core temperature range: 36-38°C).

  • Receive a beta-blocker during the perioperative period.

  • Remove the urinary catheter on postoperative day 1 or 2.

Prophylactic Antibiotics

• Select the most effective antibiotics for maximum coverage.

• Administer antibiotics when they are most beneficial to protect patients from infection.

• Given as close to the time of incision as possible (within 60 minutes).

• Vancomycin and fluoroquinolones may be given up to 2 hours before incision due to longer infusion times.

• Antibiotics after incision close do not reduce infection rates.

• Antibiotics should be discontinued within 24 hours after the end of the surgery.

Postoperative Considerations

• Immediate postoperative glucose control to reduce the risk of surgical infection.

• Beta-blocker therapy pre- and post-surgery to prevent adverse cardiac events.

• Prophylactic pharmacologic and mechanical therapies to prevent venous thromboembolism (VTE).

• Overweight or obese patients are at higher risk of postoperative complications (e.g., obstructive sleep apnea).

• Monitoring patients in the postanesthesia care units (PACUs).

  • Continuous pulse oximetry for 24 hours

  • Deep-breathing exercises

  • Limit opioid medications.

Safety Guidelines

1. Take a history of previous surgeries that may contribute to anatomic and physiologic alterations.

2. Identify conditions that increase the risk of perisurgical complications.

3. Understand the rationale for the surgical procedure and the type of nursing care required.

4. Witness informed consent from the patient.

5. Complete the preoperative checklist and the WHO Surgical Safety Checklist.

6. Administer pain medications.

7. Restrict patient activity to prevent falls.

Do Not Resuscitate (DNR) Orders

• The surgeon is responsible for discussing whether to maintain the DNR order during surgery.

• Detail resuscitation efforts that may be required during surgery.

• Consider whether withholding resuscitation would align with the patient's goals.

• Create advance directives to be included with the patient's chart.

• Ensure there is clear documentation in the medical record about the DNR order.

Food and Fluids

• Patients routinely undergo fasting prior to surgery to minimize the risk of aspiration.

• Food and fluids generally withheld 8 hours before surgery requiring general anesthesia.

• NPO may be required for spinal or epidural anesthesia.

• Hypotensive patients can receive intravenous fluids.

• Medications to decrease respiratory and gastrointestinal secretions.

• Encourage patients to stop nicotine usage at least 30 days prior to surgery.

Universal Protocol for Preventing Wrong Site, Wrong Procedure, Wrong Person

• Protocol to verify person, procedure, and surgical site prior to surgery, at the time of:

  • Scheduling procedure

  • On admission

  • Patient transfer

• Check with the entire surgical team before the procedure.

• Final verification with surgical team and patient (awake and aware), including site markings.

• Confirm patient position and availability of special equipment.

• Documentation of the final verification process.

Special Considerations

• Pediatric Patients:

  • Allow both parents and children to participate in pre-operative preparation.

  • Allow children to handle equipment (i.e., anesthesia mask or drainage tube) to get comfortable.

  • Explain the preoperative procedures based on the developmental level of the child.

  • Allow parents to accompany the child in the holding area and/or PACU.

• Geriatric Patients:

  • The patient may require admission to the hospital prior to the procedure for diagnostic tests and stabilization.

  • Perform when the patient is awake and alert; provide short teaching sessions related to surgery preparation or aftercare.

  • Take into account age-related conditions (i.e., decreased vision, hearing, short-term memory).

  • Ensure there is a caregiver to take ambulatory patients home.

• Home Care:

  • Instruct patients on pre-operative preparation (i.e., NPO status, skin preparation, enemas/douches).

  • Ensure ambulatory patients are accompanied for discharge.

Postoperative Exercises

• Effective coughing, deep/diaphragmatic breathing, turning, and leg exercises using an incentive spirometer to prevent circulatory and respiratory complications.

• Incentive spirometry for chronic smokers or patients on prolonged bed rest who have an increased risk of atelectasis or pneumonia.

• Positive expiratory pressure (PEP) therapy as an alternative to conventional physiotherapy.

• Include caregivers in the teaching/practice sessions.

• Early ambulation and leg exercises to prevent the formation of deep vein thrombosis (DVT).

• Compression stockings, intermittent pneumatic compression devices, venous plexus foot pump, etc.

The Surgical Team 👨‍⚕👩‍⚕

• Surgeon (MD/DO)

• Physician's assistant (PA)

• Registered nurse first assistant (RNFA)

• Certified registered nurse anesthetist (CRNA)

• Physician anesthesiologist (MD/DO)

• Circulating nurse (RN)

• Scrub nurse/technician (RN/licensed practical nurse- LPN/certified surgical technologist - CST)

Roles of a RN in the OR

• First assistant to the surgeon (RNFA): assist the surgeon with the procedure and delegates medical functions

• Scrub nurse/technician: sterile member who provides instruments to the surgeon

• Circulating nurse: charge nurse in the room, nonsterile member who is responsible for patient safety and continuity of care

• Sterile Conscience: Knowledge of aseptic technique, self-discipline, communication to identify, address, and correct breaks in sterile technique

Role of a Circulating Nurse

• Incorporates nursing process in the plan of care

• Organizes and prepares OR before the start of the surgical procedure

• Gathers supplies for the surgical procedure and opens sterile supplies for the scrub nurse/technician

• Counts sponges, sharps, and instruments with scrub nurse technician before incision is made, at the beginning of wound closure, and at the end of the surgical procedure

• Ensures that all liquids and/or medications on the sterile field are labeled with a sterile marking pen when the liquid or medication is out of the original container or package

• Sends for the patient at the appropriate time

• Conducts preoperative patient assessment

• Safely assists patient to operating table and positions patient according to surgeon preference

• Participates in "time out" procedure with other surgical team members

• Apples conductive pad to patient if electrocautery used

• Assists anesthesia personnel during induction and extubation

• Continuously monitors procedure for any breaks in aseptic technique and anticipates needs of the team

• Handles surgical specimens per agency policy

• Documents on perioperative nurses' notes

• Communicates to family and PACU personnel during the surgical procedure

Role of a Scrub Nurse

• Helps circulating nurse prepare OR, open supplies

• Performs surgical hand antisepsis and dons sterile gown and gloves

• Prepares sterile field with procedure-appropriate supplies and instruments

• Participates in "time out" procedure with other surgical team members

• Performs sponge, sharps, and instrument counts with circulating nurse before incision is made, at the beginning of wound closure, and at the end of the surgical procedure

• Labels all liquids and/or medications on the sterile field with a sterile marking pen when the liquid or medication is out