ANAPHY
Anatomy (ah-nat′o-me)
• Greek words meaning to cut (tomy) apart (ana)
• - is the study of the structure and shape of the body and its parts and their relationships to one another.
Gross anatomy
• Is used whenever we look at our own body or study large body structures.
Microscopic anatomy
• is the study of body structures that are too small to be seen with the naked eye. The cells and tissues of the body can only be seen through a microscope.
Physiology (fiz″e-ol′o-je)
physio = nature; ology = the study of -> - is the study of how the body and its parts work or function
Organ System Overview
Integumentary (in-teg″u-men′tar-e) system
· It is the external covering of the body, or the skin, including the hair and fingernails.
· It waterproofs the body and cushions and protects the deeper tissues from injury.
· With the help of sunlight, it produces vitamin D.
· It also excretes salts in perspiration and helps regulate body temperature.
· Sensory receptors located in the skin alert us to what is happening at the body surface.
Skeletal system
· The skeletal system consists of bones, cartilages, and joints
· It supports the body and provides a framework that the skeletal muscles use to cause movement.
· It also has protective functions (for example, the skull encloses and protects the brain), and the cavities of the skeleton are the sites where blood cells are formed.
· The hard substance of bones acts as a storehouse for minerals.
Muscular System
· The muscles of the body have only one function— to contract or shorten. When this happens, movement occurs.
· The mobility of the body as a whole reflects the activity of skeletal muscles, the large, fleshy muscles attached to bones.
· The skeletal muscles form the muscular system. These muscles are distinct from the muscles of the heart and of other hollow organs, which move fluids (such as blood or urine) or other substances (such as food) along definite pathways within the body.
Nervous System
· It is the body’s fast-acting control system.
· It consists of the brain, spinal cord, nerves, and sensory receptors.
· The body must be able to respond to stimuli coming from outside the body (such as light, sound, or changes in temperature) and from inside the body (such as decreases in oxygen or stretching of tissue).
Endocrine System
· Like the nervous system, the endocrine (en′do-krin) system controls body activities, but it acts much more slowly.
· Endocrine glands produce chemical molecules called hormones and release them into the blood to travel to relatively distant target organs.
· The endocrine glands include the pituitary, thyroid, parathyroids, adrenals, thymus, pancreas, pineal, ovaries (in the female), and testes (in the male).
Cardiovascular System
· The primary organs of the cardiovascular system are the heart and blood vessels.
· Using blood as a carrier, the cardiovascular system delivers oxygen, nutrients, hormones, and other substances to, and picks up wastes such as carbon dioxide from, cells near sites of exchange.
· White blood cells and chemicals in the blood help to protect the body from such foreign invaders as bacteria, viruses, and tumor cells.
· The heart propels blood out of its chambers into blood vessels to be transported to all body tissues.
Lymphatic System
· The role of the lymphatic system complements that of the cardiovascular system.
· Its organs include lymphatic vessels, lymph nodes, and other lymphoid organs such as the spleen and tonsils.
· When fluid leaks into tissues from the blood, lymphatic vessels return it to the bloodstream so that there is enough blood to continuously circulate through the body.
· The lymph nodes and other lymphoid organs help to cleanse the blood and house white blood cells involved in immunity.
Respiratory System
· The job of the respiratory system is to keep the body supplied with oxygen and to remove carbon dioxide.
· The respiratory system consists of the nasal passages, pharynx, larynx, trachea, bronchi, and lungs.
Digestive System
· The digestive system is basically a tube running through the body from mouth to anus.
· The organs of the digestive system include the oral cavity (mouth), esophagus, stomach, small and large intestines, and rectum plus a number of accessory organs (liver, salivary glands, pancreas, and others).
· Their role is to break down food and deliver the resulting nutrients to the blood for dispersal to body cells.
· The pancreas, which delivers digestive enzymes to the small intestine, has both endocrine and digestive functions.
Urinary System
· The urinary system removes the nitrogen-containing wastes from the blood and flushes them from the body in urine.
· This system, often called the excretory system, is composed of the kidneys, ureters, bladder, and urethra
· Other important functions of this system include maintaining the body’s water and salt (electrolyte) balance, regulating the acid-base balance of the blood, and helping to regulate normal blood pressure.
Reproductive System
· The role of the reproductive system is to produce offspring.
· The male testes produce sperm. Other male reproductive system structures are the scrotum, penis, accessory glands, and the duct system, which carries sperm to the outside of the body.
· The female ovaries produce eggs, or ova; the female duct system consists of the uterine tubes, uterus, and vagina.
· The uterus provides the site for the development of the fetus.
Levels of Structural Organization
Chemical level – atoms combine to form molecules.
Cellular level – cells are made up of molecules.
Tissue level – it is consisting of similar type of cells.
Organ level – it is made up of different type of tissues.
Organ System level – are consist of different organs that work closely together.
Organismal level - a human being is made up of an organ system.
At which level of structural organization is the stomach? At which level is a glucose molecule?
Which organ system includes the trachea, lungs, nasal cavity, and bronchi?
Which system functions to remove waste and help regulate blood pressure?
Necessary Life Functions
• Maintaining Boundaries
• Movement
• Responsiveness
• Digestion
• Metabolism
• Excretion
• Reproduction
• Growth
Survival Needs
• Nutrients
• Oxygen
• Atmospheric pressure
• Normal body temperature
In addition to being able to metabolize, grow, digest food, and excrete waste, what other functions must an organism perform if it is to survive?
Oxygen is a survival need. Why is it so important? In which life function does oxygen participate directly?
Anatomical position - The body is erect with the feet parallel and the arms hanging at the sides with the palms facing forward.
Directional Terms
Body Parts and Regions
Subdivisions of the Abdomen
Planes of Section of the Body
Planes of Section Through an Organ
Trunk Cavities
Other Body Cavities
• Oral cavity and digestive cavity.
• Nasal cavity
• Orbital cavities
• Middle ear cavities
Serous Membranes - The cavity, or space, between the visceral and parietal serous membranes is normally filled with a thin, lubricating film of serous fluid produced by the membranes. As an organ rubs against another organ or against the body wall, the serous fluid and smooth serous membranes reduce friction.
What is the Anatomical position, and why is it important that an anatomy student understands it?
The axilla and the acromial areas are both in the general area of the shoulder. To what specific body area does each of these terms apply?
Use anatomical language to describe the location of a cut to the back of your left forearm.
Homeostasis (hō′mē-ō-stā′sis; homeo-, the same; -stasis, to stop) - is the existence and maintenance of a relatively constant environment within the body despite fluctuations in either the external environment or the internal environment.
Homeostatic mechanisms - normally maintain body temperature near an average normal value or set point. Most homeostatic mechanisms are governed by the nervous system or the endocrine system.
Negative Feedback Mechanism - Negative feedback is when any deviation from the set point is made smaller or is resisted. Negative feedback does not prevent variation but maintains variation within a normal range.
3 Components
• Receptor
• Control center
• Effector
Positive Feedback Mechanism - occur when the initial stimulus further stimulates the response. Positive means that the deviation from the set point becomes even greater. In this case, the word “positive” indicates an increase. At times, this type of response is required to re-achieve homeostasis.
CRITICAL THINKING
1. A man who was victim of a gunshot wound has lost blood. His blood pressure is low and decreasing, and his heart rate is increased despite the fact that the bleeding has stopped. He receives a blood transfusion, which results in an increase in blood pressure and a reduction in heart rate. Give these changes a physiological rationale.
2. Where and in what quadrant and area would a person feel pain if they had a urinary bladder infection?
3. A male victim had a bullet enter his left side, travel through his left lung, and strike his heart. List the cavities and serous membranes that the bullet passes through in chronological order.
Anatomy and Physiology
Module 2 – Basic Chemistry
Chemistry - is the scientific discipline concerned with the atomic composition and structure of substances and the reactions they undergo. It is the basis for how the body transforms and uses energy and for how our cells use crucial molecules such as carbohydrates, lipids, proteins, and nucleic acids.
Chemistry helps us understand the interactions of different molecules and why some interactions store energy, such as in fat, and other interactions release energy, such as when enzymes break down our food.
Everything that happens in the body, from cells responding to their surroundings to breaking down the food we eat, requires the movement of chemicals such as ions, carbohydrates, and lipids as they participate in chemical reactions.
Matter - All living and nonliving things are composed of matter, which is anything that occupies space and has mass. Mass is the amount of matter in an object, and weight is the gravitational force acting on an object of a given mass.
· Exists in solid, liquid, and gaseous states, all of which are found in the human body.
· May be changed both physically and chemically. Physical changes do not alter the basic nature of a substance. Chemical changes do alter the composition of the substance—often substantially.
Energy: - has no mass and does not take up space.
· Can be measured only by its effects on matter.
· The ability to do work or to put matter into motion.
According to the law of conservation of energy, the total energy of the universe is constant. Therefore, energy is neither created nor destroyed.
2 Types:
1. Kinetic (k˘ıneh′tik) energy - displayed in the constant movement of the tiniest particles of matter (atoms) as well as in larger objects.
2. Potential energy - inactive or stored energy.
Forms of Energy:
· Chemical energy - is stored in the bonds of chemical substances. When the bonds are broken, the (potential) stored energy is unleashed and becomes kinetic energy (energy in action).
· Electrical energy - results from the movement of charged particles. In your house, electrical energy is the flow of subatomic particles called electrons along the wiring.
· Mechanical energy - is energy directly involved in moving matter. When you pedal a bicycle, your legs provide the mechanical energy that turns the wheels.
· Radiant energy - it is the energy of the electromagnetic spectrum that travels in waves.
Energy Conversions
Inside the body, chemical energy from food is trapped in the bonds of a high-energy chemical called ATP (adenosine triphosphate).
Composition of Matter
All matter is composed of a limited number of substances called elements, unique substances that cannot be broken down into simpler substances by ordinary chemical methods. Examples of elements include many commonly known substances, such as oxygen, silver, gold, copper, and iron.
Elements - unique substances that cannot be broken down into simpler substances by ordinary chemical methods. Each element is composed of very similar particles, or building blocks, called atoms. Because all elements are unique, the atoms of each element differ from those of all other elements.
Atomic symbol - the atomic symbol is simply the first or first two letters of the element’s name. For example, C stands for carbon, O for oxygen, and Ca for calcium.
Atom - comes from the Greek word meaning “incapable of being divided”. According to this notion, you could theoretically divide a pure element, such as a block of gold, into smaller and smaller particles until you got down to the individual atoms, at which point you could subdivide no further.
Subatomic particles - Clusters of even smaller components of atom.
· Protons (p+) - have a positive charge
· neutrons (n0) - uncharged, or neutral.
· electrons (e−) - bear a negative charge equal in strength to the positive charge of the protons.
The planetary model of an atom portrays the atom as a miniature solar system in which the protons and neutrons are clustered at the center of the atom in the atomic nucleus.
The orbital model depicts the general location of electrons outside the nucleus as a haze of negative charge referred to as the electron cloud.
Atomic Number - is equal to the number of protons its atoms contain. Atoms of each element contain a different number of protons from the atoms of any other element; hence, its atomic number is unique. Because the number of protons is always equal to the number of electrons, the atomic number indirectly also tells us the number of electrons that atom contains.
Atomic Mass Number - is the sum of the masses of all the protons and neutrons contained in its nucleus.
Atomic Weight and Isotopes - it seems that the atomic weight of an atom should be equal to its atomic mass. This would be so if there were only one type of atom representing each element.
Isotopes have the same number of protons and electrons but vary in the number of neutrons they contain. Thus, the isotopes of an element have the same atomic number but different atomic masses. Because all of an element’s isotopes have the same number of electrons (and electrons determine bonding properties), their chemical properties are exactly the same.
Common Elements Making Up the Human Body
The Chemical Composition of Living Matter
2 major classes:
Organic Compounds
Most organic compounds are very large molecules, but their interactions with other molecules typically involve only small, reactive parts of their structure called functional groups (acid groups, amines, and others).
Polymers - are chainlike molecules made of many similar or repeating units – monomers – joined together by dehydration synthesis.
· During dehydration synthesis removal of a water molecule (dehydration) at the bond site occurs each time a monomer is added to the growing polymer chain.
· When polymers must be broken down or digested to their monomers, the reverse process, called hydrolysis, occurs.
Carbohydrates - means “hydrated carbon.” It include sugars and starches, contains carbon, hydrogen, and oxygen.
1. Monosaccharides - means one (mono) sugar (saccharide), and thus monosaccharides are also referred to as simple sugars.
- The most important monosaccharides in the body are glucose, fructose, galactose, ribose, and deoxyribose. Glucose, also called blood sugar, is the universal cellular fuel. Fructose and galactose are converted to glucose for use by body cells. Ribose and deoxyribose form part of the structure of nucleic acids, another group of organic molecules responsible for genetic information.
2. Disaccharides - or double sugars
- It is formed when two simple sugars are joined by dehydration synthesis. > Happens when a hydrogen atom is removed from one monomer and a hydroxyl group (OH) is removed from the monomer it is to be joined with.
- Some of the important disaccharides in the diet are sucrose (glucose-fructose), which is cane sugar; lactose (glucose-galactose), found in milk; and maltose (glucose-glucose), or malt sugar.
3. Polysaccharides - Long, branching chains of linked simple sugars.
- Because they are large, insoluble molecules, they are ideal storage products.
- they lack the sweetness of simple and double sugars.
· Starch is the storage polysaccharide formed by plants. We invest it in the form of “starchy” foods, such as grain products (corn, rice) and root vegetables (potatoes and carrots, for example).
· Glycogen is a slightly smaller, but similar, polysaccharide found in animal tissues (largely in the muscles and the liver). Like starch, it is a polymer of linked glucose units.
2. Lipids - or fats. They are a large and diverse group of organic compounds.
- They enter the body in the form of meats, egg yolks, dairy products, and oils. The most abundant lipids in the body are triglycerides, phospholipids, and steroids.
- Lipids are insoluble in water but readily dissolve in other lipids and in organic solvents such as alcohol and acetone.
3. Triglycerides - neutral fats. are composed of two types of building blocks, fatty acids and glycerol.
- Fatty acid chains with only single covalent bonds between carbon atoms are referred to as saturated fats.
- Fatty acids that contain one or more double bonds between carbon atoms are said to be unsaturated fats (monounsaturated and polyunsaturated, respectively).
- Triglycerides represent the body’s most abundant and concentrated source of usable energy. When they are oxidized, they yield large amounts of energy.
- They are stored chiefly in fat deposits beneath the skin and around body organs, where they help insulate the body and protect deeper body tissues from heat loss and injury.
4. Trans fats, common in many margarines and baked products, are oils that have been solidified by the addition of hydrogen atoms at sites of double carbon bonds, which reduces those bonds to single carbon bonds.
- They increase the risk of heart disease by raising “bad” cholesterol and decreasing “good” cholesterol.
5. The omega-3 fatty acids, found naturally in cold-water fish, appear to decrease the risk of heart disease and some inflammatory diseases.
6. Phospholipids - It is similar to triglycerides; the major difference is that a phosphorus-containing group is always part of the molecule and takes the place of one of the fatty acid chains.
7. Steroids - like fats, steroids are made largely of hydrogen and carbon atoms and are fat-soluble.
- The single most important steroid molecule is cholesterol. We ingest cholesterol in animal products such as meat, eggs, and cheese, and some is made by the liver, regardless of dietary intake.
- Cholesterol is found in cell membranes and is the raw material used to make vitamin D, steroid hormones (chemical signaling molecules in the body), and bile salts (which help break down fats during digestion).
Proteins - account for over 50 percent of the organic matter in the body, and they have the most varied functions of all organic molecules.
- The building blocks of proteins are small molecules called amino (ah-me′no) acids.
- Strands like fibrous proteins (structural proteins), also called structural proteins, appear most often in body structures. They are very important in binding structures together and providing strength in certain body tissues.
- Globular proteins are water-soluble proteins that play crucial roles in virtually all biological processes. Because they do things rather than just form structures, they are also called functional proteins; the scope of their activities is remarkable.
Enzymes - Are functional proteins that act as biological catalysts. They regulate essentially every chemical reaction that goes on within the body.
‐ A catalyst is a substance that increases the rate of a chemical reaction without becoming part of the product or being changed itself.
‐ Enzymes are capable of catalyzing millions of reactions each minute.
Representative Class of Functional Proteins
What is the primary structure of proteins?
Which is more important for building body structures, fibrous or globular proteins?
Inorganic Compounds
Water - It is the most abundant inorganic compound in the body. It accounts for about two-thirds of body weight.
· High heat capacity - it absorbs and releases large amounts of heat before its temperature changes.
· Polarity/solvent properties. - It is an excellent solvent because of its polarity; indeed, it is often called the “universal solvent.”
· Chemical reactivity. - Water is an important reactant in some types of chemical reactions.
· Cushioning. - Water also serves a protective function.
Salts - It is an ionic compound containing cations other than the hydrogen ion (H+) and anions other than the hydroxide ion (OH−).
Acids and Bases - Like salts, acids and bases are electrolytes. That is, they ionize, dissociate in water, and can then conduct an electrical current.
An acid is a proton donor. Because a hydrogen atom without its electron is a proton, any substance that releases hydrogen ions (H+) in water is an acid. For example, hydrochloric acid (HCl) in the stomach forms H+ and chloride ions (Cl−): HCl → H+ + Cl−
Characteristics of Acids
· It has a sour taste and can dissolve many metals or cause “burns”.
· It is a substance that can release hydrogen ions (H+) in detectable amounts.
· As free protons, hydrogen ions can influence the acidity of body fluids.
A base is a proton acceptor. For example, sodium hydroxide (NaOH) forms sodium ions (Na+) and hydroxide ions (OH−). It is a base because the OH− is a proton acceptor that binds with a H+ to form water.
Characteristics of Bases
· It has a bitter taste, feel slippery, and are proton (H+) acceptors.
· When protons are bound to a molecule, they are unable to affect the acidity of body fluids.
· The hydroxide ion is an avid proton (H+) seeker, and any base containing this ion is considered a strong base. By contrast, bicarbonate ion (HCO3), an important base in blood, is a fairly weak base.
pH: Acid-Base Concentrations
· The relative concentration of hydrogen (and hydroxide) ions in various body fluids is measured in concentration units called pH (pe-ˉach) units.
· The pH scale, which was devised in 1909 by a Danish biochemist (and part-time beer brewer) named Sorensen, is based on the number of protons in solution.
· The pH scale runs from 0 to 14 and each successive change of 1 pH unit represents a tenfold change in hydrogen ion concentration.
· At a pH of 7, the number of hydrogen ions exactly equals the number of hydroxide ions, and the solution is neutral; that is, neither acidic nor basic.
What property of water prevents rapid changes in body temperature?
Is a pH of 11 acidic or basic? What is the difference in pH between a solution at pH 11 and a solution at pH 5?
Salts are electrolytes. What does that mean?
Which is a proton donor—an acid or a base?
Nucleic acid
They make up the genes which provide the basic blueprint of life.
2 Major kinds:
1. Deoxyribonucleic Acid - is the genetic material found within the cell nucleus (the control center of the cell).
2 fundamental roles:
· It replicates itself exactly before a cell can divide, thus ensuring that every body cell gets an identical copy of the genetic information
· It provides the instructions for building every protein in the body.
2. Ribonucleic acid (RNA) - functions outside the nucleus and can be considered the “molecular assistant” of DNA; that is, RNA carries out the orders for protein synthesis issued by DNA.
3 major varieties
· Messenger RNA (mRNA) - carries the information for building the protein from the DNA to the ribosomes, the protein-synthesizing sites.
· Transfer RNA (tRNA) - ferries amino acids to the ribosomes.
· Ribosomal RNA (rRNA) - forms part of the ribosomes, where it oversees the translation of the message and the binding together of amino acids to form the proteins.
Adenosine triphosphate (ă-den′ō-sēn trī-fos′fāt) (ATP) is an especially important organic molecule found in all living organisms. It consists of adenosine (the sugar ribose with the organic base adenine) and three phosphate groups. Adenosine diphosphate (ADP) has only two phosphate groups. The potential energy stored in the covalent bond between the second and third phosphate groups is important to living organisms because it provides the energy used in nearly all of the chemical reactions within cells.
Anatomy and Physiology
Module 3 – Cells and Tissues
CELLS - Are the structural units of all living things, from one-celled organisms such as amoebas to complex multicellular organisms such as humans, animals, and plants.
4 concepts of the cell theory:
· A cell is the basic structural and functional unit of living organisms.
· The activity of an organism depends on the collective activities of its cells.
· According to the principle of complementarity, the activities of cells are dictated by their structure (anatomy), which determines function (physiology).
· Continuity of life has a cellular basis.
3 main regions or parts—a nucleus (nu′kle-us), a plasma membrane, and the cytoplasm (si′to-plazm″).
The Nucleus - (nucle = kernel) - It is the “headquarters,” or the control center of all cells.
3 recognizable structures:
· Nuclear envelope - the nuclear envelope allows some but not all substances to pass through it, but substances pass through it much more freely than elsewhere because of its relatively large pores. Nuclear membrane - encloses a jellylike fluid called nucleoplasm (nu′kle-o-plazm″) in which other nuclear elements are suspended.
· Nucleoli - The nucleus contains one or more small, dark staining, essentially round bodies called nucleoli (nu-kle′o-li; “little nuclei”).
· Chromatin - It is formed when a cell is not dividing, its DNA is carefully wound around proteins called histones to form a loose network of “beads on a string”.
The Plasma Membrane - It is a fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment. Its unique structure allows it to play a dynamic role in many cellular activities. The structure of the plasma membrane consists of two phospholipid (fat) layers arranged “tail to tail,” with cholesterol and floating proteins scattered among them.
The Fluid Mosaic Model - The proteins, some of which are free to move and bob in the lipid layer, form a constantly changing pattern or mosaic, hence the name of the model that describes the plasma membrane.
Cells are bound together in three ways:
· Glycoproteins in the glycocalyx act as an adhesive or cellular glue.
· Wavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion.
· Special cell membrane junctions are formed. These junctions vary structurally depending on their roles.
Types of Cell Junctions:
· Tight junctions - are impermeable junctions that encircle the cells and bind them together into leakproof sheets.
· Desmosomes - Are anchoring junctions scattered like rivets along the sides of adjacent cells.
· Gap Junctions - communicating junctions. These junctions are commonly found in the heart and between embryonic cells.
The Cytoplasm - is the cellular material outside the nucleus and inside the plasma membrane. ^It is the site of most cellular activities, it is the “factory floor” of the cell.
Three Major Components:
· The Cytoplasm - is the cellular material outside the nucleus and inside the plasma membrane. It is the site of most cellular activities, it is the “factory floor” of the cell.
· Cytosol - Is semitransparent fluid that suspends the other elements. Dissolved in the cytosol, which is largely water, are nutrients and a variety of other solutes (sol′yuˉ tz; dissolved substances).
· Inclusion - Chemical substances that may or may not be present, depending on the specific cell type. Most inclusions are stored nutrients or cell products floating in the cytosol. It acts as a cellular “storage” where items are kept on hand until needed.
· Organelles – (or″gah-nelz′) “little organs”. Each type of organelle is specialized to carry out a specific function for the cell as a whole, much like the organs carry out specialized functions for the whole body.
The Cellular Factory:
Mitochondria - (mi″to-kon′dre-ah; singular: mitochondrion). They are the “powerhouses” of the cell because it supplies most of the ATP. Cells, such as liver and muscle cells, use huge amounts of ATP and have hundreds of mitochondria.
Ribosomes - Are tiny, bilobed, dark bodies made of proteins and one variety of RNA called ribosomal RNA. Ribosomes are the actual sites of protein synthesis in the cell.
Endoplasmic Reticulum - Is a system of fluid-filled tunnels (or canals) that coil and twist through the cytoplasm. It is continuous with the nuclear envelope and accounts for about half of a cell’s membranes. It serves as a mini circulatory system for the cell because it provides a network of channels for carrying substances (primarily proteins) from one part of the cell to another.
2 Forms:
· Rough endoplasmic reticulum - All building materials of cellular membranes are formed either in it or on it. It is especially abundant in cells that make (synthesize) and export (secrete) proteins.
· Smooth endoplasmic reticulum - It communicates with the rough ER, but it plays no role in protein synthesis, because it lacks ribosomes. ^Instead, it functions in lipid metabolism (cholesterol and fat synthesis and breakdown) and detoxification of drugs and pesticides.
Golgi Apparatus - It appears as a stack of flattened membranous sacs that are associated with swarms of tiny vesicles. It is generally found close to the ER and is the principal “traffic director” for cellular proteins. Its major function is to modify, package, and ship proteins (sent to it by the rough ER via transport vesicles) in specific ways, depending on their final destination. Initially, all proteins leaving the Golgi apparatus accumulate in sacs called Golgi vesicles.
Lysosomes - Are membranous “bags” containing powerful digestive enzymes. It functions as cellular “stomachs.” Lysosomes are especially abundant in white blood cells called phagocytes, the cells that dispose of bacteria and cell debris.
Peroxisomes - Are membranous sacs containing powerful oxidase (ok′s˘ı-dˉaz) enzymes that use molecular oxygen (O2) to detoxify a number of harmful or poisonous substances, including alcohol and formaldehyde. Their most important function is to “disarm” dangerous free radicals. Peroxisomes are especially numerous in liver and kidney cells, which are very active in detoxification.
Centrioles - Are best known for their role in generating microtubules and also, for directing the formation of the mitotic spindle during cell division.
Cytoskeleton - An elaborate network of protein structures extends throughout the cytoplasm. It acts as a cell’s “bones and muscles” by furnishing an internal framework that determines cell shape, supports other organelles, and provides the machinery for intracellular transport and various types of cellular movements.
Cell Extensions
Cilia - Are whiplike cellular extensions that move substances along the cell surface.
Flagella - The projections formed by the centrioles are substantially longer. The only example of a flagellated cell in the human body is the sperm, which has a single propulsive flagellum called its tail.
Cell Types, Shapes, Structures, and Functions
· Cells that connect body parts
o Fibroblast - This cell has an elongated shape, like the cable-like fibers that it secretes. It has an abundant rough ER and a large Golgi apparatus to make and secrete the protein building blocks of these fibers.
o Erythrocyte (red blood cell) - This cell carries oxygen in the blood. Its biconcave disc shape provides extra surface area for the uptake of oxygen and streamlines the cell, so it flows easily through the bloodstream.
· Cells that cover and line the body organs
o Epithelial cells - The hexagonal shape of this cell is exactly like a “cell” in a honeycomb of a beehive. This shape allows epithelial cells to pack together in sheets.
· Cells that move organs and body parts
o Skeletal, cardiac, and smooth muscle cells - These cells are elongated and filled with abundant contractile filaments, so they can shorten forcefully and move the bones, pump blood, or change the size of internal organs to move substances around the body.
· Cells that stores nutrient
o Fat cells - The huge spherical shape of a fat cell is produced by a large lipid droplet in its cytoplasm.
· Cells that fight diseases
o White blood cells/macrophage - This cell extends long pseudopods (“false feet”) to crawl through tissue to reach infection sites. The many lysosomes within the cell digest the infectious microorganisms (such as bacteria) that it “eats.”
· Cells that gather information and controls body functions.
o Nerve cell (neuron) - This cell has long processes (extensions) for receiving messages and transmitting them to other structures in the body. The processes are covered with an extensive plasma membrane, and a plentiful rough ER synthesizes membrane components and signaling molecules called neurotransmitters.
· Cells of Reproduction
o Oocyte (female) - The largest cell in the body, this egg cell contains several copies of all organelles, for distribution to the daughter cells that arise when the fertilized egg divides to become an embryo.
o Sperm (male) - This cell is long and streamlined, built for swimming to the egg for fertilization. Its flagellum acts as a motile whip to propel the sperm.
Cell Physiology
Most cells have the ability to metabolize (use nutrients to build new cell material, break down substances, and make ATP), digest foods, dispose of wastes, reproduce, grow, move, and respond to a stimulus (irritability).
Membrane Transport
The plasma membrane is a selectively permeable barrier. Selective permeability means that a barrier allows some substances to pass through it while excluding others. Thus, it allows nutrients to enter the cell but keeps many undesirable or unnecessary substances out.
The fluid environment on both sides of the plasma membrane is an example of a solution. Components or substances present in smaller amounts are called solutes. The solutes in a solution are so tiny that the molecules cannot be seen with the naked eye and do not settle out.
· Intracellular fluid - (collectively, the nucleoplasm and the cytosol) is a solution containing small amounts of gases (oxygen and carbon dioxide), nutrients, and salts, dissolved in water.
· Extracellular fluid - or interstitial fluid, the fluid that continuously bathes the exterior of our cells.
3 types of solutions
Isotonic (i″so-ton′ik - “same tonicity”) solutions (such as 5 percent glucose and 0.9 percent saline) have the same solute and water concentrations as cells do. Isotonic solutions cause no visible changes in cells, and when such solutions are infused into the bloodstream, red blood cells (RBCs) retain their normal size and disclike shape.
These fluids are useful when the patient has lost fluid volume from blood loss, trauma, or dehydration due to excessive nausea/vomiting or diarrhea. When administering isotonic solutions, continue monitoring the patient to ensure the rehydration does not turn into fluid overload.
If red blood cells are exposed to a hypertonic (hi″per-ton′ik) solution—a solution that contains more solutes, or dissolved substances, than there are inside the cells—the cells begin to shrink. This is because water is in higher concentration inside the cell than outside, so it travels down its concentration gradient and leaves the cell.
Hypertonic solutions are sometimes given to patients who have edema (swelling of the feet and hands due to fluid retention). Such solutions draw water out of the tissue spaces into the bloodstream so that the kidneys can eliminate excess fluid.
When a solution contains fewer solutes (and therefore more water) than the cell does, it is hypotonic (hi″po-ton′ik) to the cell. Cells placed in hypotonic solutions plump up rapidly as water rushes into them. Distilled water represents the most extreme example of a hypotonic fluid. Because it contains no solutes at all, water will enter cells until they finally burst, or lyse (rupture).
Hypotonic solutions are sometimes infused intravenously (slowly and with care) to rehydrate extremely dehydrated patients. In less extreme cases, drinking hypotonic fluids usually does the trick.
Diffusion - is the process by which molecules (and ions) move away from areas where they are more concentrated (more numerous) to areas where they are less concentrated (with fewer of them).
Filtration - is the process by which water and solutes are forced through a membrane (or capillary wall) by fluid, or hydrostatic, pressure.
In the kidneys, water and small solutes filter out of the capillaries into the kidney tubules because the blood pressure in the capillaries is greater than the fluid pressure in the tubules. Part of the filtrate formed in this way eventually becomes urine.
Osmosis - Osmosis into and out of cells is occurring all the time as water moves down its concentration gradient. The movement of water across the membrane occurs quickly. Anyone administering an IV (intravenous, into the vein) solution must use the correct solution to protect the patient’s cells from life-threatening dehydration or rupture.
2 most important active processes:
· Passive Processes, substances are transported across the membrane without any energy input from the cell.
· Active Processes, the cell provides the metabolic energy (ATP) that drives the transport process.
Active transport - It require protein carriers that interact specifically and reversibly with the substances to be transported across the membrane.
The sodium-potassium (Na+-K+) pump alternately carries sodium ions (Na+) out of and potassium ions (K+) into the cell. It uses ATP to energize its protein carriers, which are called solute pumps.
Vesicular transport - It involves help from ATP to fuse or separate membrane vesicles and the cell membrane, moves substances into or out of cells “in bulk” without their actually crossing the plasma membrane directly.
· Exocytosis - (ek″so-si-to′sis; “out of the cell”). is the mechanism that cells use to actively secrete hormones, mucus, and other cell products or to eject certain cellular wastes.
· Endocytosis - (en″do-si-to′sis; “into the cell”). Includes those ATP-requiring processes that take up, or engulf, extracellular substances by enclosing them in a vehicle.
Cell Division - The function of cell division is to produce more cells for growth and repair processes.
Mitosis - is the process of dividing a nucleus into two daughter nuclei with exactly the same genes as the “mother” nucleus.
1. Interphase - in which the cell grows and carries on its usual metabolic activities.
2. Prophase - The centrioles separate from each other and begin to move toward opposite sides of the cell, directing the assembly of a mitotic spindle (composed of microtubules) between them as they move.
3. Metaphase - In this short stage, the chromosomes line up at the metaphase plate (the center of the spindle midway between the centrioles) so that a straight line of chromosomes is seen.
4. Anaphase - During anaphase, the centromeres that have held the chromatids together split. This careful division of sister chromatids ensures that each daughter cell gets one copy of every chromosome.
5. Telophase - Telophase is essentially prophase in reverse. The chromosomes at opposite ends of the cell uncoil to become threadlike chromatin again. The spindle breaks down and disappears, a nuclear envelope forms around each chromatin mass, and nucleoli appear in each of the daughter nuclei.
6. Cytokinesis - the division of the cytoplasm, usually begins during late anaphase and completes during telophase.
Tissues - Groups of cells that are similar in structure and function.
4 primary tissue types: - epithelial (covering), Connective (support), nervous (control), and muscle tissues (movement).
Epithelial Tissue:
· Epithelial cells fit closely together to form continuous sheets.
· The membranes always have one free (unattached) surface or edge.
· The anchored (basal) surface of epithelium rests on a basement membrane, a structureless material secreted by both the epithelial cells and the connective tissue cells deep to the epithelium.
· Epithelial tissues have no blood supply of their own (that is, they are avascular) and depend on diffusion from the capillaries in the underlying connective tissue for food and oxygen.
· If well nourished, epithelial cells regenerate easily.
Classification of Epithelia:
1. Simple Epithelia - The simple epithelia are most concerned with absorption, secretion, and filtration. Because simple epithelia are usually very thin, protection is not one of their specialties.
· Simple Squamous epithelium - This type of epithelium usually forms membranes where filtration or exchange of substances by rapid diffusion occurs. (i.e., air sacs of the lungs (called alveoli), walls of capillaries, and the interstitial fluid.
· Simple Cuboidal epithelium - common in glands and their associated small tubes called ducts (i.e., the salivary glands, pancreas, walls of the kidney tubules, and covers the surface of the ovaries.).
2. Simple Columnar epithelium - is made up of a single layer of tall cells that fit closely together. Goblet cells [intestinal mucosal epithelial cells that serve as the primary site for nutrient digestion and mucosal absorption], which produce a lubricating mucus.
3. Stratified Epithelia - Stratified epithelia consist of two or more cell layers. Being considerably more durable than the simple epithelia, these epithelia function primarily in protection.
· Stratified Squamous epithelium - is the most common stratified epithelium in the body. It usually consists of many cell layers.
· Stratified Cuboidal and Stratified Columnar epithelium - Both of these epithelia are fairly rare in the body, found mainly in the ducts of large glands.
· Transitional epithelium - is a highly modified, stratified squamous epithelium that forms the lining of only a few organs—the urinary bladder, the ureters, and part of the urethra.
· Pseudostratified Columnar epithelium - All of its cells rest on a basement membrane but some of its cells are shorter than others, and their nuclei appear at different heights above the basement membrane.
Glandular epithelium - A gland consists of one or more cells that make and secrete a particular product. A secretion typically contains protein molecules in an aqueous (water-based) fluid.
· Endocrine - often called ductless glands. Their secretions (all hormones) diffuse directly into the blood vessels that weave through the glands. Examples of endocrine glands include the thyroid, adrenals, and pituitary.
· Exocrine - retain their ducts, and their secretions exit through the ducts to the epithelial surface. Exocrine glands, which include the sweat and oil glands, liver, and pancreas, are both internal and external.
Connective Tissue - Connective tissues perform many functions, but they are primarily involved in protecting, supporting, and binding together other body tissues.
· Bone - sometimes called osseous (os′e-us) tissue, is composed of osteocytes (os′te-o-sıˉtz; bone cells) sitting in cavities called lacunae (lah-ku′ne; “pits”).
· Cartilage - Most widespread is hyaline (hi′ah-lin) cartilage, which has abundant collagen fibers hidden by a rubbery matrix with a glassy (hyalin = glass), blue-white appearance. It forms the trachea, or windpipe, attaches the ribs to the breastbone, and covers bone ends at joints.
· Dense Connective tissue - Dense connective tissue forms strong, ropelike structures such as tendons and ligaments. Tendons attach skeletal muscles to bones; ligaments connect bones to bones at joints.
· Loose Connective tissue - Are softer and have more cells and fewer fibers than any other connective tissue type except blood.
· Adipose tissue also protects some organs individually—the kidneys are surrounded by a capsule of fat, and adipose tissue cushions the eyeballs in their sockets.
· Blood - or vascular tissue. Is considered a connective tissue because it consists of blood cells surrounded by a nonliving, fluid matrix called blood plasma.
Muscle Tissue - are highly specialized to contract, or shorten, which generates the force required to produce movement.
· Cardiac Muscles - is found only in the heart wall.
· Skeletal Muscles - tissue is packaged by connective tissue sheets into organs called skeletal muscles, which are attached to the skeleton.
· Smooth Muscles - Smooth muscle is found in the walls of hollow organs such as the stomach, uterus, and blood vessels.
Nervous Tissue – All neurons receive and conduct electrochemical impulses from one part of the body to another; thus, irritability and conductivity are their two major functional characteristics.
Tissue Repair (Wound Healing) - When tissue injury does occur, it stimulates the body’s inflammatory and immune responses, and the healing process begins almost immediately.
· Inflammation is a general (nonspecific) body response that attempts to prevent further injury.
· The immune response, in contrast, is extremely specific and mounts a vigorous attack against recognized invaders, including bacteria, viruses, and toxins.
Events of Tissue Repair
Anatomy and Physiology
Module 4 – Skin and Body Membranes
Skin and Body Membranes
Body membranes cover surfaces, line body cavities, and form protective (and often lubricating) sheets around organs.
2 major groups:
• Epithelial membranes
Cutaneous membrane - generally called the skin or integumentary system, is the outer covering that we all rely on for protection.
Mucus Membrane - this membrane type lines all body cavities that open to the exterior, such as those of the hollow organs of the respiratory, digestive, urinary, and reproductive tracts.
Serous Membrane - it lines body cavities that are closed to the exterior (except for the dorsal body cavity and joint cavities).
• Connective tissue membranes - represented by synovial membranes. These membranes line the fibrous capsules surrounding joints, where they provide a smooth surface and secrete a lubricating fluid.
Functions of the Integumentary System
- Protects deeper tissues from:
• Mechanical damage (bumps)
• Chemical damage (acids and bases)
• Microbe damage
• Ultraviolet (UV) radiation
• Thermal (heat or cold) damage
• Desiccation (drying out)
The Integumentary System (Skin) - keeps water and other precious molecules in the body.
Epidermis - Most cells of the epidermis are keratinocytes (keratin cells), which produce keratin, the fibrous protein that makes the epidermis a tough protective layer in a process called keratinization. Like all other epithelial tissues, the epidermis is avascular; that is, it has no blood supply of its own.
5 Layers of the epidermis (strata):
Stratum Granulosum - Cells become flatter and increasingly keratinized.
Stratum Corneum - The outermost layer consists of 20 to 30 cell layers thick, but it accounts for about three-quarters of the epidermal thickness.
Nerve Ending - The nerve endings sense pain, touch, pressure, and temperature.
Epidermal dendritic cell - important “sentries” that alert and activate immune system cells to a threat such as bacterial or viral invasion.
Dermis - The dermis is the “hide.” It is a strong, stretchy envelope that helps to bind the body together.
2 major regions:
Papillary Layer - Is the superficial dermal region. On the palms of the hands and soles of the feet, the papillae are arranged in definite patterns that form looped and whorled ridges on the epidermal surface that increase friction and enhance the gripping ability of the fingers and feet.
Reticular Layer - Is the deepest skin layer. ^It contains dense irregular connective tissue, as well as blood vessels, sweat and oil glands, and deep pressure receptors called lamellar corpuscles.
Cutaneous Sensory Receptors
Elastic fibers - give the skin its elasticity when we are young.
The dermis is abundantly supplied with blood vessels that play a role in maintaining body temperature homeostasis.
Skin Color - Three pigments contribute to skin color: melanin, carotene, and hemoglobin.
• Melanin (yellow, reddish brown, or black) - Skin exposure to sunlight stimulates melanocytes to produce more melanin pigment, resulting in tanning of the skin.
People who produce a lot of melanin have brown-toned skin, whereas people with less melanin are light skinned.
• Carotene - orange-yellow pigment plentiful in carrots and other orange, deep yellow or leafy green vegetables. In people who eat large amounts of carotene-rich foods, the skin tends to take on a yellow-orange cast.
• Hemoglobin - (pigment in red blood cells) In light-skinned people, the crimson color of oxygen-rich hemoglobin in the dermal blood supply flushes through the transparent cell layers above and gives the skin a rosy glow.
Cyanosis - When hemoglobin is poorly oxygenated, both the blood and the skin of light-skinned people appear blue.
Jaundice is a condition produced when excess amounts of bilirubin circulating in the blood stream dissolve in the subcutaneous fat (the layer of fat just beneath the skin), causing a yellowish appearance of the skin and the whites of the eyes.
Appendages of the Skin
Cutaneous Glands - The cutaneous glands are all exocrine glands that release their secretions to the skin surface via ducts.
2 groups:
• Sebaceous (oil) glands - are found all over the skin, except on the palms of the hands and the soles of the feet. Their ducts usually empty into a hair follicle, but some open directly onto the skin surface.
• Sweat glands - also called sudoriferous (su”do-rif’er-us; sudor = sweat) glands, are widely distributed in the skin.
2 types:
Eccrine (ek’rin) glands - produce sweat, a clear secretion that is primarily water plus some salts (sodium chloride), vitamin C, traces of metabolic wastes (ammonia, urea, uric acid), and lactic acid (a chemical that accumulates during vigorous muscle activity).
Apocrine glands - are largely confined to the axillary (armpit) and genital areas of the body.
Hair and hair follicles
Hair Follicles - (folli = bag) are actually compound structures. Hair serves a few minor protective functions, such as guarding the head against bumps, shielding the eyes (via eyelashes), and helping to keep foreign particles out of the respiratory tract (via nose hairs).
Burns – is caused by denatured proteins that cause damage and cell death to the affected area.
Causes:
• Intense heat
• UV radiation (sunburn)
• Electricity
• Certain chemicals (such as acids)
Life threatening problems:
• Dehydration and electrolyte imbalance
• Infection
Classification: Burns are classified according to their severity (depth):
• First-degree burns, only the superficial epidermis is damaged. Sunburn without blistering is a first-degree burn.
• Second-degree burns involve injury to the epidermis and the superficial part of the dermis. The skin is red, painful, and blistered.
• Third-degree burns destroy both the epidermis and the dermis and often extend into the subcutaneous tissue, reflecting their categorization as full thickness burns. Blisters are usually present, and the burned area appears blanched (gray - white) or blackened - charred. Because the nerve endings in the area are destroyed, the burned area is not painful.
• Fourth-degree burns are also full-thickness burns, but they extend into deeper tissues such as bone, muscle, or tendons. These burns appear dry and leathery, and they require surgery and grafting to cover exposed tissue.
•
Pressure Ulcers - consist of injury to the skin and/or underlying tissue, usually over a bony prominence, as a result of force alone or in combination with movement. Previously called decubitus ulcers, pressure sores, or bedsores.
Risk Factors
• Friction and shearing force
• Immobility
• inadequate nutrition
• Fecal and Urinary Incontinence
• Excessive Body Heat
• Diminished Sensation
• Decreased Mental Status
• Advanced Age
Loss of lean body mass
Generalized thinning of the epidermis
Decreased strength and elasticity of the skin due to changes in the collagen fibers of the dermis
Increased dryness due to a decrease in the amount of oil produced by the sebaceous glands.
Diminished pain perception due to a reduction in the number of cutaneous end organs responsible for the sensation of pressure and light touch
Diminished venous and arterial flow due to aging vascular walls.
• Chronic Medical Conditions
Common Pressure Sites
Common Pressure Sites
Norton’s Pressure Area Risk Assessment Form (Scoring System)
This tool can be used to identify patients at-risk for pressure ulcers. The five subscale scores of the Norton Scale are added together for a total score that ranges from 5-20. A lower Norton score indicates higher levels of risk for pressure ulcer development. Generally, a score of 14 or less indicates at-risk status.
Braden Scale for Predicting Pressure Sore Risk.
The scale consists of six subscales and the total scores range from 6-23. A lower Braden score indicates higher levels of risk for pressure ulcer development. Generally, a score of 18 or less indicates at-risk status.
How do the body locations of serous and mucous membranes differ?
A scalpel penetrates the left lung and enters the heart. Name the six serous membrane layers the blade passes through as it moves from the body surface into the heart.
Where would you find a synovial membrane?
Anatomy and Physiology
Module 5 – Skeletal System
Skeleton - comes from the Greek word meaning “dried-up body.” The bones of the skeleton are part of the skeletal system, which also includes joints, cartilages, and ligaments (fibrous cords that bind the bones together at joints).
Functions:
• Support
• Protection
• Allow movement
• Storage
• Blood Cell Formation
Classification of Bones:
Structure of Bones:
Bones are organs, so they contain not only osseous tissue but also other connective tissues: fibrous tissue, cartilage, adipose tissue, and blood.
2 types of bone tissue (osseus):
• Compact bone - is dense and looks smooth and homogeneous
• Spongy bone - has a spiky, open appearance like a sponge.
Bone Formation and Growth:
Ossification - Is the process of bone formation in which most bones develop using hyaline cartilage structures as their “models.” After an osteoblast becomes completely surrounded by bone matrix, it becomes a mature bone cell, or osteocyte.
Bone Re-modeling:
Bone remodeling is the removal of existing bone by osteoclasts and the deposition of new bone by osteoblasts and occurs in all bone. Remodeling is responsible for changes in bone shape, the adjustment of bone to stress, bone repair, and calcium ion regulation in the body fluids.
Bones are remodeled continually in response to changes in two factors:
1. The calcium ion level in the blood
2. The pull of gravity and muscles on the skeleton.
Bone Repair:
Axial Skeleton
Skull - All but one of the bones of the skull are joined together by sutures, which are interlocking, immovable joints. Only the mandible (jawbone) is attached to the rest of the skull by a freely movable joint.
2 Sets of bones:
• Cranium
• Facial bones
Sutures
Cranium - The boxlike cranium is composed of eight large flat bones. Except for two sets of paired bones (the parietal and temporal), they are all single bones.
Facial - Fourteen bones make up the face. Twelve are paired; only the mandible and vomer are single.
Paranasal Sinuses
Hyoid Bone - Though not really part of the skull, is closely related to the mandible and temporal bones. It is unique in that it is the only bone of the body that does not articulate (form a joint) with any other bone.
Features:
Cervical Vertebrae
Thoracic Cage - - The bony thorax is routinely called the thoracic cage because it forms a protective cage of slender bones and cartilages around the organs of the thoracic cavity (heart, lungs, and major blood vessels). The sternum, ribs, and thoracic vertebrae make up the bony thorax.
Appendicular Skeleton - The appendicular skeleton is composed of 126 bones of the limbs (appendages) and the pectoral and pelvic girdles.
Bones of the Shoulder Girdle - Each pectoral girdle, or shoulder girdle, consists of two bones—a clavicle and a scapula.
Scapulae - The scapulae are not directly attached to the axial skeleton; they are loosely held in place by trunk muscles.
The acromion connects with the clavicle laterally at the acromioclavicular joint.
Arm - The arm is formed by a single bone, the humerus (hu′mer-us), which is a typical long bone.
Forearm - Two bones, the radius and the ulna, form the skeleton of the forearm.
Hand - The skeleton of the hand consists of the carpals, the metacarpals, and the phalanges (fah-lan′jˉez). The eight carpal bones, arranged in two irregular rows of four bones each, form the part of the hand called the carpus, or the wrist.
Bones of the Pelvic Girdle - The pelvic girdle is formed by two coxal (kok′sal) bones, commonly called hip bones, and the sacrum. Together with the coccyx pelvic girdle, the pelvic girdle forms the pelvis.
Pelvic Girdle - Each hip bone is formed by the fusion of three bones: the ilium, ischium, and pubis. The ilium (il′e-um), which connects posteriorly with the sacrum at the sacroiliac (sak″roil′e-ac) joint, is a large, flaring bone that forms most of the hip bone. The ischium (is′ke-um) is the “sit-down bone,” so called because it forms the most inferior part of the coxal bone. The pubis (pu′bis) is the most anterior and inferior part of a coxal bone.
Comparison of the male and female pelvis
Bones of the Lower Limbs
Foot - The foot, composed of the tarsals, metatarsals, and phalanges.
Joints - Also called articulations, are the sites where two or more bones meet.
2 Functions:
• They hold the bones together securely.
• Give the rigid skeleton mobility.
2 Classifications:
• Functional classification
Synarthroses (sin″ar-thro′sˉez)
Amphiarthroses (am″fe-ar-thro′sˉez)
Diarthroses (di″ar-thro′sˉez)
• Structural classification
Fibrous Joints
Cartilaginous Joints - The bones are united by fibrous tissue. The best examples of this type of joint are the sutures of the skull.
2 Functions:
Synchondroses
Symphyses
Synovial Joints
4 Distinguishing features:
Types of Synovial Joints Based on Shape
Anatomy and Physiology
Module 6 – Muscular System
The Muscular System
Muscles are responsible for body movements, stabilizing joints, and generating heat.
Muscles generate the force required to cause movement by contracting, a process in which proteins inside the muscle fibers overlap more than when they are at rest
Muscles are needed to move substances inside our bodies: for example, air into and out of our lungs, food through our digestive tracts, and blood through our heart and blood vessels.
Muscle Types
Skeletal
Smooth
Cardiac
Similarities of all Muscle Types
Skeletal and smooth muscle cells are elongated.
The ability of muscle to shorten, or contract.
Terminology
Smooth Muscle - Smooth muscle has no striations and is involuntary. Found mainly in the walls of hollow (tubelike) visceral organs such as the stomach, urinary bladder, and respiratory passages, smooth muscle propels substances along a pathway. Smooth muscle contraction is slow and sustained.
Cardiac Muscle - Cardiac muscle is found in only one place in the body—the heart, where it forms the bulk of the heart walls. The heart serves as a pump, propelling blood through blood vessels to all body tissues.
Muscle Functions
Produce Movement
Maintain Posture and Body Position
Stabilize Joints
Generate Heat
Skeletal Muscle Activity: Stimulation and Contraction
Irritability
Contractility
Extensibility
The Nerve Stimulus and the Action Potential
To contract, skeletal muscle fibers must be stimulated by nerve impulses. One motor neuron (nerve cell) may stimulate a few muscle fibers or hundreds of them, depending on the particular muscle and the work it does.
Events at the Neuromuscular Junction
1. STIMULUS - Nerve impulse reaches axon terminal of motor neuron.
2. Calcium channels open, and calcium (Ca2+) enters the axon terminal.
3. Calcium entry causes some of the synaptic vesicles in the axon terminal to fuse with the cell membrane and release acetylcholine.
4. If enough acetylcholine is released, the sarcolemma at that point becomes temporarily even more permeable to sodium ions (Na+), which rush into the muscle fiber, and to potassium ions (K+), which diffuse out of the muscle fiber.
5. ACh binds and opens channels that allow simultaneous passage of Na+ into the muscle fiber and K+ out of the muscle fiber. The result is contraction of the muscle fiber.
6. The enzyme acetylcholinesterase breaks down ACh in the synaptic cleft, ending the process. A single nerve impulse produces only one contraction.
The Sliding Filament Theory - It explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement.
Contraction of a Skeletal Muscle as a whole
In skeletal muscles, the “all-or-none” law of muscle physiology applies to the muscle fiber, not to the whole muscle. It states that muscle fiber will contract to its fullest extent when it is stimulated adequately; it never partially contracts.
Graded Muscle Contractions can be produced two ways:
1. By changing the frequency of muscle stimulation
2. By changing the number of muscle fibers being stimulated at one time.
Muscle Response to Increasingly Rapid Stimulation:
1. Muscle twitches
2. Unfused tetanus (tet′ah-nus), or incomplete tetanus
3. Fused tetanus, or complete tetanus
3 Pathways to Regenerate ATP
Muscle Fatigue and Oxygen Deficit
• Muscle fatigue - Results from strenuous muscle activity.
• Oxygen deficit - The person is not able to take in oxygen fast enough to keep the muscles supplied with all the oxygen they need when they are working vigorously.
Types of Muscle Contraction: Isotonic and Isometric
1. Isotonic contractions - The myofilaments are successful in their sliding movements, the muscle shortens, and movement occurs.
2. Isometric contractions - The myosin filaments are “spinning their wheels,” (exerted) and the tension in the muscle keeps increasing. They are trying to slide, but the muscle is pitted against some more or less immovable object.
3. Muscle tone - Muscle tone is the result of different motor units, which are scattered through the muscle, being stimulated by the nervous system in a systematic way.
Effect of Exercise on Muscles
1. Aerobic exercise, or endurance exercise - It results in stronger, more flexible muscles with greater resistance to fatigue because the blood supply to the muscles increases, and the individual muscle fibers form more mitochondria and store more oxygen.
2. Resistance exercise, or isometric exercise - Bulging muscle is the result of forcing the muscles to contract with as much force as possible.
5 Basic Guidelines for Understanding Gross Muscle Activity (5 Golden Rules)
1. With a few exceptions, all skeletal muscles cross at least one joint.
2. Typically, the bulk of a skeletal muscle lies proximal to the joint crossed.
3. All skeletal muscles have at least two attachments: the origin and the insertion.
4. Skeletal muscles can only pull; they never push.
5. During contraction, a skeletal muscle insertion moves toward the origin.
Skeletal muscles are attached to bone, or to other connective tissue structures, at no fewer than two points. The origin is attached to the immovable or less movable bone. The insertion is attached to the movable bone. When the muscle contracts, the insertion moves toward the origin.
Most Common Types of Body Movements
Interactions of Skeletal Muscles in the Body
1. Prime mover - The muscle that has the major responsibility for causing a particular movement.
2. Antagonists/Agonist - Are muscles that oppose or reverse a movement.
3. Synergists - Help prime movers by producing the same movement or by reducing undesirable movements.
4. Fixators - Are specialized synergists, they hold a bone still or stabilize the origin of a prime mover so all the tension can be used to move the insertion bone.
Naming Skeletal Muscles
1. Direction of the muscle fibers
2. Relative size of the muscle
3. Location of the muscle
4. Number of origins
5. Location of the muscle’s origin and insertion
6. Shape of the muscle
7. Action of the muscle
Arrangements of Fascicles
Gross Anatomy of Skeletal Muscles
Head and Neck Muscles:
2 Large Categories
• Facial
• Chewing
Trunk Muscle:
The Trunk Muscles Includes:
1. Muscles that move the vertebral column (most of which are posterior antigravity muscles).
2. Anterior thorax muscles, which move the ribs, head, and arms.
3. Muscles of the abdominal wall, which “hold your guts in” by forming a natural girdle and help to move the vertebral column.
Muscles of the Upper Limb
1. Muscles that arise from the shoulder girdle and cross the shoulder joint to insert into the humerus.
2. Muscles that cause movement at the elbow joint.
3. Muscles of the forearm, which insert on the hand bones and cause their movement.
Muscles of the Lower Limb
1. Specialized for walking and balancing the body.
2. The terms origin and insertion are often interchangeable depending on the action being performed.
3. Muscles acting on the thigh are massive muscles that help hold the body upright against the pull of gravity and cause various movements at the hip joint.
4. Because many of the thigh muscles also have attachments on the pelvic girdle, they can cause movement at the hip joint.
Muscles Causing Movement at the Hip and knee Joint
Muscles Causing Movement at the Ankle and Foot
Developmental Aspects of the Muscular System
1. Increasing muscular control reflects the maturation of the nervous system. Muscle control is achieved in a superior/inferior and proximal/distal direction.
2. To remain healthy, muscles must be regularly exercised. Without exercise, they atrophy; with extremely vigorous exercise, they hypertrophy.
3. As we age, muscle mass decreases, and the muscles become sinewy. Exercise helps to retain muscle mass and strength.
Far Eastern University
Institute of Health Sciences and Nursing
Department of Nursing
NUR1101 - Anatomy and Physiology
Module 10 – Blood
Blood is a complex connective tissue in which living blood cells, the formed elements, are suspended in
plasma, a nonliving fluid matrix.
The reddish “pellet” is erythrocytes (erythro = red), or red blood cells, the formed elements that
function in oxygen transport.
Erythrocytes normally account for about 45 percent of the total volume of a blood sample, a percentage
known as the hematocrit (“blood fraction”). White blood cells and platelets contribute less than 1
percent, and plasma makes up most of the remaining 55 percent of whole blood.
Blood is unique: It is the only fluid tissue in the body. Although blood appears to be a thick,
homogeneous liquid, the microscope reveals that it has both solid and liquid components.
Physical Characteristics and Volume
• Blood is a sticky, opaque fluid that is heavier than water and about five times thicker, or more
viscous, largely because of its formed elements.
1
Far Eastern University
Institute of Health Sciences and Nursing
Department of Nursing
• The color of blood varies from scarlet (oxygen rich) to a dull red or purple (oxygen-poor).
• Blood has a characteristic metallic, salty taste. Blood is slightly alkaline, with a pH between 7.35
and 7.45.
• Its temperature (38°C, or 100.4°F) is always slightly higher than body temperature because of
the friction produced as blood flows through the vessels.
• Blood accounts for approximately 8 percent of body weight, and its volume in healthy adults is
5 to 6 liters.
Plasma, which is approximately 90 percent water, is the liquid part of the blood. Plasma proteins are the
most abundant solutes in plasma.
Formed Elements
• Erythrocytes, or red blood cells (RBCs), function primarily to ferry oxygen to all cells of the
body. Hemoglobin (Hb), an iron-bearing protein, transports most of the oxygen that is carried in
the blood. (It also binds with a small amount of carbon dioxide.)
• Leukocytes form a protective, movable army that helps defend the body against damage by
bacteria, viruses, parasites, and tumor cells. As such, they have some very special
characteristics.
2
Far Eastern University
Institute of Health Sciences and Nursing
Department of Nursing
• Platelets are not technically cells. They
are fragments of bizarre multinucleate
cells called megakaryocytes, which
pinch off thousands of anucleate
platelet “pieces” that quickly seal
themselves off from the surrounding
fluids.
Hematopoiesis (Blood Cell Formation)
Hematopoiesis occurs in red bone marrow, or
myeloid tissue. In adults, this tissue is found
chiefly in the axial skeleton, pectoral and pelvic
girdles, and proximal epiphyses of the humerus and femur.
The development of blood cells.
Blood cell formation, or hematopoiesis (hem″ahto-po-e′sis), occurs in red bone marrow, or myeloid
tissue. In adults, this tissue is found chiefly in the axial skeleton, pectoral and pelvic girdles, and proximal
epiphyses of the humerus and femur. Each type of blood cell is produced in different numbers in
response to changing body needs and different stimuli. After they mature, they are discharged into the
blood vessels surrounding the area. On average, the red marrow turns out an ounce of new blood
containing 100 billion new cells every day.
Formation of White Blood Cells and Platelets
Like erythrocyte production, the formation of leukocytes and platelets is stimulated by hormones. These
colony stimulating factors (CSFs) and interleukins not only prompt red bone marrow to turn out
leukocytes, but also enhance the ability of mature leukocytes to protect the body. Apparently, they are
released in response to specific chemical signals in the environment, such as inflammatory chemicals
and certain bacteria or their toxins. The hormone thrombopoietin accelerates the production of platelets
from megakaryocytes, but little is known about how that process is regulated.
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Mechanism for regulating the rate of RBC production.
The rate of erythrocyte production is controlled by a hormone called erythropoietin (˘e-rith″ro-po-
e′tin). Normally a small amount of erythropoietin circulates in the blood at all times, and red blood cells
are formed at a fairly constant rate. Although the liver produces some, the kidneys play the major role in
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producing this hormone. When the blood level of oxygen begins to decline for any reason, the kidneys
step up their release of erythropoietin. Erythropoietin targets the bone marrow, prodding it into “high
gear” to turn out more RBCs.
Hemostasis - Normally, blood flows smoothly past the intact lining (endothelium) of blood vessel walls.
But if a blood vessel wall breaks, a series of reactions starts the process of hemostasis (hem = blood;
stasis = standing still) or stopping the bleeding. This response, which is fast and localized, involves many
substances normally present in plasma, as well as some that are released by platelets and injured tissue
cells.
Phases of Hemostasis
Blood Groups and Transfusions
The plasma membranes of RBCs, like those of all other body cells, bear genetically determined proteins
(antigens), which identify each person as unique.
The “recognizers” are antibodies present in plasma that attach to RBCs bearing surface antigens
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different from those on the patient’s (recipient’s) RBCs. Binding of the antibodies causes the foreign
RBCs to clump, a phenomenon called agglutination, which leads to the clogging of small blood vessels
throughout the body. During the next few hours, the foreign RBCs are lysed (ruptured), and their
hemoglobin is released into the bloodstream.
The ABO blood groups are based on which of two antigens, type A or type B, a person inherits. Absence
of both antigens results in type O blood, presence of both antigens leads to type AB, and the presence of
either A or B antigen yields type A or B blood, respectively. In the ABO blood group, antibodies form
during infancy against the ABO antigens do not present on your own RBCs. As shown in the table, a baby
with neither the A nor the B antigen (group O) forms both anti-A and anti-B antibodies; those with type
A antigens (group A) form anti-B antibodies, and so on. To keep this idea straight, remember that
antibodies against a person’s own blood type will not be produced.
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Rh blood groups
The Rhesus (Rh) blood group system is a classification system for blood types, and it is one of the most
important in addition to the ABO blood group system. The Rh system is based on the presence or
absence of specific antigens on the surface of red blood cells.
The key component of the Rh system is the Rh antigen, also known as the Rh factor or D antigen. It is a
protein found on the surface of red blood cells. If a person's red blood cells have this antigen, they are
said to be Rh-positive (e.g., A+, B+). If the antigen is absent, they are Rh-negative (e.g., A-, B-).
The presence or absence of the Rh antigen is determined by genetic inheritance. The gene responsible
for the Rh factor is known as the RHD gene. A person inherits one copy of this gene from each parent. If
both copies have the Rh antigen (D), the person is Rh-positive. If one or both copies lack the Rh antigen,
the person is Rh-negative.
Rh-negative individuals who are exposed to Rh-positive blood (e.g., through a transfusion or during
pregnancy) can develop antibodies against the Rh antigen. This is known as Rh sensitization and can
cause problems in future pregnancies if the mother's immune system attacks an Rh-positive fetus's red
blood cells.
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Blood Typing
The general procedure for determining ABO blood type essentially involves testing the blood by mixing
it with two different types of immune serum—anti-A and anti-B In order to double check compatibility,
cross matching is also done.
Cross matching involves testing for agglutination of donor RBCs by the recipient’s serum and of the
recipient’s RBCs by the donor serum. Typing for the Rh factors is done in the same manner as ABO blood
typing.
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NUR1101 - Anatomy and Physiology
Module 11 – The Cardiovascular System
The major function of the cardiovascular system is transportation. Using blood as the transport vehicle,
the system carries oxygen, nutrients, cell wastes, hormones, and many other substances vital for body
homeostasis to and from the cells. The force to move the blood around the body is provided by the
beating heart and by blood pressure.
The Heart
Approximately the size of a person’s fist, the hollow, cone-shaped heart weighs less than a pound.
Snugly enclosed within the inferior mediastinum, the medial section of the thoracic cavity, the heart is
flanked on each side by the lungs. Its pointed apex is directed toward the left hip and rests on the
diaphragm, approximately at the level of the fifth intercostal space. Its broad posterosuperior aspect, or
base, from which the great vessels of the body emerge, points toward the right shoulder and lies
beneath the second rib.
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Coverings and Walls of the Heart
The heart is enclosed by a sac called the pericardium (per″i-kar′de-um) that is made up of three layers:
an outer fibrous layer and an inner serous membrane pair. This fibrous layer helps protect the heart and
anchors it to surrounding structures, such as the diaphragm and sternum.
The visceral layer of the serous pericardium, or visceral pericardium, also called the epicardium, is part
of the heart wall. In other words, the epicardium is the innermost layer of the pericardium and the
outermost layer of the heart wall.
The heart walls are composed of three layers: the outer epicardium, the myocardium, and the innermost
endocardium.
Chambers and Associated Great Vessels
The heart has four hollow cavities, or chambers—two atria (a′tre-ah; singular atrium) and two ventricles
(ven′tr˘ı-kulz). Each of these chambers is lined with endocardium, which helps blood flow smoothly
through the heart.
Although it is a single organ, the heart functions as a double pump, with arteries carrying blood away
from and veins carrying blood toward the heart. The right side works as the pulmonary circuit pump.
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Oxygen-rich blood returned to the left atrium flows into the left ventricle and is pumped out into the
aorta (a-or′tah), from which the systemic arteries branch to supply essentially all body tissues.
The systemic and Pulmonary Circulation
This circuit, from the right ventricle (the pump) to
the lungs and back to the left atrium (receiving
chamber), is called the pulmonary circulation. Its
only function is to carry blood to the lungs for gas
exchange.
The second circuit, from the left ventricle through
the body tissues and back to the right atrium, is
called the systemic circulation. It supplies oxygen-
and nutrient-rich blood to all body organs.
Heart Valves
The heart is equipped with four valves, which allow
blood to flow in only one direction through the heart
chambers—from the atria through the ventricles and
out the great arteries leaving the heart.
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The atrioventricular (AV) valves (a″tre-o-ven-trik′u-lar) are located between the atria and ventricles on
each side. These valves prevent backflow into the atria when the ventricles contract. The left AV
valve—the bicuspid valve, also called the mitral (mi′tral) valve—consists of two flaps, or cusps, of
endocardium. The right AV valve, the tricuspid valve, has three cusps. Tiny white cords, the chordae
tendineae (kor′de ten-din′e)—literally, “tendinous cords” (think of them as “heart strings”)—anchor the
cusps to the walls of the ventricles.
The second set of valves, the semilunar (sem″˘ı-lu′nar) valves, guards the bases of the two large arteries
leaving the ventricular chambers. Thus, they are known as the pulmonary semilunar valve and aortic
semilunar valve.
Each set of valves operates at a different time. The AV valves are open during heart relaxation and
closed when the ventricles are contracting. The semilunar valves are closed during heart relaxation
and are forced open when the ventricles contract. The valves force blood to continually move forward
through the heart by opening and closing in response to pressure changes in the heart.
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Operation of the AV valves
Operation of the semilunar valves
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Cardiac Circulation
The functional blood supply that oxygenates and nourishes the myocardium is provided by the right and
left coronary arteries. The coronary arteries branch from the base of the aorta and encircle the heart in
the coronary sulcus (atrioventricular groove) at the junction of the atria and ventricles.
Physiology of the Heart
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What makes the heart beats? Unlike skeletal muscle cells, which must be stimulated by nerve impulses
before they will contract, cardiac muscle cells can and do contract spontaneously and independently,
even if all nervous connections are severed. Moreover, these spontaneous contractions occur in a
regular and continuous way. Although cardiac muscle can beat independently, the muscle cells in
different areas of the heart have different rhythms. Atrial cells beat about 60 times per minute, but
ventricular cells contract more slowly (20–40 times per minute). Therefore, without some type of
unifying control system, the heart would be an uncoordinated and inefficient pump.
Two systems act to regulate heart activity. One of these involves the nerves of the autonomic nervous
system, which act like brakes and gas pedals to decrease or increase the heart rate, depending on which
division is activated. The second system is the intrinsic conduction system, or nodal system, that is built
into the heart tissue and sets its basic rhythm.
One of the most important parts of the intrinsic conduction system is a crescent-shaped node of tissue
called the sinoatrial (si″no-a′tre-al) (SA) node, located in the right atrium. Other components include
the atrioventricular (AV) node at the junction of the atria and ventricles, the atrioventricular (AV)
bundle (bundle of His) and the right and left bundle branches located in the interventricular septum,
and finally the Purkinje (pur-kin′je) fibers, which spread within the myocardium of the ventricle walls.
The SA node is a tiny cell mass with a mammoth job. Because it has the highest rate of depolarization in
the whole system, it starts each heartbeat and sets the pace for the whole heart. Consequently, the SA
node is often called the pacemaker.
Cardiac Cycle
The term cardiac cycle refers to the events of one complete heartbeat, during which both atria and
ventricles contract and then relax. The average heart beats approximately 75 times per minute, so the
length of the cardiac cycle is normally about 0.8 second. We will consider the cardiac cycle in terms of
events occurring during five periods.
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Cardiac Output
Cardiac output (CO) is the amount of blood pumped out by each side of the heart (actually each
ventricle) in 1 minute. It is the product of the heart rate (HR) and the stroke volume (SV). Stroke volume
is the volume of blood pumped out by a ventricle with each heartbeat. In general, stroke volume
increases as the force of ventricular contraction increases. If we use the normal resting values for heart
rate (75 beats per minute) and stroke volume (70 ml per beat), the average adult cardiac output can be
easily calculated:
CO = HR (75 beats/min) × SV (70 ml/beat)
CO = 5250 ml/min = 5.25 L/min
Regulation of Stroke Volume A healthy heart pumps out about 60 percent of the blood present in its
ventricles. As noted previously, this is approximately 70 ml (about 2 ounces) with each heartbeat.
According to Starling’s law of the heart, the critical factor controlling stroke volume is how much the
cardiac muscle cells are stretched by the filling of the chambers just before they contract. The more they
are stretched, the stronger the contraction will be. The important factor stretching the heart muscle is
venous return, the amount of blood entering the heart and distending its ventricles. If one side of the
heart suddenly begins to pump more blood than the other, the increased venous return to the opposite
ventricle will force it to pump out an equal amount, thus preventing backup of blood in the circulation.
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Influence of selected factors on cardiac output
Factors Modifying Basic Heart Rate
1. Neural (ANS) controls.
2. Hormones and ions.
3. Physical factors.
Electrocardiography
The heart’s electrical activity produces currents that radiate through the surrounding tissue to the skin.
When electrodes are attached to the skin, they sense those electrical currents and transmit them to an
ECG monitor. The currents are then transformed into waveforms that represent the heart’s
depolarization repolarization cycle.
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The typical ECG has three recognizable waves. The first wave, which follows the firing of the SA node, is
the P wave. The P wave is small and signals the depolarization of the atria immediately before they
contract. The large QRS complex, which results from the depolarization of the ventricles, has a
complicated shape. It precedes the contraction of the ventricles. The T wave results from currents
flowing during the repolarization of the ventricles. (Atrial repolarization is generally hidden by the large
QRS complex, which is being recorded at the same time).
2 Types of ECG
• 12-lead ECG
• Rhythm strip
Different leads provide different information.
The six limb leads—I, II, III, augmented vector
right (aVR), augmented vector left (aVL), and
augmented vector foot (aVF)—provide
information about the heart’s frontal (vertical)
plane. Leads I, II, and III require a negative and
positive electrode for monitoring, which makes
those leads bipolar. The augmented leads record information from one lead and are called unipolar.
lead I
Lead I provide a view of the heart that shows current moving from right to left. Because current flows
from negative to positive, the positive electrode for this lead is placed on the left arm or on the left side
of the chest; the negative electrode is placed on the right arm.
lead II
Lead II produces a positive deflection. Place the positive electrode on the patient’s left leg and the
negative electrode on the right arm. The current travels down and to the left in this lead. Lead II tends to
produce a positive, high voltage deflection, resulting in tall P, R, and T waves.
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lead III
Lead III produces a positive deflection. The positive electrode is placed on the left leg; the negative
electrode, on the left arm.
Leads aVR, aVL, and aVF are called augmented leads because the small waveforms that normally would
appear from these unipolar leads are enhanced by the ECG. The “a” stands for “augmented,” and “R, L,
and F” stand for the positive electrode position of the lead. In lead aVR, the positive electrode is placed
on the right arm (hence, the R) and produces a negative deflection because the heart’s electrical activity
moves away from the lead. In lead aVL, the positive electrode is on the left arm and produces a positive
deflection on the ECG. In lead aVF, the positive electrode is on the left leg (despite the name aVF) and
produces a positive deflection. These three limbs lead also provide a view of the heart’s frontal plane.
The six precordial or V leads—V1, V2, V3, V4, V5, and V6—provide information about the heart’s
horizontal plane. Like the augmented leads, the precordial leads are also unipolar, requiring only a single
electrode. The opposing pole of those leads is the center of the heart as calculated by the ECG.
Lead V1—The precordial lead V1 electrode is placed on the right side of the sternum at the fourth
intercostal rib space. This lead corresponds to the modified chest lead MCL1 and shows the P wave, QRS
complex, and ST segment particularly well.
Lead V2—Lead V2 is placed at the left of the sternum at the fourth intercostal rib space.
Lead V3—Lead V3 goes between V2 and V4. Leads V1, V2, and V3 are biphasic, with both positive and
negative deflections. Leads V2 and V3 can be used to detect ST-segment elevation.
Lead V4—Lead V4 is placed at the fifth intercostal space at the midclavicular line and produces a
biphasic waveform.
Lead V5—Lead V5 is placed at the fifth intercostal space at the anterior axillary line. It produces a
positive deflection on the ECG and, along with V4, can show changes in the ST segment or T wave.
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Lead V6—Lead V6, the last of the precordial leads, is placed level with V4 at the midaxillary line. This
lead produces a positive deflection on the ECG.
12 Lead ECG Electrode Placement
The principle behind Einthoven's triangle describes how electrodes RA, LA and LL do not only record the
electrical activity of the heart in relation to themselves through the aVR, aVL and aVF leads. They also
correspond with each other to form leads I (RA to LA), II (RA to LL) and III (LL to LA).
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Pre-procedure Routines
• Ensure that electronic devices (e.g., smartphone) are removed from the patient. These devices
can produce artifact (interference) and cause problems with the readings.
• Place patient in supine or Semi-Fowler's position. If both positions are impossible, you can
perform ECG with the patient in a more elevated position.
• With arms lying flat on the side, ask the patient to relax the shoulders and keep the legs
uncrossed.
• Unless you're performing a stress ECG test, ask the patient to lie still and quietly until the test is
done.
• For patients that do not fit comfortably on the bed or exam table due to size, ask them to cross
their arms on their stomach to reduce muscle tension and movement.
• Skin should be dry, hairless, and oil-free. Shave hair that can possibly impede electrode
placement. Electrodes should have full contact with the patient's skin.
• For better electrode adhesion and oil-free skin, rub the area with an alcohol prep pad or gauze
paid with benzoin tincture.
• Reduce electrical resistance minus the skin redness with 5 to 10 gentle strokes. This will help
ensure that the heart's electrical signals are transmitted to the electrodes.
• Promote an environment that prevents the patient from sweating profusely.
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Blood Vessels
As the heart beats, it propels blood into the large arteries leaving the heart. As the large arteries branch,
blood moves into successively smaller and smaller arteries and then into the arterioles (ar-ter′e-ˉolz),
which feed the capillary (kap′˘ı-lar″e) beds in the tissues. Capillary beds are drained by venules
(ven′ulz), which in turn empty into veins that merge and finally empty into the great veins (venae cavae)
entering the heart.
Except for the microscopic capillaries (which have only one layer), the walls of blood vessels have three
layers, or tunics. The tunica intima, tunica media, and tunica externa.
Structural Differences in Arteries, Veins, and Capillaries
1. 2. 3. 4. The walls of arteries are usually much thicker than those of veins.
Skeletal muscle activity, known as the muscular pump, also enhances venous return.
The transparent walls of the capillaries are only one cell layer thick—just the tunica intima.
The true capillaries number 10 to 100 per capillary bed, depending on the organ or tissues
served.
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Anatomy of a capillary bed
The transparent walls of the capillaries are only one cell layer thick—just the tunica intima. Because of
this exceptional thinness, substances are exchanged easily between the blood and the tissue cells. The
tiny capillaries tend to form interweaving capillary beds. The flow of blood from an arteriole to a
venule—that is, through a capillary bed—is called microcirculation. In most body regions, a capillary
bed consists of two types of vessels: (1) a vascular shunt, a vessel that directly connects the arteriole
and venule at opposite ends of the bed, and (2) true capillaries, the actual exchange vessels.
Capillary Exchange of Gases and Nutrients
1. Direct diffusion through membrane.
2. Diffusion through intercellular clefts.
3. Diffusion through pores.
4. Transport via vesicles
Fluid Movements at Capillary Beds
Because of their intercellular clefts and
fenestrations, some capillaries are leaky,
and bulk fluid flow (fluid moving all at once)
occurs across their plasma membranes.
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Blood pressure tends to force fluid (and solutes) out of the capillaries, and osmotic pressure tends to
draw fluid into them because blood has a higher solute concentration (due to its plasma proteins) than
does interstitial fluid. Whether fluid moves out of or into a capillary depends on the difference between
the two pressures. As a rule, blood pressure is higher than osmotic pressure at the arterial end of the
capillary bed, and lower than osmotic pressure at the venous end. Consequently, fluid moves out of the
capillaries at the beginning of the bed and is reclaimed at the opposite (venule) end. However, not quite
all of the fluid forced out of the blood is reclaimed at the venule end. Returning fluid left in tissues to the
blood is the chore of the lymphatic system.
Arterial Supply of the Brain and the Circle of Willis
Because a lack of blood for even a few minutes causes the delicate brain cells to die, a continuous blood
supply to the brain is crucial. The brain is supplied by two pairs of arteries, the internal carotid arteries
and the vertebral arteries.
The internal carotid arteries, branches of the common carotid arteries, run through the neck and enter
the skull through the temporal bone. Once inside the cranium, each divides into the anterior cerebral
artery and middle cerebral artery, which supply most of the cerebrum.
The paired vertebral arteries pass upward from the subclavian arteries at the base of the neck. Within
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the skull, the vertebral arteries join to form the single basilar artery. This artery serves the brain stem
and cerebellum as it travels upward. At the base of the cerebrum, the basilar artery divides to form the
posterior cerebral arteries, which supply the posterior part of the cerebrum.
The anterior and posterior blood supplies of the brain are united by small communicating arterial
branches. The result is a complete circle of connecting blood vessels called the cerebral arterial circle or
the circle of Willis, which surrounds the base of the brain. The cerebral arterial circle protects the brain
by providing more than one route for blood to reach brain tissue in case of a clot or impaired blood flow
anywhere in the system.
Hepatic Portal Circulation
The veins of the hepatic portal circulation drain the digestive organs, spleen, and pancreas and deliver
this blood to the liver through the hepatic portal vein.
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Hepatic Portal Circulation
The major vessels composing the hepatic portal circulation include the inferior and superior mesenteric
veins, the splenic vein, and the left gastric vein. The inferior mesenteric vein, draining the terminal part
of the large intestine, drains into the splenic vein, which itself drains the spleen, pancreas, and the left
side of the stomach. The splenic vein and superior mesenteric vein (which drains the small intestine and
the first part of the colon) join to form the hepatic portal vein. The L. gastric vein, which drains the right
side of the stomach, drains directly into the hepatic portal vein.
Physiology of Circulation
The alternating expansion and recoil of an artery that occurs with each beat of the left ventricle creates a
pressure wave—a pulse—that travels through the entire arterial system. Normally the pulse rate
(pressure surges per minute) equals the heart rate (beats per minute). The pulse averages 70 to 76 beats
per minute in a healthy resting person. It is influenced by activity, postural changes, and emotions. You
can feel a pulse in any artery lying close to the body surface by compressing the artery against firm
tissue; this provides an easy way of counting heart rate. Because it is so accessible, the point where the
radial artery surfaces at the wrist (the radial pulse) is routinely used to take a pulse measurement, but
there are several other clinically important arterial pulse points. Because these same points are
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compressed to stop blood flow into distal tissues during significant blood loss or hemorrhage, they are
also called pressure points.
Blood Pressure
Blood pressure is the pressure the blood exerts
against the inner walls of the blood vessels, and
it is the force that keeps blood circulating
continuously even between heartbeats.
Blood Pressure Gradient When the ventricles
contract, they force blood into large, thick-
walled elastic arteries close to the heart that
expand as the blood is pushed into them. The
high pressure in these elastic arteries forces the
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blood to continuously move into areas where the pressure is lower. The pressure is highest in the large
arteries closest to the heart and continues to drop throughout the systemic pathway, reaching zero at
the right atrium.
Measuring Blood Pressure
Two arterial blood pressures are usually measured: systolic (sis-t˘o′lik) pressure, the pressure in the
arteries at the peak of ventricular contraction, and diastolic (di″us-t˘o′lik) pressure, the pressure when
the ventricles are relaxing. Blood pressures are reported in millimeters of mercury (mm Hg), with the
higher systolic pressure written first—120/80 (read “120 over 80”) translates to a systolic pressure of
120 mm Hg and a diastolic pressure of 80 mm Hg. Most often, systemic arterial blood pressure is
measured indirectly by the auscultatory (os-kul′tuh-tor-e) method. This procedure is used to measure
blood pressure in the brachial artery of the arm.
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Arterial blood pressure (BP) is directly related to cardiac output (CO; the amount of blood pumped out
of the left ventricle per minute) and peripheral resistance (PR). This relationship is expressed by the
equation BP = CO × PR. We have already considered regulation of cardiac output, so we will concentrate
on peripheral resistance here.
Peripheral resistance is the amount of friction the blood encounters as it flows through the blood
vessels.
1. Neural factors: the autonomic nervous system.
2. Renal factors: the kidneys.
3. Temperature.
4. Chemicals.
5. Diet
Neural factors: the autonomic nervous system.
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NUR1101 - Anatomy and Physiology
Module 13 – The Respiratory System
Functional Anatomy of the Respiratory System
The organs of the respiratory system include the nose, pharynx, larynx, trachea, bronchi and their
smaller branches, and the lungs, which contain the alveoli (al-ve′o-li), or terminal air sacs.
The passageways from the nose to the larynx are called the upper respiratory tract, and those from the
trachea to the alveoli are the lower respiratory tract.
The nose, whether “button” or “hooked” in shape, is the only externally visible part of the respiratory
system.
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During breathing, air enters the nose by passing through the nostrils, or nares. The interior of the nose
consists of the nasal cavity, divided by a midline nasal septum. The olfactory receptors for the sense of
smell are located in the mucosa in the slit like superior part of the nasal cavity, just beneath the ethmoid
bone.
The rest of the mucosa lining the nasal cavity, called the respiratory mucosa, rests on a rich network of
thin-walled veins that warms the air as it flows past. The lateral walls of the nasal cavity are uneven,
owing to three mucosa-covered projections, or lobes, called conchae (kong′ke). The conchae greatly
increase the surface area of the mucosa exposed to the air.
The nasal cavity is separated from the oral cavity below by a partition, the palate (pal′et).
The Pharynx and the Larynx
The pharynx (far′inks) – throat, is a muscular passageway about 13 cm (5 inches) long that vaguely
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resembles a short length red garden hose. The pharynx serves as a common passageway for food and
air. It is continuous with the nasal cavity anteriorly via the posterior nasal aperture.
The pharynx has three regions. Air enters the superior portion, the nasopharynx (na″zo-far′inks), from
the nasal cavity and then descends through the oropharynx (o″ro-far′inks) and laryngopharynx (lah-
ring″go-far′inks) to enter the larynx below. Food enters the mouth, then travels along with air through
the oropharynx and laryngopharynx. But instead of entering the larynx, food is directed into the
esophagus (˘e-sof′ah-gus) posteriorly by a flap called the epiglottis (ep″˘ı-glot′is). The
pharyngotympanic tubes, which drain the middle ears, open into the nasopharynx.
Clusters of lymphatic tissue called tonsils are also found in the pharynx. The single pharyngeal (far-rin′je-
al) tonsil, often called the adenoid, is located high in the nasopharynx. The two palatine tonsils are in
the oropharynx at the end of the soft palate, as are the two lingual tonsils, which lie at the base of the
tongue. The tonsils also play a role in protecting the body from infection.
The larynx (lar′inks), or voice box, routes air and food into the proper channels and plays a role in
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speech. The larynx houses the vocal cords. There are two sets of ligaments that extend from the
posterior surface of the thyroid cartilage to the paired cartilages. The superior set of ligaments forms
the vestibular (ves-tib′ ū-lăr) folds, or false vocal cords, and the inferior set of ligaments composes the
vocal folds, or true vocal cords.
The trachea is fairly rigid because its walls are reinforced with C-shaped rings of hyaline cartilage. The
cilia are the yellow, grass like projections surrounded by the mucus-secreting goblet cells, which exhibit
short microvilli (orange).
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The Main Bronchi
The right and left main (primary) bronchi (brong′ki) are formed by the division of the trachea. Each main
bronchus runs obliquely before it plunges into the medial depression (hilum) of the lung on its own side.
The right main bronchus is wider, shorter, and straighter than the left.
The Lungs
the mediastinum (me″de-as-ti′num), which houses the heart, the great blood vessels, bronchi, the
The lungs are fairly large organs. They occupy the entire thoracic cavity except for the most central area,
esophagus, and other organs.
The narrow superior portion of each lung, the apex, is just deep to the clavicle. The broad lung area
resting on the diaphragm is the base. Each lung is divided into lobes by fissures; the left lung has two
lobes, and the right lung has three.
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The surface of each lung is covered with its own visceral serosa, called the pulmonary pleura or visceral
pleura (ploor′ah), and the walls of the thoracic cavity are lined by the parietal pleura.
The pleural membranes produce pleural fluid, slippery serous fluid, which allows the lungs to glide easily
over the thorax wall during breathing and causes the two pleural layers to cling together.
The pleurae can slide easily from
side to side across one another, but
they strongly resist being pulled
apart.
Consequently, the lungs are held
tightly to the thorax wall, and the
pleural space is more of a potential
space than an actual one.
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The Bronchial Tree
After entering the lungs, the main bronchi subdivide into smaller and smaller branches (secondary and
tertiary bronchi, and so on), finally ending in the smallest of the conducting passageways, the
bronchioles (brong′ke-ˉolz).
The terminal bronchioles lead into respiratory zone structures, even smaller conduits that eventually
terminate in alveoli (al-ve′o-li; alveol = small cavity), or air sacs. The respiratory zone, which includes the
respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, is the only site of gas exchange.
Respiratory Zone Structures
All other respiratory passages are conducting zone structures that serve as conduits to and from the
respiratory zone. There are millions of clustered alveoli, which resemble bunches of grapes, and they
make up the bulk of the lungs. Consequently, the lungs are mostly air spaces. The balance of the lung
tissue, its stroma, is mainly elastic connective tissue that allows the lungs to stretch and recoil (spring
back) as we breathe.
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Functional Anatomy of the Respiratory Membrane (air-blood barrier)
The walls of the alveoli are composed largely of a single, thin layer of simple squamous epithelial cells.
The thinness of their walls is hard to imagine, but a sheet of tissue paper is much thicker. Alveolar pores
connect neighboring air sacs and provide alternative routes for air to reach alveoli whose feeder
bronchioles have been clogged by mucus or otherwise blocked. The external surfaces of the alveoli are
covered with a “cobweb” of pulmonary capillaries. Together, the alveolar and capillary walls, their fused
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basement membranes, and occasional elastic fibers construct the respiratory membrane (air-blood
barrier).
Gas exchange occurs by simple diffusion through the respiratory membrane—oxygen passes from the
alveolar air into the capillary blood, and carbon dioxide leaves the blood to enter the alveoli.
The final line of defense for the respiratory system is within the alveoli. Remarkably efficient alveolar
macrophages, sometimes called “dust cells,” wander in and out of the alveoli picking up bacteria,
carbon particles, and other debris. Also scattered amid the epithelial cells that form most of the alveolar
walls are cuboidal surfactant-secreting cells, which look very different from the squamous epithelial
cells. These cells produce a lipid (fat) molecule called surfactant, which coats the gas exposed alveolar
surfaces and is very important in lung function.
Respiratory Physiology
Four distinct events of respiration:
1. Pulmonary ventilation.
2. External respiration
3. Respiratory gas transport
4. Internal respiration.
Mechanics of Breathing
Inspiration
When the inspiratory muscles, the diaphragm and external intercostals contract, the size of the thoracic
cavity increases. As the dome-shaped diaphragm contracts inferiorly, the superior-inferior dimension
(height) of the thoracic cavity increases.
Expiration
Expiration (exhalation) in healthy people is largely a passive process that depends more on the natural
elasticity of the lungs than on muscle contraction
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Respiratory Volumes and Capacities
Many factors affect respiratory capacity—for example, a person’s size, sex, age, and physical condition.
Tidal volume (TV) - Normal quiet breathing moves approximately 500 ml of air (about a pint) into and
out of the lungs with each breath.
Inspiratory reserve volume (Irv) - As a rule, a person is capable of inhaling much more air than is taken
in during a tidal breath. The amount of air that can be taken in forcibly above the tidal volume is around
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3,100 ml.
Expiratory Reserve volume (ERV) - after a normal expiration, more air can be exhaled. The amount of
air that can be forcibly exhaled beyond tidal expiration is 1200ml.
Residual volume - Even after the most strenuous expiration, about 1,200 ml of air still remains in the
lungs and cannot voluntarily be expelled. Residual volume air is important because it allows gas
exchange to go on continuously even between breaths and helps to keep the alveoli open (inflated).
Vital capacity (VC) - The total amount of exchangeable air (around 4,800 ml in healthy young men and
3,100 ml in healthy young women). The vital capacity is the sum of the tidal volume plus the inspiratory
and expiratory reserve volumes. Respiratory volumes of a male are summarized.
Note that some of the air that enters the respiratory tract remains in the conducting zone passageways
and never reaches the alveoli. This is called the dead space volume and during a normal tidal breath is
about 150 ml. The functional volume—air that actually reaches the respiratory zone and contributes to
gas exchange—is about 350 ml.
Non-respiratory Air Movements
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External Respiration, Gas Transport, and Internal Respiration
External respiration is the actual exchange of
gases between the alveoli and the blood
(pulmonary gas exchange), and internal
respiration is the gas exchange process that
occurs between the blood and the tissue cells
(systemic capillary gas exchange).
All gas exchanges obey the laws of diffusion;
that is, movement occurs toward the area of
lower concentration of the diffusing substance.
External Respiration
During external respiration, dark red blood
flowing through the pulmonary circuit is
transformed into the scarlet river that is
returned to the heart for distribution to the
systemic circuit.
As tissue cells remove oxygen from the blood in
the systemic circulation, they release carbon
dioxide into the blood. Because the
concentration of carbon dioxide is much higher
in the pulmonary capillaries than it is in the
alveolar air, it will diffuse from the blood into
the alveoli and be flushed out of the lungs
during expiration. Relatively speaking, blood
draining from the lungs into the pulmonary
veins is rich in oxygen and poor in carbon
dioxide.
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The loading and unloading of oxygen and carbon dioxide in the body.
Internal Respiration
Internal respiration, the exchange of gases between the blood and the tissue cells, is the opposite of
what occurs in the lungs. In this process, oxygen leaves and carbon dioxide enter the blood.
Control of Respiration
The activity of the respiratory muscles, the diaphragm and external intercostals, is regulated by nerve
impulses transmitted from the brain by the phrenic nerves and intercostal nerves. Neural centers that
control respiratory rhythm and depth are located mainly in the medulla and pons.
The medulla contains two respiratory centers. The first, the ventral respiratory group (VRG), contains
both inspiratory and expiratory neurons that alternately send impulses to control the rhythm of
breathing. The inspiratory neurons stimulate the diaphragm and external intercostal muscles via the
phrenic and intercostal nerves, respectively, during quiet breathing. Impulses from the expiratory
neurons stop the stimulation of the diaphragm and external intercostal muscles, allowing passive
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exhalation to occur. Impulses from the VRG maintain a normal quiet breathing rate of 12 to 15
respirations/ minute, a rate called eupnea (ˉup-ne′ah).
The other medullary center, the dorsal respiratory group (DRG), integrates sensory information from
chemoreceptors and peripheral stretch receptors. The DRG communicates this information to the VRG
to help modify breathing rhythms.
Neural Regulation: Setting the Basic Rhythm
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Nonneural Factors Influencing Respiratory Rate and Depth
1. Physical Factors
2. Volition (Conscious Control)
3. Emotional Factors
4. Chemical Factors
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Anatomy and Physiology
Module 14 – The Digestive System and Body Metabolism
The digestive system breaks down the food you eat into nutrients needed for metabolic processes, such
as making ATP, and rids the body of materials that cannot be used, such as fiber.
The digestive system is essential for providing the body with the energy and building blocks it requires to
maintain life.
Chewing breaks down food into small pieces easy for enzymes to access; enzymes then chemically digest
food into nutrients that are actively transported into blood and delivered to cells around the body.
Functions:
• ingests food (takes it in)
• digests it (breaks it down)
• absorbs the nutrients.
• defecates (excretes)
Anatomy and physiology of the digestive system
The alimentary canal, also called the gastrointestinal (GI) tract or gut, is a continuous, coiled, hollow
muscular tube that winds through the ventral body cavity from mouth to anus.
2 main groups:
• the alimentary (aliment = nourish) canal
• the accessory digestive organs
Its organs are the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. ***The
large intestine leads to the terminal opening, or anus. In a cadaver, the alimentary canal is
approximately 9 m (about 30 feet) long, but in a living person, it is considerably shorter because of its
muscle tone.
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Organs of the Alimentary Canal:
Mouth
Food enters the digestive tract through the mouth, or oral cavity, a mucous membrane–lined cavity.
Pharynx
--- The pharynx is subdivided into the nasopharynx, part of the respiratory passageway; the
oropharynx, posterior to the oral cavity; and the laryngopharynx, which is continuous with the
esophagus inferiorly.
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Esophagus
--- The esophagus, or gullet, runs from the pharynx through the diaphragm to the stomach. About 25 cm
(10 inches) long, it is essentially a passageway that conducts food (by peristalsis) to the stomach.
The walls of the alimentary canal
The walls of the alimentary canal organs from the esophagus to the large intestine are made up of the
same four tissue layers, or tunics. It consists primarily of surface epithelium plus a small amount of
connective tissue (lamina propria) and a scanty smooth muscle layer. Beyond the esophagus, which has
a friction-resisting stratified squamous epithelium, the epithelium is mostly simple columnar.
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Stomach
The C-shaped stomach is on the left side of the abdominal cavity, nearly hidden by the liver and
diaphragm.
The stomach acts as a temporary “storage tank” for food as well as a site for food breakdown.
This arrangement allows the stomach not only to move food along the tract, but also to churn, mix, and
pummel the food, physically breaking it down into smaller fragments. In addition, chemical breakdown
of proteins begins in the stomach.
The lesser omentum, a double layer of peritoneum, extends from the liver to the lesser curvature of the
stomach. The greater omentum, another extension of the peritoneum, drapes downward and covers
the abdominal organs like a lacy apron before attaching to the posterior body wall.
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The mucosa of the stomach is a simple columnar epithelium composed entirely of mucous cells. ***
They produce a protective layer of bicarbonate rich alkaline mucus that clings to the stomach mucosa
and protects the stomach wall from being damaged by acid and digested by enzymes.
Small Intestine
The small intestine is the body’s major digestive organ. The small intestine is a muscular tube extending
from the pyloric sphincter to the large intestine. It is the longest section of the alimentary tube, with an
average length of 2 to 4 m (7 to 13 feet) in a living person. Except for the initial part of the small
intestine, which mostly lies in a retroperitoneal position (posterior to the parietal peritoneum), the small
intestine hangs in sausage like coils in the abdominal cavity, suspended from the posterior abdominal
wall by the fan-shaped mesentery. The large intestine encircles and frames it in the abdominal cavity.
Within its twisted passageways, usable nutrients are finally prepared for their journey into the cells of
the body.
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The duodenum of the small intestine and related organs
Nearly all nutrient absorption occurs in the small intestine. The small intestine is well suited for its
function. Its wall has three structures that increase the absorptive surface tremendously—villi, microvilli,
and circular folds.
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Villi are fingerlike projections of the mucosa that give it a velvety appearance and feel, much like the
soft nap of a towel. Within each villus is a rich capillary bed and a modified lymphatic capillary called a
lacteal.
Microvilli are tiny projections of the plasma membrane of the mucosa cells that give the cell surface a
fuzzy appearance, sometimes referred to as the brush border.
Circular folds, also called plicae circulares (pli′se ser-ku-la′res), are deep folds of both mucosa and
submucosa layers. *** Unlike the rugae of the stomach, the circular folds do not disappear when food
fills the small intestine.
Large Intestine
The large intestine is much larger in diameter than the small intestine (thus its name) but shorter in
length. About 1.5 m (5 feet) long, it extends from the ileocecal valve to the anus.
Its major functions are to dry out the indigestible food residue by absorbing water and to eliminate
these residues from the body as feces (fe′sˉez).
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Accessory Digestive Organs
Teeth
We masticate, or chew, by opening and closing our jaws and moving them from side to side while
continuously using our tongue and cheek muscles to keep the food between our teeth. In the process,
the teeth tear and grind the food, breaking it down into smaller fragments.
By the age of 21, two sets of teeth have been formed. The first set are deciduous teeth, also called baby
teeth or milk teeth. The deciduous teeth begin to erupt around 6 months; the first teeth to appear are
the lower central incisors. A baby has a full set (20 teeth) by the age of 2 years.
We classify teeth according to shape and function as incisors, canines, premolars, and molars. *** The
chisel-shaped incisors are adapted for cutting; the fanglike canines (eyeteeth) are for tearing or piercing.
The premolars (bicuspids) and molars have broad crowns with rounded cusps (tips) and are best suited
for crushing and grinding.
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Salivary Glands
Three pairs of salivary glands empty their secretions into the mouth. The large parotid (pahrot′ id)
glands lie anterior to the ears. The submandibular glands and the small sublingual (sub-ling′gwal) glands
empty their secretions into the floor of the mouth through tiny ducts. The product of the salivary glands,
saliva, is a mixture of mucus and serous fluids.
Pancreas, Liver and Gallbladder
The pancreas is a soft, pink, triangular gland that extends across the abdomen from the spleen to the
duodenum. Only the pancreas produces enzymes that break down all categories of digestible foods. The
pancreatic enzymes are secreted into the duodenum in an alkaline fluid that neutralizes the acidic
chyme coming in from the stomach. The pancreas also has an endocrine function; it produces the
hormones insulin and glucagon.
The liver is the largest gland in the body. The liver has many critical metabolic and regulatory roles;
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however, its digestive function is to produce bile. Bile is a yellow-to-green, watery solution containing
bile salts, bile pigments (chiefly bilirubin, a breakdown product of hemoglobin), cholesterol,
phospholipids, and a variety of electrolytes. Of these components, only the bile salts (derived from
cholesterol) and phospholipids help the digestive process. Bile does not contain enzymes, but its bile
salts emulsify fats by physically breaking large fat globules into smaller ones, thus providing more
surface area for the fat-digesting enzymes to work on.
Functions of the Digestive System
The major functions of the digestive tract are usually summarized in two words—digestion and
absorption. However, many of its specific activities (such as smooth muscle activity) and certain
regulatory events are not really covered by either term. To describe digestive system processes a little
more accurately, we need to consider a few more functional terms. The essential activities of the GI
tract include the following six processes:
1. Ingestion. Food must be placed into the mouth before it can be acted on. This is an active, voluntary
process called ingestion.
2. Propulsion. To be processed by more than one digestive organ, foods must be propelled from one
organ to the next.
3. Food breakdown: Mechanical breakdown. --- Mechanical breakdown physically fragments food into
smaller particles, increasing surface area and preparing food for further degradation by enzymes.
4. Food breakdown: Digestion. The sequence of steps in which large food molecules are chemically
broken down to their building blocks by enzymes (protein molecules that act as catalysts) is called
digestion.
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5. Absorption. Absorption is the transport of digestive end products from the lumen of the GI tract to
the blood or lymph. For absorption to occur, the digested foods must first enter the mucosal cells by
active or passive transport processes. The small intestine is the major absorptive site.
6. Defecation. Defecation is the elimination of indigestible residues from the GI tract via the anus in the
form of feces.
Swallowing.
1. With the upper esophageal sphincter contracted,
the tongue pushes the food bolus posteriorly and
against the soft palate.
2. The soft palate rises to close off the nasal passages
as the bolus enters the pharynx. *** The larynx rises
so that the epiglottis covers its opening as peristalsis
carries the food through the pharynx and into the
esophagus. *** The upper esophageal sphincter
relaxes to allow food entry.
3. The upper esophageal sphincter contracts again as
the larynx and epiglottis return to their former
positions and peristalsis moves the food bolus
inferiorly to the stomach.
4. The cardioesophageal sphincter opens, and food
enters the stomach.
Mechanics of Swallowing.
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Peristaltic and segmental movements of the digestive tract.
(a) In peristalsis, adjacent or neighboring segments of the intestine (or other alimentary canal organs)
alternately contract and relax, thereby moving food distally along the tract.
(b) In segmentation, single segments of the intestine alternately contract and relax. Because active
segments are separated by inactive ones, the food is moved forward and then backward. Thus, the food
is mixed rather than simply propelled along the tract.
Peristaltic Waves in the Stomach
Once the food has been well mixed, a rippling peristalsis begins in the upper half of the stomach. (1) The
contractions increase in force as the food approaches the pyloric valve, grinding the food into chyme. ---
The pylorus of the stomach, which holds about 30 ml of chyme, acts like a meter that allows only liquids
and very small particles to pass through the pyloric sphincter. --- Because the pyloric sphincter barely
opens, each contraction of the stomach muscle squirts 3 ml or less of chyme into the small intestine. ---
(2) The contraction also closes the valve, so the rest of the chyme (about 27 ml) is propelled backward
into the stomach for more mixing, a process called retropulsion (3).
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Regulation of pancreatic juice and bile secretion and release.
The release of pancreatic juice into the duodenum is stimulated by both the vagus nerve and local
hormones. When chyme enters the small intestine, it stimulates the mucosa cells to produce several
hormones. Two of these hormones, secretin (se-kre′tin) and cholecystokinin (ko″le-sis″to-kin′in) (CCK),
influence the release of pancreatic juice and bile.
NUTRITION AND METABOLISM
Dietary Sources of the Major Nutrients
A nutrient is a substance in food that the body uses to promote normal growth, maintenance, and
repair. The nutrients divide neatly into six categories. The major nutrients—carbohydrates, lipids, and
proteins—make up the bulk of what we eat. Minor nutrients—vitamins and minerals. Water, which
accounts for about 60 percent of the volume of the food we eat, is also considered to be a major
nutrient.
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Metabolism (m˘e-tab′o-lizm; metabol = change) is a broad term referring to all chemical reactions that
are necessary to maintain life.
It involves catabolism (kah-tab′o-lizm), the breakdown of substances to simpler substances, and
anabolism, the building of larger molecules or structures from smaller ones.
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Carbohydrate Metabolism
The cells of the body use carbohydrates as their preferred fuel to produce cellular energy (ATP).
Glucose, also known as blood sugar, is the major breakdown product of carbohydrate digestion.
The three main metabolic pathways that are involved in cellular respiration.
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Fat Metabolism
The liver cells use some fats to make ATP for their own use; use some to synthesize lipoproteins,
thromboplastin (a clotting protein), and cholesterol; and then release the rest to the blood in the form
of relatively small fat-breakdown products.
Protein Metabolism
Proteins make up the bulk of cellular structures. Ingested proteins are broken down to amino acids ---
the building blocks of protein.
Metabolic roles of the liver
- Manufacturing bile
- Detoxification
- Remove amino acids, fatty acids, and glucose from the blood
- Remove and destroys bacteria that managed to get through the walls of the digestive tract to the
blood.
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- Help maintain the blood glucose level.
- Make glucose from non- carbohydrate substances (i.e., fats and proteins)
- Make cholesterol and secretes cholesterol by-products in bile.
- Synthesize non-essential amino acids.
Body Energy Balance
Energy intake = total energy output (heat + work + energy storage)
How is food intake controlled?
• Hypothalamus releases several peptides that influence feeding behavior.
• Body temperature and psychological factors
• Sensors in peripheral locations
When any fuel is burned, it consumes oxygen and liberates heat. The “burning” of food fuels by body
cells is no exception. Energy cannot be created or destroyed—it can only be converted from one form to
another. If we apply this principle to cellular metabolism, it means that a dynamic balance exists
between the body’s energy intake and its energy output.
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Basal Metabolic Rate
When nutrients are broken down to produce cellular energy (ATP), they yield different amounts of
energy - the energy value of food is measured in a unit called the kilocalorie (kcal). In general,
carbohydrates and proteins each yield 4 kcal/gram, and fats yield 9 kcal/ gram when they are broken
down for energy production.
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