Lympathic, Respiratory, Digestive

Describe the formation and movement of lymph through lymphatic vessels.

Formation: Lymph is formed when blood plasma leaks out of blood capillaries, becomes interstitial fluid (tissue fluid) surrounding cells, and then enters tiny lymphatic capillaries. 3L/day of fluid from plasma is filtered into lymphatic capillaries.

Movement: Interstitial → Lymphatic capillaries → Lymphatic Vessels → Lymphatic Trunks → Lymphatic Ducts → Blood vessels (veins)

Caught Von the Don

Different names of lymph as dependent on location

Lymph in lymph vessels, plasma in blood, and interstital fluid in tissues

The three major functions of the lymphatic system

Explain the role of B and T lymphocytes

T lymphocytes are cytotoxic. They attack cells (cancer, infected, and abnormal) directly. T cells use MHC molecules to ID & destroy an infected self cell. They provide a cellular immune response.

B lymphocytes differentiate in plasma cells and create antibodies. B cells provide a humoral immune response. Indirect attack.

They are both created in RBM but mature into different areas.

T cells=Thymus

B cells=RBM

Differentiate between primary lymphoid organs and secondary lymphoid organs

Primary organs=lymphocytes are created & created (RBM &Thymus)

Secondary=where immune responses take place (lymph nodes, spleen, lymph nodules, tonsils

Distinguish between humoral immunity and cell-mediated immunity

Cell-mediated immunity comes from T cells. Here, an antigen is recognized and bound. A small number of T cells grow and differentiate into a clone of effector cells. And then the antigen is eliminated. This is an adaptive immune defense response using macrophages to attack. Effective against: some cancer cells, foreign tissue transplants, intraceullar pathogens (virus, bacteria, fungi)

Humoral (antibody-mediated) immunity comes from B cells and is an adaptive immune response. Here, an antigen is found and bound, and helper T cells costimulate B cells, which differentiate into a clone of effector cells that produce antibodies. Effective against: extracellular pathogens in body’s fluid outside the cells

Identify the body’s first line of defense

An innate/non-specific immunity & the first of 2 lines of defense:

1. Mucous membranes

2. Skin

3. Antimicrobial secretions: lysozyme, sebum, gastric juice,

They are classified as physical & chemical barriers.

Describe the second line of defense

When microbes penetrate the skin and the mucous membranes, the next non-specific will be:

• Inflammation

• Fever

• Phagocytosis - (ingestion of microbes  neutrophils and macrophages)

• Natural killer cells (5-10% of lymphocytes)

• Antimicrobial proteins (AMPs)

  • Complement system activates about 30 proteins (mainly produced by the liver) that circulate in the blood and help the immune system destroy pathogens.

  • Interferons (if viral infection)

Explain the process of phagocytosis & inflammation

Phases of phagocytosis:

1. Chemotaxis (attraction)

2. Adherence

3. Ingestion

4. Digestion

5. Exocytosis

Inflammation = PRISH

1. P = pain

2. R = redness

3. I = immobility

4. S = swelling

5. H = heat

Define innate immunity and describe its characteristics

It is at birth and provides a general protection against invasion of a range of pathogens/antigens. Innate immunity involves barriers that keep harmful materials from entering your body. These barriers form the first line of defense in the immune response. It is two lines.

Define adaptive immunity and its properties: 

Adaptive immunity is a specialized, acquired immune response (using T and B lymphocytes) that develops over time after exposure to pathogens or vaccinations. The body system that carries out immune responses is the lymphatic system. It provides long-lasting, targeted protection against specific, non-self antigens through three key properties: high specificity for distinct pathogens, long-term memory of past infections, and precise self-recognition. Has both specificity and memory and is divided into 2 types: cell-mediated and antibody-mediated

• Specificity - The ability to distinguish between closely related, yet distinct, molecules and target specific antigens or pathogens. Antibodies act like a lock-and-key, binding only to specific antigens to render them harmless or trigger other immune cells.

• Memory - The immune system remembers antigens from previous exposures or vaccinations, allowing it to mount a faster and more vigorous response if the same pathogen reappears, often preventing re-infection.

• Self-recognition - The ability to differentiate between the body's own molecules ("self") and foreign substances ("non-self"), preventing the immune system from destroying its own tissues.

Distinguish between the right lymphatic duct and the thoracic duct.

The thoracic duct is much larger than the RLD and drains most of the lymph. The cisterna chyli is the inferiormost portion and is at the L1 & L2.

• Drains: lower extremities, pelvis, abdomen, left side of thorax, left upper extremity, and left of head and neck

• Empties: venous circulation at the junction of the left subclavian and left internal jugular veins

RLD

• Drains: most of upper quadrant of body, including RU trunk, RU extremeity, and R head and neck

• Empties: venous circulation at the junction of the right subclavian and right internal jugular veins

Define antigens and explain how they trigger immune responses.

Antigen = a chemical that binds to a lymphocyte receptor

Antigens are substances recognized as foreign that provoke an immune responses

How Antigens Trigger Immune Responses

• Recognition as "Non-Self": Immune cells constantly check cells for self-markers. Antigens on foreign entities (bacteria, viruses) or abnormal body cells (cancer) lack these markers, marking them for attack.

• Antibody Production (Adaptive Immunity): B cells detect antigens and produce specific Y-shaped antibodies tailored to fit the antigen like a "lock and key".

• Binding and Neutralization: Antibodies bind to epitopes (surface features of the antigen), which can neutralize toxins, block viruses from entering cells, or cause pathogens to clump together (agglutination).

• Immune System Activation: Once bound, antigens signal other immune components—such as complement proteins or phagocytes (like macrophages)—to destroy the invader.

Explain the three major functions of the lymphatic system:

• Returning excess fluid to the cardiovascular system (Fluid balance) and return of interstitial fluid to the bloodstream

• Transporting dietary lipids absorbed by GI tract to blood [fatty lymph is called chyle] (Absorption of dietary lipids from the digestive tract)

• Facilitates immune responses/gives immunity to diseases & fights infections (Immune defense)

Describe the structure & function of lymph nodes

Stops lymph flow to start filtration, cleaning the lymph of pathogens. It is bean-shaped. There are about 500 of them. The superficial ones include inguinal, cervical, and axillary; deep ones include: thorax, abdomen, pelvis. It is surrounded by a fibrous capsule (dense connective tissue) and the fibrous strands extend inward and divide the node into compartments.

Lymph enters the convex of nodes: afferent lymph vessels

Lymph exits from the hilum of nodes: efferent lymph vessels

Describe the structure and function of the spleen

The spleen is the largest lymphatic organ. It has two regions that filter blood

1. White pulp: lymphocytes and macrophages carry out immune function

2. Red pulp: removes dead blood cells and platelets

Describe the structure and function of the thymus

It is a primary lymphatic organ. Unlike other lymphoid organs, it is not made of MALT. Site of maturation for T cells, most are created during adolescence. Only about 2% develop and move from the cortex to the medulla. After puberty, it atrophies. It is selective about what T cells mature.

Describe the structure and function of the tonsils

A secondary lymphatic organ. They are swellings of the mucosa lining the pharynx. There are 4 groups:

1. Palatine (largest and often infected)

2. Lingual (under tongue)

3. Tubal (below pharyngeal and above palatine)

4. Pharyngeal (aka adenoid)

The four groups are arranged in a ring around the entrance to the pharynx to gather and remove many pathogens that enter the pharynx in inspired air and swallowed food.

Important immune cells

Cytotoxic T cells - 1 of 3 specialized T cells. Directly kills infected, cancerous, transplanted tissue or abnormal cells. Involved in cell-mediated immunity.

Helper T cells - 1 of 3 specialized T cells. When stimulated by specific antigens, helper T cells help activate and clone B cells and cytotoxic T cells. Involved in cell-mediated immunity.

Plasma cells - 1 of 2 specialized B cells. Secretes antibodies, and involved in anti-mediated immunity.

Explain the difference between active and passive immunity

Active immunity involves the body producing its own antibodies and memory cells after natural infection or vaccination, providing long-lasting protection.

Passive immunity is the short-term protection gained by receiving pre-made antibodies from another source (e.g., mother to fetus, or antibody injections), offering immediate but temporary immunity

Gaining immunocompetence naturally or artificially.

Natural:

• Active: getting sick and making T and B clones to fight it of better next time

• Passive: baby getting antibodies through placenta

Artifical:

• Active: Getting vaccinated, make T and B clones to fight it off better next time

• Passive: Injection of antibodies (temporary solution)

Describe how antibodies are produced and how they function.

Plasma cells create antibodies and they function as a protein component of the immune system that circulates in the blood, recognizes foreign substances like bacteria and viruses, the antibodies then mark these antigens for destruction.

Explain the anatomy and function of lymphatic capillaries, collecting vessels, trunks, and ducts

Function: Lymphatic capillaries function as highly permeable vessels that collect excess fluid from interstitial spaces and are located near blood vessels. It contains a one-way flow of lymph - from periphery toward heart.

Anatomy: Walls are a single layer of endothelial cells, and permeability comes from arrangement of those endothelial cells (few intercellular junctions and edges of nearby cells overlap → minivalves [easily opened]). High permeabilty allows any bacteria, viruses, or cancer cells to enter easily → lymph nodes destroying them

Explain the anatomy and function of collecting vessels

Anatomy: Formed by merging capillaries; Formed by merging capillaries; they resemble blood vessels but much thinner walls leading to low pressure, and more valves to prevent to direct flow of lymph. At base of valve, it bulges equaling pockets of collected lymph that closes the valve, and it resembles a string of beads. Unique appearance lets it be recognizable in X-rays after injection with radiopaque dye.

Function: Transport lymph from capillaries towards the lymph nodes, filtered, then moved further toward the body's trunk.

Explain the anatomy and function of trunks

Anatomy: Formed from lymph vessels. Paired (mostly) or single trunks named for the regions they drain: Lumbar, intestinal (unpaired), bronchomediastinal, subclavian, and jugular trunks.

Function: drain large areas of the body. Drainage from specific trunks: Lumbar trunks drain lower limbs and pelvic organs, Intestinal trunk receive chyle from stomach and intestines, Bronchomediastinal trunks receive lymph from the thoracic organs and wall, Subclavian trunks receive lymph from the upper limb and superior thoracic wall, and Jugular trunks drain the head and neck

Explain the anatomy and function of ducts

• Anatomy: Two main channels in the chest that receive lymph from trunks: the Right Lymphatic Duct (small) and the Thoracic Duct (large). The thoracic duct has the cisterna chyli located as L1 and L2.

• Function: Drain into the venous circulation at the subclavian veins (returning fluid to blood).

  • Right Lymphatic Duct: Drains the upper right quadrant of the body (right head, arm, thorax).

  • Thoracic Duct: Drains the rest of the body (lower body, left side of the head, neck, chest, and left arm).

Distinguish between immunodeficiency, autoimmunity, and hypersensitivity.

Immunodeficiency, autoimmunity, and hypersensitivity represent distinct dysfunctions of the immune system: immunodeficiency = underactive response, autoimmunity = misdirected response against self-tissue, and hypersensitivity = overactive response to antigens

Identify the major lymphatic organs and tissues and their functions.

The major lymphatic organs and tissues—bone marrow, thymus, lymph nodes, spleen, and MALT like tonsils—produce, mature, and house T and B cells. They function as the body's primary immune surveillance network by filtering pathogens and damaged cells from lymph and blood while managing fluid balance.

Primary Lymphatic Organs: RBM that produces lymphocytes and all other blood cells. It is the site of B cell maturation. Thymus: Located in the upper chest, this organ is crucial for T cell maturation, particularly during childhood before it shrinks after puberty.

Secondary Lymphatic Organs and Tissues: These sites filter pathogens and initiate immune responses.

• Lymph Nodes: Over 500 bean-shaped glands filter lymph fluid as it passes through the body, removing bacteria and waste.

• Spleen: Located in the upper left abdomen, this organ filters blood rather than lymph. It breaks down old red blood cells and acts as a major hub for immune cells.

• Tonsils and Adenoids: Located in the pharynx, these tissues trap pathogens from food and inhaled air.

• Mucosa-Associated Lymphoid Tissue (MALT): Including Peyer's patches in the intestines and the appendix, this tissue protects vulnerable mucous membranes from infection.

Describe the effects of allergies and hypersensitivity reactions.

Allergies and hypersensitivity reactions are excessive immune responses to harmless substances (allergens), causing inflammation, tissue damage, and symptoms ranging from mild (sneezing, hives) to life-threatening. Upon exposure, the immune system releases mediators like histamine, leading to vascular dilation, itching, edema, and constricted airways

Identify the major structures of the lymphatic system including lymphatic vessels, lymph nodes, spleen, thymus, tonsils, and lymph.

The lymphatic system is a vital part of the immune and circulatory systems, composed of a network of lymphatic vessels transporting lymph through bean-shaped lymph nodes. Major structures include the spleen (filters blood), thymus (matures T-cells), tonsils (defend against ingested/inhaled pathogens), and bone marrow.

• Lymph: A clear-to-white fluid containing lymphocytes that circulates throughout the system to remove bacteria and proteins from tissues.

• Lymphatic Vessels: A network of thin-walled tubes (capillaries, vessels, and ducts) that transport lymph throughout the body. They contain valves to prevent backflow and return fluid to the venous system.

• Lymph Nodes: Bean-shaped structures found along vessels that act as filters, trapping pathogens, foreign particles, and cancer cells. There are around 600 in the body, often found in clusters (neck, armpits, groin).

• Spleen: It is the largest lymphatic organ. It filters blood, removes old red blood cells, and stores lymphocytes to fight infection.

• Thymus: It is most active before puberty and acts as the maturation site for T-cells.

• Tonsils: Lymphoid tissue located in the pharynx (throat) that acts as the first line of defense against ingested or inhaled pathogens.

Explain causes and mechanisms of autoimmune diseases such as: Graves’ disease & Celiac disease

Autoimmune diseases, such as Graves’ disease and Celiac disease, occur when the immune system mistakenly attacks healthy cells, driven by genetic susceptibility and environmental triggers. Graves’ disease involves antibodies overstimulating the thyroid (hyperthyroidism), while Celiac disease involves an immune reaction to gluten that damages the small intestine

Distinguish between: Upper respiratory tract and Lower respiratory tract

Upper respiratory tract: nose, pharynx, & associated structures

Lower respiratory tract: larynx, trachea, bronchi, & lungs

Respiratory control centers in the brain

medullary respiratory center in the medulla oblongata and pontine resporatory group in the pons

Explain the process of inhalation (inspiration)

Inhalation: volume of lungs expands (& pressure decreases) and air flows in.

Inhalation (inspiration) is the active process of breathing in, where the diaphragm and external intercostal muscles contract, expanding the thoracic cavity. This increase in volume → lowers internal pressure below atmospheric pressure, forcing air into the lungs. This essential, energy-requiring mechanism acts to bring oxygen into the body, generally taking about 1 second to complete.

Explain the process of exhalation (expiration)

Exhalation: volume of lungs decreases (& pressure increases) and air rushes out.

Exhalation (or expiration) is the passive process during quiet breathing (not during forceful breathing) of releasing air from the lungs, driven by the relaxation of the diaphragm and internal intercostal muscles. This relaxation reduces the thoracic cavity volume, increases lung pressure (Boyle’s law), and forces oxygen-rich air out. It acts as a mechanism for breathing in sleep, speaking, singing, and blowing out candles.

Understand diffusion and partial pressure gradients (Dalton’s Law)

States: Each gas in a mixture of gases exerts its own pressure as if no other gases were present. It assumes each gas acts independently, with its pressure depending on its amount and volume, not its identity. Diffusion drives gases from high to low partial pressure, regulating respiration as gases move down these pressure gradients across membranes

The exchange of oxygen and carbon dioxide between alveolar air and pulmonary blood occurs via passive diffusion, which is governed by the behavior of gases as described by two gas laws, Dalton’s law and Henry’s law. Dalton’s law is important for understanding how gases move down their pressure gradients by diffusion

Henry's Law (dissolution of gases in liquids)

States: The quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility coefficient when the temperature remains constant

Henry's Law states that the amount of dissolved gas in a liquid is directly proportional to its partial pressure above the liquid at a constant temperature

The exchange of oxygen and carbon dioxide between alveolar air and pulmonary blood occurs via passive diffusion, which is governed by the behavior of gases as described by two gas laws, Dalton’s law and Henry’s law. Henry’s law helps explain how the solubility of a gas relates to its diffusion

Carbon dioxide is transported as what?

• Bicarbonate ions (HCO₃⁻) – majority

• Bound to hemoglobin (carbaminohemoglobin)

• Dissolved in plasma

Oxygen is transported as what?

• Binding to Hemoglobin (carried by Hb) - majority

• Oxyhemoglobin formation (dissolves in the plasma)

Explain external respiration (lungs ↔ blood)

External respiration is the exchange of gases (oxygen and carbon dioxide) between the alveoli of the lungs and the blood within pulmonary capillaries. It is a passive, diffusion-based process where oxygen enters the blood and carbon dioxide leaves it to be exhaled, occurring in the lungs to oxygenate blood.

During external respiration, oxygen will diffuse from the alveoli into the pulmonary capillaries

Explain internal respiration (blood ↔ tissues)

Internal respiration is the exchange of gases (oxygen and carbon dioxide) between the bloodstream and the body’s tissue cells. It is a diffusion process driven by partial pressure gradients, where oxygen moves from blood to tissues and carbon dioxide moves from cells to blood.

During internal respiration, oxygen will diffuse from the systemic capillaries into the tissue

Interpret and define all the lung volumes

Tidal volume (VT) - While at rest, a healthy adult averages 12 breaths a minute, with each inhalation and exhalation moving about 500 mL of air into and out of the lungs. The volume of one breath is called the tidal volume (VT) - varies considerably from one person to another and in the same person at different times

Inspiratory reserve volume - By taking a very deep breath, you can inhale a good deal more than 500 mL, This is the additional inhaled air.

Expiratory reserve volume - If you inhale normally and then exhale as forcibly as possible, you should be able to push out considerably more air in addition to the 500 mL of tidal volume

Residual volume (RV) - cannot be measured. remains even after all breath able to be is exhaled. Even after the expiratory reserve volume is exhaled, considerable air remains in the lungs because the subatmospheric intrapleural pressure keeps the alveoli slightly inflated, and some air remains in the noncollapsible airways.

Calculate lung capacities

Inspiratory Capacity (IC) = tidal volume (VT) + Inspiratory reserve volume (IRV)

Functional Residual Capacity (FRC) = residual volume + expiratory reserve volume (ERV)

Vital Capacity (VC) = inspiratory reserve volume (IRV) + tidal volume (VT) + expiratory reserve volume (ERV)

Total Lung Capacity (TLC) = vital capacity (VC) + residual volume

Identify layers of the respiratory membrane

Alveolar epithelium - A layer of type I and type II alveolar cells and associated alveolar macrophages that constitutes the alveolar wall

Basement membrane - An epithelial basement membrane underlying the alveolar wall & A capillary basement membrane that is often fused to the epithelial basement membrane

Capillary endothelium

Name and function of alveolar cells

Type I cells - Simple squamous epithelium that forms a continuous lining

Type II (septal cells) - Secrete fluid with surfactant that prevents collapse of alveoli during exhalation by reducing the surface tension

Macrophages - Eat small dust particles and debris

Identify the organs of the respiratory system

Nose and nasal cavity, pharynx, larynx, trachea, bronchi and bronchioles, lung, alveoli

Function and anatomy of nose

Anatomy: The external portion of the nose is made of hyaline cartilage and lined with mucous membrane. The bony portion features frontal, nasal, and maxillary bones.

Function: Airway for respiration, moistens and warms air, filters air, resonating chamber for speech

Function and anatomy of nasal cavity

Anatomy: External nares = nares. Divided by septum. Is continuous with nasopharynx. Posterior nasal aperture - conchae that increases surface tension. Has two types of mucous membranes: Olfactory mucosa (near roof of nasal cavity) and respiratory mucosa (lines nasal cavity and the epithelium is pseudostratified ciliated columnar). Has a root, apex, bridge, and nostril

Function: The olfactory mucosa houses olfactory receptors

Paranasal sinuses are located in..

Frontal bone

Ethmoid bone

Maxillary bones

Spehnoid bone

Function and anatomy of pharynx

Anatomy: Has 3 regions: nasopharynx (air passageway), oropharynx (air passage and swallowed food), laryngopharynx (continuous with esophagous and larnyx)

Function: passageway for food and air, resonating chamber for speech sounds, and houses the tonsils

Function and anatomy of larynx

Anatomy - Made of several pieces of cartilage: epiglottis (elastic cartilage, closes when swallowing), thyroid cartilage (Adam’s apple), arytenoid cartilage (paired), cricoid cartilage (landmark for surgery)

Function - Voice production (has vocal folds that vibrate), provides open airway, routes air and food into the proper channels

Function and anatomy of trachea

Extends from larynx to primary bronchi, tubular passageway about 5 inches long, 16-20 pieces of C-shaped cartilage (hyaline) provide structure and keep airways patent 

Function and anatomy of bronchi and bronchioles

Anatomy: Carina marks division of trachea where right main bronchus enter right lung and the left main bronchus enters the left lung.

Changes from pseudostratified ciliated columnar → simple columnar → simple cuboidal

Changes from cartilage to smooth muscle

Function and anatomy of lungs

Anatomy: Pleural membrane: pleural cavity with flud between visceral pleura and parietal pleura. Apex=superior & base=inferior.

Each lobe recieves a secondary bronchus. The hilum is a doorway for bronchi, blood vessels, lymphatic vessels, and nerves

Right lung has 3 lobes and is seperated by fissures

Left lung has 2 lobes and is smaller.

Mechanisms of Pulmonary Ventilation, describing roles of the diaphragm, external intercostal muscles, internal intercostal muscles

Inhalation (quiet breathing): 75% diaphragm + 25% external intercostals

Exhalation (quiet breathing): passive process

Inhalation (forceful breathing): Above + accessory muscles

Exhalation (forceful exhalation): Internal intercostals + abdominal muscles

Branching of bronchial tree

Main (primary) bronchi → lobar (secondary) bronchi → segmental (tertiary) bronchi → bronchioles → terminal bronchioles

Conducting vs Respiratory Zone

Conducting zone: Nose → nasal cavity → pharynx → larynx → trachea → bronchial tree

Respiratory Zone: Respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli

Anatomy and function of alveoli

Anatomy: Has 2 types of cells and has macrophages. Alveolus = cup-shaped pouch stemming from alveolar duct. Alveolar sac = group of 2 or more alveoli ith a shared duct (bunch of grapes)

Function: Type I cells - Simple squamous epithelium that forms a continuous lining and Type II (septal cells) - Secrete fluid with surfactant that prevents collapse of alveoli during exhalation by reducing the surface tension. Alveolus is the site of gas exchange

Name and function of stomach cells

Parietal cells - HCl (activates pepsin, kills bacteria, denatures proteins)

G cells - gastrin

Chief - pepsinogen

Mucous - mucus

Regions of stomach

Cardia, body, fundus, pylorus

Functions of stomach

Storage, churning, protein digestion

Parts of alimentary canal

mouth, pharynx, esophagus, stomach, small intestine, large intestine

accessory organs of digestive system

teeth, tongue, salivary gland, liver, gallbladder, pancreas

Processes of the digestive system

Ingestion → taking in food

Secretion → enzymes, acid, bile, mucus

Motility → peristalsis, segmentation

Digestion → mechancial: chewing, churning; chemical: enzymes

Absorption → nutrients into blood/lymph

Defecation → waste removal

Layers and parts of the GI tract/alimentary canal

Mucosa - epithelium (stratified squamous everywhere but stomach and intestines where it is simple columnar), lamina propria, muscularis mucosae

Submucosa - blood vessels, submucosal plexus

Muscular layer - circular layer, longitudinal layer, myenteric plexus (+oblique layer in stomach)

Serosa/Adventita

Functions of the liver

Produces bile, detoxifies, stores glycogen & vitamin

Functions of gallbladder

Stores and concentrates bile, releases bile (fat digestion)

Enzymes of pancreas

Amylase → carbs

Lipase → fats

Proteases → proteins

Bicarbonate → neutralizes acid

Why is bile important?

It is not an enzyme but it emulsifies fats and increases surface area for lipase

Where is the main site for digestion & absorption?

Small intestine

Sections of small intestine

Duodenum, jejunum, ileum

What increases the the surface of the small intestine?

Circular folds, villi, microvilli

Where does the molecules absorbed from the small intestine go?

Carbs → glucose → blood

Proteins → amino acids → blood

Fats → fatty acids → lymph (lacteals)

Functions of small intestine

Absorbs water & electrolytes and forms feces

Which bacterias are in the large intestine?

Vitamin K and B

Sections of large intestine

Cecum, colon (ascending, transverse, descending, sigmoid), rectum, analx canal

Anatomy of the large intestine

Haustra & teniae coli

Defecation reflex steps

1. Stress of rectum triggers reflex

2. Internal anal sphincter → involuntary

3. External anal sphincter → voluntary

The three salivary glands

Parotid, sublingual, submaxillary

Two pathways of digestion for mouth & saliva

Chemical → begins

1. Salivary amylase → starch → maltose

2. Lingual lipase (activated later)

Mechanical → chewing

How does the esophagus move food?

By peristalsis

Sphincters of the esophagus

Lower esophageal spincter: esophagus → stomach

Upper esophageal sphincter: pharynx → esophagus

The weakening of which esophageal sphincter trigger GERD?

A weak lower esophageal sphincter

Which part of the alimentary canal has a adventitia, not a serosa?

Esophagus

Phases of swallowing (+fact about epiglottis)

1. Buccal phase → voluntary

2. Pharyngeal phase → involuntary

3. Esophageal phase → peristalsis

Epiglottis prevents choking by closing over the larynx when swallowing, pushing food towards the esophagus

Clinical conditions of the digestive system and their causes

Ulcers → H. pylori/excess acid

GERD → acid reflex/weak LES

Gallstones → bile blockage

Hepatitis → liver inflammation

Pancreatitis → enzyme activation

Lactose intolerance → lactose deficiency

Hormones for Regulation

• Gastrin → increases HCl production

• Secretin (secreted by small intestine) → increases bicarbonate

• CCK (secreted by small intestine) → increases pancreatic enzymes and bile release

Enzyme Regulation

• Amylase → carbs

• Pepsin → proteins

• Trypsin (pancreas) → proteins

• Lipase → fats

Two plexus of the enteric nervous system and their functions

Myenteric plexus → motility

Submucosal plexus → secretion

Descibe gas exchange at the alveoli

The exchange of oxygen and carbon dioxide between alveolar air and pulmonary blood occurs via passive diffusion.

• Oxygen moves from the alveoli into the blood by diffusion, going from an area of higher concentration (in the alveoli) to lower concentration (in the blood).

• At the same time, carbon dioxide moves from the blood into the alveoli, where its concentration is lower.

Gas exchange between air and blood

Gas exchange occurs between the air in the alveoli and the blood in surrounding capillaries. Oxygen diffuses from the alveoli (high O₂ concentration) into the blood (low O₂ concentration). Carbon dioxide diffuses from the blood (high CO₂ concentration) into the alveoli (low CO₂ concentration). This exchange happens by diffusion across very thin alveolar and capillary walls

Oxygen enters red blood cells and binds to hemoglobin for transport. Carbon dioxide moves into the alveoli and is removed during exhalation

Transport of respiratory gases (oxygen and carbon dioxide)

The cardiovascular system assists the respiratory system by transporting gases.

Respiratory gases (oxygen and carbon dioxide) are transported between the lungs and tissues via the blood, driven by partial pressure differences. Oxygen is mainly transported bound to hemoglobin in red blood cells. Carbon dioxide travels as bicarbonate ions, carbaminohemoglobin, and dissolved in plasma

Pulmonary ventilaiton (movement of air in and out of lungs)

In pulmonary ventilation, air flows between the atmosphere and the alveoli of the lungs because of alternating pressure differences created by contraction and relaxation of respiratory muscles: Inhalation & exhalation)

Affected by: surface tension of alveolar fluid (lack of surfectant), compliance of lungs, and airway resistance

Common respiratory disorders

• COPD & asthma - increases airway resistance due to obstruction or collapse of the airways

• Asthma - Major abnormality is constriction of airways due to spasms of smooth muscle in bronchial tubes. Treatment: Bronchodilators and anti-inflammatory corticosteroids

• Emphysema - a progressive, chronic lung disease (a type of COPD) causing shortness of breath, cough, and wheezing due to damage to the air sacs (alveoli). Primarily caused by smoking and environmental toxins, it reduces lung elasticity and traps air.

• Pneumonia - an infection that inflames the air sacs (alveoli) in one or both lungs, causing them to fill with fluid or pus

• Tuberculosis - a contagious infection caused by Mycobacterium tuberculosis bacteria, typically attacking the lungs