Immune Response System

Innate Immunity

Innate immunity is the body's first line of defense against pathogens, providing rapid, non-specific protection. It includes physical barriers, cellular defenses, and chemical mediators.

• Major Parts: Skin and mucous membranes (physical barriers), phagocytic cells, natural killer cells, inflammation, complement system, and interferons.

• First Line of Defense: Physical and chemical barriers such as skin and mucous membranes; these prevent pathogen entry.

• Interferons: Proteins (notably alpha and beta interferons) released by virus-infected cells to inhibit viral replication and activate immune cells.

• Complement System: A group of plasma proteins that enhance phagocytosis, lyse pathogens, and stimulate inflammation; interacts with adaptive immunity by marking pathogens for destruction.

• Inflammation: Triggered by tissue injury or infection; increases blood flow, recruits immune cells, and promotes healing.

• Natural Killer Cells (NKC): Target and destroy virus-infected and cancerous cells by inducing apoptosis.

• Phagocytosis: Performed by neutrophils and macrophages; these cells engulf and digest pathogens.

Adaptive Immunity

Adaptive immunity is specific and involves memory, allowing for a stronger response upon re-exposure to the same pathogen.

• Advantages: Specificity, memory, and ability to tailor responses.

• Disadvantages: Slower initial response, potential for autoimmunity.

B-Cells

B-cells are lymphocytes responsible for humoral immunity, producing antibodies against extracellular pathogens.

• Activation: Requires antigen binding and co-stimulation from helper T-cells.

• Clonal Expansion: Activated B-cells proliferate to form clones.

• Differentiation: Clones become plasma cells (antibody producers) or memory B-cells.

• Antibodies: Attack pathogens in extracellular spaces.

• Co-stimulation: Interaction with helper T-cells enhances activation.

T-Cells

T-cells mediate cellular immunity, targeting infected or abnormal cells.

• Types: Helper T-cells (CD4+), cytotoxic T-cells (CD8+), regulatory T-cells.

• Functions: Helper T-cells activate other immune cells; cytotoxic T-cells kill infected cells; regulatory T-cells modulate immune response.

Vaccines

Vaccines expose the immune system to antigens, stimulating memory cell formation without causing disease.

• Basis: Induce adaptive immunity and immunological memory.

Antigens and Haptens

An antigen is a molecule recognized by the immune system as foreign, triggering a response. Haptens are small molecules that become antigenic only when attached to larger carriers.

• Function: Stimulate antibody production.

• Difference: Haptens alone do not elicit a response; antigens do.

Maturation of B and T Cells

B and T cells undergo maturation to become immunocompetent, capable of recognizing antigens.

• Positive Selection: Ensures cells recognize self-MHC.

• Negative Selection: Eliminates self-reactive cells.

• Location: B-cells mature in bone marrow; T-cells in thymus.

Immunoglobulins (Antibodies)

Immunoglobulins are proteins produced by plasma cells, each with a specific structure and function.

• Basic Structure: Y-shaped molecule with variable and constant regions.

• Types: IgG, IgA, IgM, IgE, IgD; each associated with different immune functions.

Definitions

• Immunocompetence: Ability of a cell to mount an immune response.

• MHC I: Present on all nucleated cells; presents endogenous antigens to CD8+ T-cells.

• MHC II: Present on antigen-presenting cells; presents exogenous antigens to CD4+ T-cells.

Cytokines

Cytokines are signaling proteins that regulate immune responses.

• Roles: Stimulate cell growth, differentiation, and activation.

Respiratory System

Functions

The respiratory system exchanges gases, regulates blood pH, and enables voice production.

• Voice Production: Pitch and loudness controlled by tension and force of air over vocal cords.

Functional Anatomy

• Nasal Cavity: Warms, humidifies, and filters air; lined with mucous membranes.

• Mucous Membranes: Trap particles, moisten air, and contain immune cells.

Structure

• Larynx: Contains vocal cords; maintains open airway.

• Trachea: Supported by cartilage rings; keeps airway patent (open).

• Bronchi/Bronchioles: Cartilage replaced by smooth muscle in smaller bronchioles; patency maintained by muscle tone.

• Alveoli: Site of gas exchange; cell types include Type I (gas exchange), Type II (surfactant production), and macrophages (defense).

• Shared Basement Membrane: Facilitates rapid diffusion of gases.

• Surfactant: Reduces surface tension, preventing alveolar collapse.

Pressures in Ventilation

• Atmospheric Pressure: Pressure of air outside the body.

• Intrapulmonary Pressure: Pressure within alveoli.

• Intrapleural Pressure: Pressure within pleural cavity; always negative relative to alveoli.

• Transpulmonary Pressure: Difference between intrapulmonary and intrapleural pressures; keeps lungs inflated.

Gas Laws

• Boyle's Law: (Pressure and volume are inversely related; governs ventilation.)

• Dalton's Law: (Total pressure is sum of partial pressures; explains gas exchange.)

• Charles's Law: (Volume and temperature are directly related; affects gas transport.)

Haldane Effect

The Haldane effect describes how oxygenation of blood decreases its capacity to carry carbon dioxide.

• Application: Important for CO2 transport in plasma.

Gas Transport

• Oxygen: Mostly bound to hemoglobin in red blood cells; small amount dissolved in plasma.

• Carbon Dioxide: Transported as dissolved gas, carbaminohemoglobin, and bicarbonate ion.

• Bicarbonate Formation:

Ventilation-Perfusion Coupling

Matching of air flow (ventilation) and blood flow (perfusion) in the lungs for optimal gas exchange.

• Factors: Local oxygen and carbon dioxide levels, smooth muscle tone.

Definitions

• Pulmonary Ventilation: Movement of air in and out of lungs; includes inspiration and expiration.

• External Respiration: Gas exchange between alveoli and blood.

• Internal Respiration: Gas exchange between blood and tissues.

• Gas Transport: Movement of gases in blood; relates to oxyhemoglobin dissociation curve.

Oxyhemoglobin Curve

Shows relationship between oxygen saturation and partial pressure; affected by pH, CO2, temperature.

• Loading/Unloading: Increased CO2 or temperature shifts curve right (more unloading).

Spirometer Volumes

• Capacities: Calculated by adding volumes (e.g., vital capacity = tidal + inspiratory + expiratory reserve).

Control of Breathing

• Brain Centers: Medulla oblongata and pons.

• Stimulus: Increased CO2 and H+ levels stimulate increased rate and depth.

Digestive System

Parts of GI System

• Alimentary (GI) Tract: Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus.

• Accessory Organs: Salivary glands, liver, gallbladder, pancreas.

Digestive Processes

• Ingestion: Taking food into the mouth.

• Movement: Propulsion of food through GI tract.

• Mechanical Breakdown: Physical breakdown (chewing, churning).

• Digestion: Chemical breakdown by enzymes.

• Absorption: Uptake of nutrients; most occurs in small intestine.

• Stomach/Large Intestine Absorption: Water, electrolytes, some drugs.

Bile and Fat Digestion

• Role: Emulsifies fats for enzyme action.

• Production: Liver produces bile.

• Storage: Gallbladder concentrates and stores bile.

Peritonitis

• Definition: Inflammation of peritoneum.

• Major Cause: Infection from ruptured abdominal organs.

Stomach Anatomy

• Gross: Regions include cardia, fundus, body, pylorus.

• Microscopic: Gastric glands produce gastric juice (HCl, pepsinogen, mucus).

• Cells: Parietal (HCl), chief (pepsinogen), mucous (mucus).

• Stimulus: Vagus nerve, gastrin hormone.

Sphincters/Valves

• Definition: Muscular rings controlling passage of food.

Digestive Hormones

Peritoneal vs Mesentery Tissues

• Peritoneal: Serous membrane lining abdominal cavity.

• Mesentery: Double layer of peritoneum supporting intestines.

Histology of Alimentary Organs

• Layers: Mucosa, submucosa, muscularis, serosa.

Tooth Structure

• Impact Bearing: Enamel bears most chewing impact.

Mucosa Absorptive Vessels

• Capillaries: Absorb amino acids and sugars.

• Lacteals: Absorb fats.

Small Intestine Surface Area

• Modifications: Villi, microvilli, and folds increase absorption.

Salivary Glands

• Types: Parotid, submandibular, sublingual.

• Production: About 1-1.5 liters/day; saliva contains amylase, mucus.

• Function: Lubricates, begins starch digestion.

Bolus and Chyme

• Bolus: Formed in mouth; mass of chewed food.

• Chyme: Formed in stomach; semi-liquid food.

Motility

• Peristalsis: Propels food; occurs throughout GI tract.

• Segmentation: Mixes food; mainly in small intestine.

• Churning: Occurs in stomach.

Major Enzymes

Vitamins

• Water Soluble: B, C vitamins; absorbed directly.

• Fat Soluble: A, D, E, K; require bile for absorption.

• Intestinal Bacteria: Produce vitamin K.

Tongue Papillae

• Types: Filiform, fungiform, circumvallate, foliate.

• Taste Buds: Not all papillae have taste buds; filiform do not.

• Function: Taste, texture, manipulation of food.

Stomach Phases

• Cephalic: Triggered by sight/smell of food; stimulates gastric secretion.

• Gastric: Triggered by food in stomach; increases secretion and motility.

• Intestinal: Triggered by chyme in intestine; inhibits gastric activity.

Gastric Functions

• Motility: Stimulated by distension and gastrin.

• Secretion: Stimulated by vagus nerve and gastrin.

• Emptying: Regulated by duodenal feedback.

Enterohepatic Circulation

• Definition: Recycling of bile salts from intestine to liver.

Hepatic Portal Circulation

• Definition: Blood from GI tract passes through liver for processing before entering systemic circulation.