BIO 204 Exam 2: Lymphatic, Immune, and Respiratory Systems Study Guide

Lymphatic System

Lymphatic Organs and Their Functions

• Lymph Nodes: Small, bean-shaped structures that filter lymph and house lymphocytes. They trap pathogens and present them to immune cells for destruction.

• Spleen: The largest lymphatic organ; filters blood, removes old erythrocytes, and mounts immune responses to blood-borne antigens.

• Thymus: Site of T lymphocyte maturation; most active during childhood and atrophies with age.

• Red Bone Marrow: Primary site of hematopoiesis (formation of blood cells), including lymphocytes.

Lymph Node Anatomy

• Cortex: Contains follicles with germinal centers rich in B cells.

• Medulla: Contains medullary cords with T cells, B cells, and plasma cells.

• Afferent Vessels: Bring lymph into the node.

• Efferent Vessels: Carry filtered lymph away from the node.

Lymphatic Trunks and Ducts

• Lymphatic Trunks: Large vessels that drain lymph from regions of the body (e.g., jugular, subclavian, bronchomediastinal, lumbar, intestinal).

• Lymphatic Ducts: The right lymphatic duct drains the right upper body; the thoracic duct drains the rest of the body into the venous system.

Consequences of Lymph Node Removal

• Can lead to lymphedema (swelling due to lymph accumulation) and increased risk of infection in the affected area.

Immune System

Cells of Innate Immunity and Their Functions

• Neutrophils: Most abundant leukocytes; phagocytose bacteria and release antimicrobial substances.

• Macrophages: Engulf pathogens and dead cells; present antigens to T cells.

• Dendritic Cells: Antigen-presenting cells that activate T cells.

• Natural Killer (NK) Cells: Destroy virus-infected and cancerous cells by releasing perforins.

• Mast Cells: Release histamine and other mediators during inflammation and allergic responses.

Cells of Adaptive Immunity and Their Functions

• B Lymphocytes (B cells): Produce antibodies (humoral immunity).

• T Lymphocytes (T cells): Include helper T cells (activate other immune cells) and cytotoxic T cells (destroy infected cells; cellular immunity).

Lymphocytes

• White blood cells central to adaptive immunity; include B cells, T cells, and NK cells.

Major Histocompatibility Complexes (MHC) and Their Purpose

• MHC I: Present on all nucleated cells; present endogenous antigens to cytotoxic T cells.

• MHC II: Present on antigen-presenting cells; present exogenous antigens to helper T cells.

Complement Proteins and the Complement System (3 Pathways)

• Classical Pathway: Triggered by antibodies bound to antigens.

• Lectin Pathway: Initiated by lectin binding to pathogen carbohydrates.

• Alternative Pathway: Activated directly by pathogen surfaces.

• All pathways converge to form the membrane attack complex (MAC), leading to cell lysis.

Primary vs. Secondary Immune Response

• Primary Response: First exposure to antigen; slower, lower antibody production.

• Secondary Response: Subsequent exposures; faster and stronger due to memory cells.

Mast Cell Activation and Sensitization

• Mast cells bind IgE antibodies during sensitization; upon re-exposure to antigen, they degranulate, releasing histamine and other mediators.

Classes of Immunoglobulins/Antibodies

Class	Main Function
IgG	Main antibody in blood; crosses placenta
IgA	Found in secretions (tears, saliva, mucus)
IgM	First antibody produced in response
IgE	Involved in allergic reactions
IgD	Functions mainly as B cell receptor

Humoral vs. Cellular Immunity

• Humoral Immunity: Mediated by B cells and antibodies; targets extracellular pathogens.

• Cellular Immunity: Mediated by T cells; targets infected or abnormal cells.

Interferon, Leukotrienes, Interleukins, Pyrogens, Perforins

• Interferon: Proteins released by virus-infected cells to inhibit viral replication.

• Leukotrienes: Inflammatory mediators derived from arachidonic acid; increase vascular permeability.

• Interleukins: Cytokines that mediate communication between immune cells.

• Pyrogens: Substances that induce fever by acting on the hypothalamus.

• Perforins: Proteins released by cytotoxic T cells and NK cells to form pores in target cell membranes.

Allergic Reactions and Anaphylactic Shock

• Allergic Reaction: Immune response to harmless antigens (allergens), often mediated by IgE and mast cells.

• Anaphylactic Shock: Severe, systemic allergic reaction causing vasodilation, hypotension, and airway constriction; life-threatening.

AIDS

• Acquired Immunodeficiency Syndrome; caused by HIV, which destroys helper T cells, leading to immunosuppression.

Respiratory System

Functions of the Respiratory System

• Gas exchange (O2 in, CO2 out)

• Regulation of blood pH

• Voice production

• Olfaction (smell)

• Protection from pathogens and debris

Upper vs. Lower Respiratory Infections

• Upper Respiratory Tract: Nose, pharynx, larynx; infections include common cold, sinusitis.

• Lower Respiratory Tract: Trachea, bronchi, lungs; infections include bronchitis, pneumonia.

Types of Epithelium Throughout the Respiratory System

• Pseudostratified ciliated columnar epithelium: Lines most of the upper respiratory tract.

• Simple cuboidal epithelium: Found in smaller bronchioles.

• Simple squamous epithelium: Lines alveoli for efficient gas exchange.

Lung Anatomy: Volumes and Capacities

Volume/Capacity	Description
Tidal Volume (TV)	Air inhaled/exhaled in a normal breath
Inspiratory Reserve Volume (IRV)	Extra air inhaled after normal inspiration
Expiratory Reserve Volume (ERV)	Extra air exhaled after normal expiration
Residual Volume (RV)	Air remaining after maximal exhalation
Vital Capacity (VC)	TV + IRV + ERV
Total Lung Capacity (TLC)	VC + RV

Types of Breathing Patterns

• Apnea: Absence of breathing.

• Bradypnea: Slow breathing rate.

• Dyspnea: Difficult or labored breathing.

• Tachypnea: Rapid, shallow breathing.

• Hyperpnea: Increased depth and rate of breathing.

Factors Affecting Lung Compliance

• Elasticity of lung tissue

• Surface tension in alveoli (reduced by surfactant)

• Thoracic cage flexibility

Surfactant

• Lipoprotein produced by type II alveolar cells; reduces surface tension, preventing alveolar collapse.

Gas Laws Relevant to Respiration

• Boyle's Law: Pressure and volume of a gas are inversely related at constant temperature. Equation: $P_1 V_1 = P_2 V_2$

• Henry's Law: The amount of gas dissolved in a liquid is proportional to its partial pressure and solubility. Equation: $C = k P$

• Dalton's Law: Total pressure of a mixture of gases equals the sum of the partial pressures of each gas. Equation: $P_{total} = P_1 + P_2 + \ldots + P_n$

Changes in Intrapulmonary Pressure During Ventilation

• During inspiration, thoracic volume increases, intrapulmonary pressure decreases, and air flows in.

• During expiration, thoracic volume decreases, intrapulmonary pressure increases, and air flows out.

CO2 Transport Equation

• CO2 reacts with water to form carbonic acid, which dissociates into hydrogen and bicarbonate ions. Equation: $\mathrm{CO_2 + H_2O \leftrightarrow H_2CO_3 \leftrightarrow H^+ + HCO_3^-}$

Hemoglobin Saturation

• Refers to the percentage of heme groups in hemoglobin bound to oxygen; affected by PO2, pH, temperature, and CO2 levels.

Hypoventilation vs. Hyperventilation

• Hypoventilation: Decreased ventilation; leads to increased CO2 (hypercapnia) and respiratory acidosis.

• Hyperventilation: Increased ventilation; leads to decreased CO2 (hypocapnia) and respiratory alkalosis.

Obstructive vs. Restrictive Pulmonary Disease

• Obstructive: Increased airway resistance (e.g., asthma, emphysema, chronic bronchitis).

• Restrictive: Decreased lung compliance or expansion (e.g., pulmonary fibrosis, tuberculosis).

Common Respiratory Diseases

• Lung Cancer: Malignant growth in lung tissue; often linked to smoking.

• Emphysema: Destruction of alveolar walls; reduced surface area for gas exchange.

• Tuberculosis: Infectious disease caused by Mycobacterium tuberculosis; forms granulomas in lungs.

Spleen Anatomy

• White Pulp: Lymphatic tissue involved in immune responses.

• Red Pulp: Blood-filled sinuses; removes old erythrocytes.