Lymphatic, Immune, and Respiratory Systems: Study Guide

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Chapter 20: Lymphatic System & Immunity

General Functions of the Lymphatic System

The lymphatic system is essential for maintaining fluid balance, defending the body against pathogens, and facilitating the absorption of dietary fats.

Fluid Balance: Returns excess interstitial fluid to the bloodstream.
Immune Defense: Houses and transports lymphocytes and other immune cells.
Absorption of Fats: Absorbs lipids from the digestive tract via lacteals.

Lymph and Lymphatic Vessels

Lymphatic vessels transport lymph, a fluid derived from interstitial fluid, throughout the body.

Comparison: Lymphatic vessels are similar to veins but have thinner walls and more valves.
Structure: Include lymphatic capillaries, vessels, trunks, and ducts.
Lymph Circulation: Lymph flows from tissues to lymphatic capillaries, through vessels and nodes, and finally into the venous system.
Mechanisms: Movement is aided by skeletal muscle contraction, respiratory movements, and valves.
Whole blood: circulates in blood vessels and contains plasma, RBC, WBC, and platelets.
Interstitial fluid: is the fluid surrounding cells, lacking cells, and most proteins but containing water, ions, and nutrients.
Lymph: is formed from interstitial fluid transported through lymphatic vessels, and contains a higher concentration of proteins, WBC (lymphocytes) to aid in immune function and remove excess fluid.
Blood vessels preform a closed loop system for a high pressure circulation of blood, which carries oxygen and nutrients featuring thick walls and a heart as the pump. in contrast lymphatic vessels form an open ended system for low pressure collection, and return of tissue fluid (lymph) with thinner walls and more permeable capillaries with anchoring filaments and a reliance on muscle contraction and valves to return the lymph to the blood.
Lymphatic circulation pathway; Origination ( Interstitial fluid (excess fluid from blood capillaries) accumulates in tissues lymphatic capillaries, the smallest lymphatic vessels, collect this fluid and form lymph) --> movement through lymph nodes (WBC (lymphocytes) in the lymph nodes remove bacteria, viruses, and other debris) --> Larger lymphatic vessels (Lymph exits the lymph nodes and enters larger lymphatic vessels called collecting ducts, These ducts carry lymph towards the thoracic duct (left side of the body) or the right lymphatic duct (right side of the body) --> Empties into vein ( The thoracic duct and right lymphatic duct empty into the subclavian vein on their respective sides).
Lymph formation; begins when blood plasma filters from capillaries into tissues, creating interstitial fluid, which is then collected by lymphatic capillaries to become lymph. Lymph circulation relies on intrinsic factors, such as smooth muscle contraction in the vessel walls and one-way valves that prevent backflow, and extrinsic factors, including muscle contractions, respiratory movements, and arterial pulses that propel lymph through progressively larger vessels and lymph nodes.

Lymphatic Cells, Tissues, and Organs

Lymphatic tissues and organs are specialized for immune surveillance and response.

Lymphatic Tissue: Composed of lymphocytes and supporting cells in a reticular connective tissue matrix.
Lymphatic Nodules: Small, localized clusters of lymphatic tissue (B&T cells) (e.g., MALT) found in mucosal membranes, such as digestive, respiratory, and urogenital tracts.
Lymphatic Organs: Include lymph nodes, thymus, and spleen, each with distinct structure and function.
lymph nodes- trap pathogens and house immune cells; bean shaped filters found in groups throughout the body (neck, armpits, and groin).
thymus- serves as trading ground for T cells, two lobed organ in the chest that is bigger in children and shrinks with age.
Spleen- filers blood, removes old RBC, and plays a role in immune response. located in upper left abdominal.

Introduction to Innate (Nonspecific) and Adaptive (Specific) Immune Responses

The immune system is divided into innate (nonspecific) and adaptive (specific) defenses.

Innate Immunity: Provides immediate, general protection (e.g., barriers, phagocytes).
Adaptive Immunity: Provides specific, long-term defense (e.g., T and B lymphocytes).
Leukocytes: Various types play roles in both innate and adaptive responses.

Innate (Nonspecific) Defenses

Innate defenses include physical barriers, chemical barriers, and cellular responses.

Surface Barriers: Skin and mucous membranes.
Cellular Defenses: Phagocytes, natural killer cells.
Chemical Defenses: Lysozyme, complement proteins, interferons.
Inflammation and Fever: Key responses to infection or injury.

Overview of Adaptive (Specific) Immunity

Adaptive immunity involves highly specific responses to particular antigens.

Humoral Immunity: Mediated by B cells and antibodies.
Cell-Mediated Immunity: Mediated by T cells.
Immunological Memory: Enables faster, stronger responses upon re-exposure.

Antigens and Antigen Processing

Antigens are substances that elicit immune responses; antigen processing is essential for adaptive immunity.

Antigen: Any substance recognized as foreign by the immune system.
Self-Antigen: Body's own molecules, usually not attacked by the immune system.
Major Histocompatibility Complex (MHC): Proteins that present antigens to T cells.
Antigen-Presenting Cells (APCs): Cells that process and present antigens (e.g., dendritic cells, macrophages).

Lymphocytes and Their Role in Adaptive (Specific, Acquired) Immunity

Lymphocytes are central to adaptive immunity, with distinct roles for B and T cells.

B Cells: Produce antibodies (humoral immunity).
T Cells: Include helper T cells (CD4+), cytotoxic T cells (CD8+), and regulatory T cells.
Comparison: B cells target extracellular pathogens; T cells target infected or abnormal cells.

Antibodies and Their Role in Adaptive (Specific) Immunity

Antibodies are proteins produced by B cells that bind to specific antigens.

Structure: Y-shaped molecules with variable and constant regions.
Classes: IgG, IgA, IgM, IgE, IgD (each with specific functions).
Mechanisms: Neutralization, agglutination, precipitation, complement activation.

Applied Immunology

Immunity can be acquired naturally or artificially, and can be active or passive.

Active Immunity: Results from exposure to antigen (infection or vaccination).
Passive Immunity: Results from transfer of antibodies (e.g., maternal antibodies, immunoglobulin therapy).

Predictions Related to Disruption of Homeostasis

Disorders of the lymphatic and immune systems can lead to significant health issues.

Lymphedema: Swelling due to lymphatic obstruction.
Allergic Reactions: Hypersensitivity of the immune system.
Immunodeficiency Disorders: SCID, HIV/AIDS.

Chapter 21: Respiratory System

General Functions of the Respiratory System

The respiratory system is responsible for gas exchange, pH regulation, and vocalization.

Ventilation: Movement of air into and out of the lungs.
Gas Exchange: Exchange of oxygen and carbon dioxide between air and blood, and between blood and tissues.
Other Functions: Olfaction, sound production, and protection from inhaled pathogens.

Gross and Microscopic Anatomy of the Respiratory Tract and Related Organs

The respiratory tract includes conducting and respiratory portions, each with distinct structures and functions.

Conducting Portion: Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles.
Respiratory Portion: Respiratory bronchioles, alveolar ducts, alveoli.
Larynx: Contains vocal cords; involved in sound production.
Trachea: Supported by C-shaped cartilage rings; conducts air to bronchi.
Lungs: Divided into lobes; contain bronchi, bronchioles, and alveoli for gas exchange.

Mechanics of Ventilation

Ventilation is driven by pressure changes in the thoracic cavity.

Muscles: Diaphragm and intercostal muscles are primary muscles of inspiration.
Pressures: Atmospheric, intrapulmonary, and intrapleural pressures determine airflow.
Boyle's Law: (Pressure and volume are inversely related).
Compliance: The ease with which lungs expand; affected by elasticity and surface tension.
Airway Resistance: Influenced by airway diameter and smooth muscle tone.

Pulmonary Volumes and Capacities

Pulmonary volumes and capacities are measurements used to assess lung function.

Tidal Volume (TV): Volume of air inhaled or exhaled in a normal breath.
Inspiratory Reserve Volume (IRV): Additional air inhaled after a normal inspiration.
Expiratory Reserve Volume (ERV): Additional air exhaled after a normal expiration.
Residual Volume (RV): Air remaining in lungs after maximal exhalation.
Vital Capacity (VC):
Total Lung Capacity (TLC):

Mechanisms of Gas Exchange in the Lungs and Tissues

Gas exchange occurs by diffusion, driven by partial pressure gradients.

Partial Pressure: The pressure exerted by a single gas in a mixture.
Oxygen Transport: Mostly bound to hemoglobin; some dissolved in plasma.
Carbon Dioxide Transport: Dissolved in plasma, bound to hemoglobin, or as bicarbonate ions.
Bohr Effect: (Increased CO2 or H+ decreases hemoglobin's affinity for O2).
Haldane Effect: Deoxygenated blood can carry more CO2.
Bicarbonate Buffer System:

Control of Pulmonary Ventilation

Ventilation is regulated by neural and chemical mechanisms.

Respiratory Centers: Located in the medulla oblongata and pons.
Chemoreceptors: Detect changes in CO2, O2, and pH.
Hyperventilation: Increased rate and depth of breathing.
Hypoventilation: Decreased rate and depth of breathing.
Apnea: Temporary cessation of breathing.

Predictions Related to Homeostatic Imbalance

Disorders of the respiratory system can disrupt gas exchange and homeostasis.

Acute Disorders: IRDS, asthma, pneumonia.
Chronic Disorders: COPD (chronic bronchitis, emphysema), lung cancer.