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Anatomy & Physiology: Blood, Lymphatic, and Respiratory Systems

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  • Core functions of blood

    Transportation of gases, nutrients, wastes, and hormones; Regulation of temperature, pH, and fluid volume; Protection via clotting and immune defense.
  • Composition of whole blood

    Plasma (~55%), buffy coat (<1%) with leukocytes and platelets, and erythrocytes (~45%, hematocrit).
  • Major plasma proteins and functions

    Albumin: carrier, buffer, osmotic pressure; Globulins: transport and antibodies; Fibrinogen: clotting precursor.
  • Erythrocyte structural adaptations

    Biconcave shape for surface area, anucleate with no mitochondria to avoid oxygen use, contains hemoglobin for oxygen transport.
  • Hemoglobin structure and function

    Four polypeptide chains each with an iron-containing heme group; binds up to four oxygen molecules reversibly.
  • Erythropoiesis regulation

    Produced in red bone marrow; stimulated by erythropoietin from kidneys in response to low oxygen (hypoxia).
  • Leukocyte classification

    Granulocytes: neutrophils, eosinophils, basophils; Agranulocytes: lymphocytes and monocytes.
  • Functions of neutrophils

    Most abundant WBC; phagocytize bacteria using respiratory bursts and enzymes.
  • Role of eosinophils

    Attack parasitic worms and modulate allergic reactions and asthma.
  • Basophil function

    Release histamine (vasodilator) and heparin (anticoagulant) during inflammation.
  • Lymphocyte types and roles

    T cells: cell-mediated immunity; B cells: produce antibodies for humoral immunity.
  • Platelets origin and function

    Cell fragments from megakaryocytes; contain clotting factors; lifespan 8–10 days; essential for hemostasis.
  • Three steps of hemostasis

    1. Vascular spasm; 2. Platelet plug formation; 3. Coagulation forming fibrin mesh.
  • Clot retraction and fibrinolysis

    Platelets contract to close vessel edges; plasmin enzymatically dissolves clots after repair.
  • ABO blood group antigens and antibodies

    Type A: A antigen, anti-B antibody; B: B antigen, anti-A antibody; AB: both antigens, no antibodies; O: no antigens, anti-A and anti-B antibodies.
  • Rh blood group significance

    Rh+ carry Rh antigen; Rh- develop anti-Rh antibodies if exposed; important in pregnancy for hemolytic disease.
  • Lymphatic system core functions

    Fluid recovery, absorption of dietary lipids, and immune defense.
  • Primary lymphoid organs

    Red bone marrow (B cell maturation) and thymus (T cell maturation).
  • Secondary lymphoid organs

    Lymph nodes, spleen, and MALT (tonsils, Peyer’s patches, appendix).
  • Innate immune defenses

    Surface barriers (skin, mucous membranes), phagocytes, natural killer cells, inflammation, fever, antimicrobial proteins.
  • Adaptive immunity characteristics

    Specificity, systemic action, and memory; includes cell-mediated (T cells) and humoral (B cells/antibodies) immunity.
  • T cell types and functions

    Helper T cells (CD4): activate immune cells; Cytotoxic T cells (CD8): kill infected/tumor cells; Regulatory T cells: suppress immune response.
  • B cell activation and clonal selection

    Antigen binds receptor, B cell proliferates, differentiates into plasma cells (antibody producers) and memory B cells.
  • Five major antibody classes (GAMED)

    IgG: most abundant; IgA: mucosal secretions; IgM: first responder; IgE: allergic responses; IgD: B cell receptor.
  • Primary function of the respiratory system

    Pulmonary ventilation and gas exchange; also olfaction, speech, and acid-base balance.
  • Conducting vs respiratory zones

    Conducting zone: air passage without gas exchange; Respiratory zone: site of gas exchange (alveoli and respiratory bronchioles).
  • Mechanics of pulmonary ventilation

    Inspiration: diaphragm and external intercostals contract, increasing thoracic volume and lowering pressure; expiration: muscles relax, volume decreases, pressure rises.
  • Gas transport in blood

    Oxygen mostly bound to hemoglobin (~98.5%); CO2 transported dissolved, bound to hemoglobin, or as bicarbonate ions.
  • Neural control of respiration

    Medullary respiratory centers (VRG and DRG) generate rhythm and integrate input; pontine centers smooth breathing transitions.