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Anatomy & Physiology II: Blood - Key Concepts

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이 집합의 용어 (29)

  • Primary functions of blood
    Transport of O2, nutrients, wastes, and hormones; Regulation of body temperature, pH, and fluid volume; Protection against blood loss and infection.
  • Composition of blood
    Blood is a connective tissue with a fluid matrix called plasma and living cells called formed elements (erythrocytes, leukocytes, platelets).
  • Hematocrit
    The percentage of blood volume composed of erythrocytes, normally about 45%.
  • Physical characteristics of blood
    Sticky, opaque fluid with metallic taste; color varies with oxygen content; pH 7.35–7.45; volume ~5 L in adults.
  • Major plasma proteins and their functions
    Albumin (carrier, buffer, osmotic pressure), globulins (immune function), and fibrinogen (clotting).
  • Erythrocyte structure
    Biconcave, anucleate cells filled with hemoglobin; flexible due to spectrin; optimized for gas transport.
  • Hemoglobin composition
    Four polypeptide chains (2 alpha, 2 beta) each with an iron-containing heme group that binds oxygen.
  • Erythropoiesis
    Process of RBC formation in red bone marrow, taking about 15 days from stem cell to mature erythrocyte.
  • Regulation of erythropoiesis
    Controlled by erythropoietin (EPO) released by kidneys in response to hypoxia; testosterone enhances EPO production.
  • Dietary requirements for RBC production
    Adequate amino acids, iron (stored as ferritin), vitamin B12, and folic acid are essential for erythropoiesis.
  • Life span and fate of erythrocytes
    Live 100–120 days; old RBCs are phagocytized in spleen; hemoglobin components recycled or excreted.
  • Anemia
    Condition with low oxygen-carrying capacity due to blood loss, decreased RBC production, or increased RBC destruction.
  • Sickle-cell anemia
    Genetic disorder with abnormal hemoglobin S causing RBCs to sickle, block vessels, and reduce oxygen delivery.
  • Leukocytes (WBCs) general features
    Complete cells with nuclei; defend against disease; can leave bloodstream by diapedesis.
  • Granulocytes vs Agranulocytes
    Granulocytes have visible cytoplasmic granules (neutrophils, eosinophils, basophils); agranulocytes lack granules (lymphocytes, monocytes).
  • Neutrophils
    Most abundant WBCs; multilobed nucleus; phagocytic; kill bacteria via respiratory burst.
  • Eosinophils
    Combat parasitic worms; involved in allergy and asthma; bilobed nucleus with red granules.
  • Basophils
    Rarest WBCs; contain histamine granules; promote inflammation and vasodilation.
  • Lymphocytes
    Crucial for immunity; T cells attack infected cells; B cells produce antibodies.
  • Monocytes
    Largest WBCs; differentiate into macrophages; phagocytic and activate lymphocytes.
  • Platelets
    Cell fragments from megakaryocytes; involved in clot formation; circulate 4–5 days.
  • Three steps of hemostasis
    1) Vascular spasm, 2) Platelet plug formation, 3) Coagulation to form fibrin clot.
  • Coagulation pathways
    Intrinsic pathway triggered by blood contact with collagen; extrinsic pathway triggered by tissue factor; both activate factor X.
  • Role of thrombin in coagulation
    Converts fibrinogen to fibrin and activates factor XIII to stabilize clot.
  • Anticoagulants in blood
    Prevent unwanted clotting; include antithrombin III, heparin, nitric oxide, and prostacyclin.
  • Blood groups ABO system
    Based on presence of A and/or B antigens on RBCs; antibodies in plasma react against absent antigens.
  • Rh blood group system
    Presence (Rh+) or absence (Rh–) of D antigen; Rh– individuals form antibodies only after exposure.
  • Hemolytic disease of the newborn
    Rh– mother sensitized to Rh+ fetus blood produces antibodies that attack fetal RBCs in subsequent pregnancies.
  • Blood transfusion compatibility
    Matching donor and recipient ABO and Rh types prevents agglutination and hemolysis.