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Blood and Hematology - Anatomy & Physiology

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Terms in this set (20)

  • What are the three main functions of blood?
    Transportation of gases, nutrients, wastes; regulation of pH, temperature, and water content; protection through immune defense and clotting.
  • What is the typical composition of blood by volume?
    About 44% red blood cells (RBCs), 1% white blood cells (WBCs) and platelets (buffy coat), and 55% plasma.
  • Describe the structure and function of red blood cells (erythrocytes).
    Anucleate, biconcave discs that increase surface area for gas exchange; contain hemoglobin to bind oxygen; functional for ~120 days.
  • What is hemoglobin composed of and what is its role?
    Hemoglobin has 4 polypeptide chains (globins), each with a heme group that binds one oxygen molecule; it transports oxygen in RBCs.
  • Where does hematopoiesis occur and what does it produce?
    Occurs in red bone marrow; produces all blood formed elements including RBCs, WBCs, and platelets.
  • What hormone regulates erythropoiesis and what triggers its release?
    Erythropoietin, released by kidneys in response to low blood oxygen (hypoxia), stimulates RBC production.
  • What are common causes and types of anemia?
    Iron-deficiency anemia (low iron for Hb), pernicious anemia (vitamin B12 deficiency), and sickle cell anemia (abnormal Hb causing sickled RBCs).
  • What are the main types of white blood cells (WBCs)?
    Granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (monocytes, lymphocytes).
  • What is the function of neutrophils?
    Phagocytic cells that combat bacterial infections and inflammation.
  • What role do eosinophils play in the immune system?
    Combat parasitic worm infections and modulate allergic responses.
  • What is the function of basophils?
    Release histamine and other chemicals during inflammatory and allergic reactions.
  • What are the two main types of lymphocytes and their functions?
    B lymphocytes produce antibodies; T lymphocytes mediate cell-mediated immunity and directly destroy pathogens.
  • What are platelets and their role in hemostasis?
    Anucleate cell fragments from megakaryocytes; they promote blood clotting by forming platelet plugs and releasing clotting factors.
  • Describe the three main steps of hemostasis.
    (1) Vascular spasm - vasoconstriction; (2) Platelet plug formation - platelets adhere and aggregate; (3) Coagulation - fibrin clot formation.
  • What triggers the intrinsic and extrinsic pathways of the clotting cascade?
    Intrinsic: activators within blood or damaged vessel; Extrinsic: tissue factor from damaged cells outside vessel.
  • What is the role of thrombin in clot formation?
    Converts fibrinogen into fibrin strands that form the structural basis of a blood clot.
  • What is the significance of blood antigens and antibodies in blood typing?
    Blood type is determined by antigens on RBCs and antibodies in plasma; incompatible antigen-antibody binding causes agglutination and hemolysis.
  • What blood type is the universal donor and why?
    Type O blood; it has no antigens on RBCs, so it does not trigger immune reactions in recipients.
  • What is the Rh factor and its clinical importance?
    Rh+ means RBCs have Rh antigen; Rh- means they do not. Rh incompatibility can cause hemolytic disease of the newborn.
  • How are worn-out RBCs recycled in the body?
    Macrophages in the spleen digest RBCs; heme is broken down into iron (recycled) and bilirubin (excreted).