Untitled Quiz

Blood Physiology

• Blood is part of the extracellular fluid (ECF) circulating within the cardiovascular system.
• Blood volume averages about 80 ml/kg (5-5.5 liters).

General Functions of Blood

• Transport: Carries oxygen (O2) and carbon dioxide (CO2), nutrients, and hormones. Also removes waste products.
• Regulatory Functions: Regulates blood pH, body temperature, and blood pressure (ABP).
• Protective Functions: Involves gamma globulins (forming antibodies for immunity), white blood cells (WBCs) phagocytosing microorganisms, and clotting factors preventing blood loss.

Composition of Blood

• Plasma (55%): Fluid component of blood.
• Blood Cells (45%): Cellular components.
• Red Blood Cells (RBCs):
• Normal Count:
• Child: 3.5-4.5 million/mm³
• Adult Male: 5-5.5 million/mm³
• Adult Female: 4.5-5 million/mm³
• Life Span: Approximately 120 days.
• Contents: Hemoglobin (34% of RBC volume), no nucleus or mitochondria.
• Normal Hemoglobin Content:
• Adult Male: 14-18 g/dL
• Child (5 years): 12 g/dL
• Adult Female: 12-16 g/dL
• Newborn: 18 g/dL
• Anemia: Hemoglobin deficiency (<14 g/dL for men, <12 g/dL for women).
• Polycythemia: Increase in RBC count above normal (6-8 million/mm³).
• Erythropoiesis: Process of RBC production.
• Sites: Red bone marrow (all bones in children, limited in adults).
• Factors Affecting Erythropoiesis:
• Oxygen supply (low O2 stimulates RBC production)
• Nutrients (protein, minerals – iron, copper, cobalt, vitamins – B12, folic acid), Hormones (thyroid hormone, androgens)
• Healthy bone marrow and liver essential.
• White Blood Cells (WBCs):
• Total Count: 4,000-11,000/mm³
• Types: Granular (neutrophils, eosinophils, basophils) and agranular (lymphocytes, monocytes).
• Platelets:
• Shape: Oval or round discs, non-nucleated.
• Count: 150,000-400,000/mm³
• Life Span: 10 days.
• Functions: Important in hemostasis (blood clotting).
• Induces vascular spasm.
• Formation of primary platelet plug.
• Release of platelet phospholipids (e.g., Pf3).
• Stabilization of the blood clot (e.g., fibrin-stabilizing factor).
• Clot retraction (Ca2+).
• Repair damaged blood vessel wall.

Plasma Proteins

• Concentration: 6-8 g/dL.
• Types: Albumin, globulins (including gamma globulins), fibrinogen, clotting factors, and hormones. -Most plasma proteins, apart from gamma globulins, are produced in the liver.
• Functions: Blood viscosity, osmotic pressure, transport of hormones and vitamins, blood clot formation, and immunity.

Blood Immunity

• Innate Immunity (Non-specific): First line of defense.

• Mechanical barriers (skin, GI tract lining)

• Chemical barriers (mucous secretions, stomach acid)

• Non-specific cellular defense mechanisms (phagocytes, natural killer cells).

• Acquired Immunity (Specific): Adaptive immunity.

• Depends on B and T lymphocytes.

• Responds specifically to antigens (bacteria, viruses, tumor cells).

• Types:

• Humoral Immunity: B lymphocytes produce antibodies.

• Cell-Mediated Immunity: T lymphocytes directly attack infected cells.

Hemostasis

• Definition: Stoppage of bleeding from injured blood vessels.
• Steps: Vascular spasm, platelet plug formation, blood clot formation (coagulation).
• Blood clot Formation(Coagulation):
• Prothrombin activator complex formation.
• Prothrombin conversion to thrombin.
• Fibrinogen conversion into fibrin threads.

Bleeding Disorders

• Purpura: Deficiency in blood platelets
• Hemophilia: Congenital deficiency of clotting factors (sex-linked recessive).
• Hemophilia A
• Hemophilia B
• Hemophilia C

Factors Affecting Hemostasis

• Calcium (Ca2+)
• Vitamin K (Crucial for clotting factors)