Untitled Quiz

Blood Physiology & Pathophysiology

• Blood is a circulating tissue composed of plasma and cells.
• Plasma constitutes 55% of blood volume, while cells account for the remaining 45%.
• Plasma is primarily water (90%) with soluble proteins (7-8%).

Function of Blood

• Transports oxygen and nutrients, removing waste products.
• Transports hormones between tissues and organs.
• Maintains homeostasis by transferring heat to the skin and acting as a buffer system for pH.

Temperature Regulation

• Nervous system signals dermal blood vessels to dilate or constrict to regulate body temperature.
• Sweat glands secrete sweat to cool the body when temperature rises above normal (37°C or 98.6°F).
• Hypothalamus regulates body temperature.

pH Regulation

• Blood acts as a buffer system, maintaining pH equilibrium.
• Bicarbonate (HCO3-) in the blood neutralizes excess acid (H+).
• Kidneys remove excess acid through urine.

Composition of Blood

• Plasma:
  • 55% of blood volume
  • Contains proteins, water, nutrients, waste products, and gases.
• Cells:
  • 45% of blood volume
  • Consist of red blood cells, white blood cells, and platelets.

Plasma Proteins

• Albumin: Produced in the liver, maintains osmotic balance between blood and tissue fluids, and transports vitamins, drugs, and bilirubin.
• Globulins: Gamma globulins assist the immune system in fighting infections.
• Clotting proteins: Primarily produced in the liver; fibrinogen is crucial in blood clot formation.

Red Blood Cells (Erythrocytes)

• Formed in bone marrow (erythropoiesis).
• Bi-concave shape for efficient oxygen transport through capillaries.
• Lack nuclei, with a lifespan of about 120 days.
• Hemoglobin is the main component, transporting oxygen to tissues and carbon dioxide (carbaminohemoglobin).

Destruction of Red Blood Cells

• Breakdown occurs in the spleen.
• Globin is broken down into amino acids for recycling.
• Iron is recovered and reused.
• Heme is broken down to bilirubin, contributing to the brown color of feces (stercobilin).
• Bilirubin is processed and excreted.

White Blood Cells (Leukocytes)

• Primarily produced in bone marrow.
• Granular leukocytes: Neutrophils, eosinophils, and basophils. Important in fighting infections and allergic reactions.
• Agranular leukocytes: Monocytes and lymphocytes (B and T cells).
• Monocytes: Become macrophages and engulf pathogens.
• Lymphocytes: B cells produce antibodies for pathogen targeting; T cells target non-normal body cells.

Platelets (Thrombocytes)

• Have no nucleus.
• Derived from megakaryocytes in bone marrow.
• Thrombopoietin regulates their production.
• 8-10 days lifespan, promoting blood clotting at injury sites.
• Secrete factors like Thromboxane A2 and Serotonin, which induce platelet aggregation and vasoconstriction to stop bleeding.

Blood Types (ABO system)

• Classified by antigens (A, B, AB, or O) present on red blood cells (RBCs).
• Blood plasma contains antibodies (anti-A, anti-B) to counteract incompatible antigens.
• Individuals with type O blood are universal donors; type AB are universal recipients.

Blood Types (Rh system)

• Involves RhD antigen on RBCs—positive if present, negative if absent.
• Incompatible Rh blood transfusions can cause severe reactions (hemolysis) in the recipient.

Hemostasis

• Natural process stopping blood flow from injury.
• Three stages:
  • Vasoconstriction: Narrowing of blood vessels to slow blood flow.
  • Platelet plug formation: Platelets aggregate at injury site and adhere to form a temporary plug.
    • Platelets release ADP and Thromboxane A2, to promote further aggregation and vasoconstriction.
  • Blood clot formation: Fibrin threads form a network around the platelet plug, enhancing blood clot formation.
    • Prothrombin converts into thrombin, which cleaves fibrinogen into fibrin threads.

Blood Disorders

• Hemophilia: Inherited deficiency of clotting factors (VIII or IX).
• Anemia: Reduced red blood cell count or hemoglobin deficiency.
• Causes of anemia: excessive blood loss, excessive red blood destruction, deficient RBC production, or dietary iron deficiency.
• Further Classifications of Anemia:*
• Iron deficiency anemia
• Megaloblastic anemia
• Hemolytic anemia
• Aplastic anemia
• Hemorrhagic anemia

Hemolytic Disease of the Newborn

• Condition where Rh-negative mother carries an Rh-positive fetus.
• Mother’s antibodies attack the fetus’s red blood cells.
• Treatment includes Rh immune globulin (RhoGAM) injections to prevent sensitization and additional treatments upon delivery.

Blood Transfusion

• ABO and Rh blood factor compatibility is essential to prevent reactions.
• Cross-matching of donor and recipient blood determines compatibility.