Chapter XVIII: Cardiovascular System - The Blood

Overview

• Discuss characteristics and components of blood.
• Explore red and white blood cells and platelets.
• Explain hemostasis and blood typing system.

Characteristics of Blood

• Blood is a connective tissue with 4-6 liters in volume.
• Functions:
  • Transportation: Gases, nutrients, hormones, waste products.
  • Regulation: Body temperature, osmotic pressure, pH levels (7.35-7.45).
  • Protection: Clotting (hemostasis), immune protection via white blood cells and proteins.

Components of Blood

• Cells and Plasma:
  • Blood Plasma: Liquid portion containing water, proteins (albumin, fibrinogen, immunoglobulins).
  • Blood Cells: Red blood cells, white blood cells, platelets.

Blood Cells

• Red Blood Cells (Erythrocytes):

  • Transport oxygen via hemoglobin.
  • Biconcave, no nucleus, live ~120 days.
  • Produced in red bone marrow.
  • Essential vitamins/minerals for RBC production: Iron, coagulation requires calcium.

• White Blood Cells (Leukocytes):

  • Fight infection, divided into granular (neutrophils, eosinophils, basophils) and agranular (lymphocytes, monocytes).
  • Types:
    • Neutrophils: Most common, phagocytic.
    • Lymphocytes: B-cells, T-cells, NK cells, involved in immunity.
    • Monocytes: Develop into macrophages, phagocytic.
    • Eosinophils: Respond to allergens and parasites.
    • Basophils: Release histamine, involved in inflammation.
  • Produced in red bone marrow, can live for a few days except lymphocytes.

• Platelets (Thrombocytes):

  • Fragments from megakaryocytes.
  • Involved in clotting.

Hemostasis

• Processes: Vascular spasm, platelet plug formation, coagulation.
• Clotting Pathways:
  • Intrinsic Pathway: Triggered by platelet activation.
  • Extrinsic Pathway: Triggered by tissue factor from damaged tissues.
  • Both lead to common pathway producing thrombin which converts fibrinogen to fibrin.
• Vitamin K: Essential for clotting factor production.

Blood Typing and Rh Factor

• Blood Types: A, B, AB, O determined by surface antigens.
• Agglutination: Clumping due to antigen-antibody interaction.
• Rh Factor:
  • Rh positive/negative based on D antigen presence.
  • Rh incompatibility in pregnancy can lead to hemolytic disease of the newborn.

Conclusion

• Understanding the properties and functions of blood and its components is crucial for maintaining health and managing disorders related to blood and its functions.