Blood Physiology Lecture 01

Learning Outcomes

• Understand physiology of red and white blood cells.
• Identify blood groups and compatibility for transfusions.
• Describe body fluid composition.
• Explain blood transfusion procedures and blood grouping.

Composition of Blood

• Blood consists of 45% cellular components (RBCs, WBCs, platelets) and 55% plasma.
• Plasma is 90% water, 8% proteins, and contains inorganic salts, lipids, sugars, amino acids, antibodies, hormones, electrolytes, waste, and ions.
• Blood's ionic composition mirrors that of interstitial fluid.

Haematopoiesis and Erythropoiesis

• Haematopoiesis: formation and maturation of blood cells, occurring in red bone marrow.
• Driven by haemocytoblasts, which are undifferentiated stem cells.
• Erythropoiesis specifically refers to RBC formation; thrombopoiesis refers to platelet production.

Major Functions of Blood

• Distribution: transports oxygen, carbon dioxide, nutrients, waste, and hormones.
• Regulation: maintains pH, fluid balance, and body temperature.
• Protection: seals vascular damage and provides defense against pathogens through leukocytes and antibodies.

Red Blood Cells (RBCs)

• Most abundant cells (4-6 million per microliter) with a lifespan of 120 days; formed in bone marrow.
• Mature RBCs lack nuclei and are biconcave, measuring 6-8 micrometers in diameter.
• Contain haemoglobin, responsible for oxygen and carbon dioxide transport.
• Conditions: Polycythemia (high RBC levels) and erythropenia (low RBC levels).

White Blood Cells (WBCs)

• Largest blood cells but present in lower numbers (4,500-11,000 per microliter).
• Formed in bone marrow and lymph glands; crucial for immune function.
• Size ranges from 8-20 micrometers with a varying life span (from hours to years).
• Five types: Neutrophils, Eosinophils, Basophils, Lymphocytes, Monocytes.
• Conditions: Leukocytosis (high WBC levels) and leucopenia (low WBC levels).

Platelets (Thrombocytes)

• Smallest blood cells (1-4 micrometers); formed as fragments of megakaryocytes in bone marrow.
• Life span of 8-12 days; normal count is 150,000-400,000 per microliter.
• Involved in clotting, sealing wounds, and repairing vessels.
• Conditions: Thrombocytosis (high platelet levels) and thrombocytopenia (low platelet levels).

Blood Transfusion

• A procedure to deliver healthy blood via IV; necessary for blood loss, anemia, and certain blood disorders.
• Types include whole blood, red blood cells, platelets, and plasma.
• Risks involve mismatched transfusions leading to hemolytic shock and renal failure, and matched transfusions causing circulatory overload or disease transmission.

Blood Grouping

• ABO system identified by Karl Landsteiner based on antigens A and B present on RBCs.
• Rh system indicates the presence (Rh+) or absence (Rh-) of a specific antigen, essential for compatibility in transfusions.

Erythroblastosis Faetalis

• A condition where fetal erythrocytes are destroyed due to maternal immune response against incompatible blood groups.
• Major causes include Rh incompatibility and ABO incompatibility.
• In severe cases, intrauterine blood transfusions may be required to treat fetal anemia.

This quiz covers the physiological aspects of blood, including the functions of red and white blood cells. It also delves into blood groups, compatibility for transfusions, and the composition of body fluids. Perfect for anyone studying human biology or related fields.