Hematology Overview and Blood Functions

Hematology

• The study of blood, bone marrow, and the hemostasis system.
• Includes disorders of lymph nodes and related tissues.
• Encompasses a range of diseases including:
  • Genetic diseases (e.g., hemoglobinopathies, thalassemias)
  • Immune diseases (e.g., immune hemolytic anemia)
  • Malignancies (e.g., leukemias, lymphomas).
• Has played a crucial role:
  • Studying blood and its disorders
  • Understanding gene structure and function
  • Recognizing the importance of chromosomal abnormalities in malignancies
  • Advancing molecular biology of neoplasia

Blood

• Constitutes 6-8% of body weight in healthy adults.
• Total volume is approximately 5 liters.
• Distribution:
  • Systemic veins: 3 liters
  • Arterial system: 1 liter
  • Lungs: 1 liter
• Specific gravity: 1.050 - 1.060
• Viscosity: 2-5 times that of water
• Salinity: 0.85

Blood Functions

• Respiration:
  • Transport of oxygen from lungs to tissues.
  • Transport of CO2 from tissues to lungs for excretion.
• Nutrition:
  • Transports absorbed food materials from the digestive system to other parts of the body.
• Excretion:
  • Transports metabolic wastes to kidneys, lungs, skin, and intestines for removal.
• Acid-Base Balance:
  • Maintains normal blood pH (7.35-7.45).
• Water Balance:
  • Regulates water exchange between circulating fluid and tissue fluid.
• Temperature Regulation:
  • Distributes body heat; blood temperature is 38°C.
• Defense:
  • Provides defense against infection through white blood cells (WBCs) and circulating antibodies.
• Hormone Transport:
  • Transports hormones for metabolic regulation.

Blood Composition

• Consists of two phases:
  • Liquid phase (plasma):
    • Water, electrolytes (Na+, Ca++, HCO3-, Cl-), proteins, and other substances like sugar, fat, vitamins, and hormones.
  • Solid phase (formed elements):
    • Erythrocytes (red blood cells)
    • Leukocytes (white blood cells)
    • Platelets

Blood Components

• Plasma: 55% of blood volume

  • Serum: Plasma without fibrinogen, fibrin, Factor II, Factor V, Factor VIII. Rich in serotonin.
  • Fibrinogen: Key component of blood clotting.

• Solid Phase: 45% of blood volume

  • Red blood cells, white blood cells, and platelets.

Plasma

• Normal volume: 25-45 ml/kg of body weight.
• Specific gravity: 1.027.
• Components:
  • Approximately 92% water
  • 8% substances including proteins, ions, nutrients, gases, and waste products.
• Plasma proteins:
  • Albumin: 60% of plasma proteins; important for osmotic pressure of blood and water movement.
  • Globulin: 36% of plasma proteins; includes antibodies and complement (important in immune system).
  • Fibrinogen: 4% of plasma proteins; crucial for blood clot formation.

Plasma Volume

• Remains relatively constant.
• Water intake: Digestive tract
• Water loss: Kidneys, lungs, digestive tract, skin.

Composition of Plasma

• Electrolytes: Cations (Na+, K+, Mg++) and anions (Cl-, HCO3-, SO4, PO4).

• Proteins: Albumin, globulin, fibrinogen, transferrin, haptoglobin, hemopoietin.

• Other contents: Cholesterol, triglycerides, lipoproteins, glucose, urea, uric acid, iron, coagulation factors.

• Note: All plasma proteins are produced by the liver except for gamma-globulin, which is produced by plasma cells.

Functions of Plasma Proteins

• Osmotic pressure (oncotic pressure): Maintained at 25 mmHg, primarily by albumin. Hypoalbuminemia can lead to reduced oncotic pressure and edema.
• Transport system: Many substances are transported in the blood by plasma proteins:
  • Albumin: Ca+2, bilirubin, sulpha drugs.
  • Alpha-globulin: B12, thyroxin (T3), cortisol.
  • Beta-globulin: Cholesterol, lipids, insulin, vitamin A, PO4, K+.

This quiz covers key concepts in hematology, including the study of blood, bone marrow, and related disorders. It also delves into the functions of blood in respiration and its significance in various diseases. Test your knowledge of hematological concepts and the composition of blood.