State the functions of the components of blood: (a) red blood cells – oxygen transport (b) white blood cells – antibody production by lymphocytes and engulfing pathogens by phagocytes (c) platelets – clotting by converting soluble fibrinogen to insoluble fibrin to prevent blood loss and the entry of pathogens (d) plasma – transport, limited to: blood cells, ions, glucose, amino acids, hormones, carbon dioxide, urea, vitamins and plasma proteins

The components of blood play essential roles in maintaining bodily functions and protecting the body from disease. Here’s a detailed description of the functions of red blood cells, white blood cells, platelets, and plasma:

(a) Red Blood Cells (Erythrocytes)

• Function: The primary function of red blood cells is oxygen transport. They carry oxygen from the lungs to the tissues and return carbon dioxide from the tissues back to the lungs for exhalation.
• Mechanism: Red blood cells contain hemoglobin, a protein that binds oxygen molecules. Each hemoglobin molecule can carry four oxygen molecules, allowing red blood cells to efficiently transport oxygen throughout the body.

(b) White Blood Cells (Leukocytes)

• Function: White blood cells are crucial for the immune response, with two main functions:
  • Antibody Production: Lymphocytes, a type of white blood cell, produce antibodies that specifically target pathogens (such as bacteria and viruses). These antibodies bind to antigens on the surface of pathogens, marking them for destruction by other immune cells.
  • Engulfing Pathogens: Phagocytes, another type of white blood cell (including neutrophils and monocytes), engulf and digest pathogens through a process called phagocytosis. They act as the first line of defense against infections by identifying and destroying harmful microorganisms.

(c) Platelets (Thrombocytes)

• Function: Platelets are essential for clotting, which prevents blood loss and protects against pathogen entry when injuries occur.
• Mechanism: When a blood vessel is damaged, platelets adhere to the site of injury and aggregate to form a temporary plug. They release chemicals that convert soluble fibrinogen into insoluble fibrin, creating a stable clot that seals the wound and prevents further bleeding.

(d) Plasma

• Function: Plasma serves as the liquid medium for transporting various substances throughout the body.
• Composition and Transport:
  • Blood Cells: Carries red blood cells, white blood cells, and platelets.
  • Ions: Transports essential electrolytes such as sodium, potassium, calcium, and bicarbonate, which are vital for various physiological functions.
  • Glucose: Provides energy to cells through the transport of glucose from digestion.
  • Amino Acids: Transports building blocks for protein synthesis.
  • Hormones: Carries hormones from endocrine glands to target organs to regulate bodily functions.
  • Carbon Dioxide: Transports carbon dioxide from tissues back to the lungs for exhalation.
  • Urea: Carries waste products like urea from metabolism to the kidneys for excretion.
  • Vitamins: Transports vitamins necessary for various biochemical processes in the body.
  • Plasma Proteins: Includes albumin (for maintaining osmotic pressure), globulins (for immune function), and fibrinogen (for clotting).