State the functions of the following components of blood: (a) red blood cells in transporting oxygen, including the role of haemoglobin (b) white blood cells in phagocytosis and antibody production (c) platelets in clotting (details are not required) (d) plasma in the transport of blood cells, ions, nutrients, urea, hormones and carbon dioxide

Here are the functions of the specified components of blood:

(a) Red Blood Cells (RBCs) in Transporting Oxygen

• Function: Red blood cells are primarily responsible for transporting oxygen from the lungs to the body’s tissues and returning carbon dioxide from the tissues back to the lungs.
• Role of Hemoglobin: Hemoglobin, a protein found in red blood cells, plays a critical role in this process. Each hemoglobin molecule can bind up to four oxygen molecules due to its iron-containing heme groups. This binding allows red blood cells to carry oxygen efficiently; approximately 95% of hemoglobin is saturated with oxygen in the lungs, enabling effective transport to tissues where oxygen is released for cellular respiration.

(b) White Blood Cells (WBCs) in Phagocytosis and Antibody Production

• Phagocytosis: Certain white blood cells, particularly phagocytes like neutrophils and macrophages, perform phagocytosis. They engulf and digest pathogens such as bacteria and dead cells. This non-specific immune response helps eliminate infections and clear debris from tissues.
• Antibody Production: Lymphocytes, a type of white blood cell, are responsible for producing antibodies. These proteins specifically target antigens on pathogens, marking them for destruction or neutralization. This specific immune response is crucial for long-term immunity and fighting off infections .

(c) Platelets in Clotting

• Function: Platelets are essential for blood clotting (coagulation). When a blood vessel is injured, platelets quickly adhere to the site of damage and aggregate to form a temporary plug that seals the wound. They also release chemicals that attract more platelets and initiate the clotting cascade, which ultimately leads to the formation of a stable fibrin clot that prevents excessive bleeding .

(d) Plasma in Transport

• Function: Plasma is the liquid component of blood that serves multiple transport functions:
  • Transport of Blood Cells: It carries red blood cells, white blood cells, and platelets throughout the circulatory system.
  • Ions: Plasma transports essential ions such as sodium, potassium, calcium, and bicarbonate, which are vital for various physiological processes.
  • Nutrients: It carries nutrients absorbed from digestion (like glucose and amino acids) to cells for energy and growth.
  • Urea: Plasma transports waste products like urea from metabolism to the kidneys for excretion.
  • Hormones: It carries hormones from endocrine glands to target organs, facilitating communication within the body.
  • Carbon Dioxide: Plasma transports carbon dioxide from tissues back to the lungs for exhalation