Question

Describe how oxygen and carbon dioxide are carried in the blood, and explain the role of hemoglobin.

Answer 1

Transportation of oxygen in the blood-

Only 1.5% of oxygen dissolves in the blood directly and it is transported to the tissues.

98.5% of oxygen binds to the protein present in the hemoglobin of red blood cells and transported to the tissues.

Hemoglobin is a pigment that composed of central heme part surrounded by 4 globin (protein) molecules. Each protein molecule can bind one oxygen molecule. So that one hemoglobin can transport 4 oxygen molecules.

Transportation of carbon dioxide in the blood:-

Carbon dioxide in blood can be transported through various paths. They are as below:-

• Carbon dioxide is more soluble in blood than oxygen. Near by 5-7% of carbon dioxide from the tissues are transported to the lungs through dissolution in the blood.
• 10% of carbon dioxide is transported through binding to the hemoglobin.
• Majority of carbon dioxide (85%) molecules are carried in the blood through blood buffer system.
  • When the carbon dioxide diffuses into red blood cells.
  • In the RBCs, Carbonic anhydrase (CA) quickly converts the carbon dioxide into carbonic acid (H2CO3).
  • Carbonic acid is an unstable, intermediate molecule that immediately dissociates into bicarbonate ions (HCO3−) and hydrogen (H+) ions
  • This bicarbonate molecules are disassociate after reaching the lungs.

Hemoglobin plays a major role in transportation of oxygen and minor role in transportation of carbon dioxide.