Understanding Gas Exchange: Hemoglobin, RBCs, And Blood Chemistry

Understanding Gas Exchange: Hemoglobin, RBCs, And Blood Chemistry

Discuss factors affecting transport and diffusion of gases.

Answer:

Factors Affecting Transport:

1. Transport of oxygen:

1. Amount of oxygen entering the lung.
2. Adequacy of pulmonary gas exchange.
3. Blood flow to the tissue.
   • It is increased by following factors.
     1. Increase in capillary density.
     2. Local arteriolar dilation.
4. Capacity of the blood to carry O₂.
   • Due to splenic contraction, RBC count is increased.
   • This, in turn, increases haemoglobin content.
   • More the haemoglobin, more the oxygen is combined with it and carried along the blood.

2. Transport of Co₂:

1. Blood oxygen content.
   1. In tissue capillaries, blood oxygen content decreases producing deoxygenated blood.
   2. As the oxygen content decreases, carbon dioxide increases.
   3. Thus, more Co₂ is transported.
   4. Similarly, in lung capillaries, blood oxygen content is more which decreases Co₂ content of blood.
   5. Thus, less Co₂ is transported.
2. Number of RBC present in the blood.
   1. From plasma, the carbon dioxide enters the RBCs.
   2. In the RBCs, carbon dioxide combines with water to form carbonic acid.
   3. This carbonic acid readily dissociates into bicarbonate and hydrogen ions.
   4. This increased concentration of bicarbonate inside the RBC causes diffusion of bicarbonate ions through the cells membrane into the plasma.
   5. Thus, more the RBC, more bicarbonate ions are diffuses.
   6. So, more carbon dioxide is transported as bicarbonate.
3. The amount of reduced Hb.
   1. Reduced Hb contains less O₂ content and more Co₂ content in blood.
   2. Thus, as the amount of reduced Hb increases, Co₂ content also increases.
   3. So, more Co₂ is transported.