From Lungs To Tissues: Understanding Oxygen Transport In Blood

From Lungs To Tissues: Understanding Oxygen Transport In Blood

With the help of labelled diagram of oxygen-haemoglobin dissociation curve, explain the transport of oxygen from the lungs to the tissues. Give two factors shifting this curve to the right and significance of such shift.
Answer:

Shifting of curve towards right:

Oxygen-Haemoglobin Dissociation Curve Significance:

• Indicates dissociation of oxygen from haemoglobin.
• It signifies that as the oxygen content held by the blood decreases, it causes dissociation of oxygen.

Oxygen-Haemoglobin Dissociation Curve Effecting:

1. Partial pressure of gases:

• Decrease in partial pressure of oxygen causes this shift.
• While increases in partial pressure of carbon dioxide causes this shift.

2. Blood pH:

• Fall in blood pH occurring due to
  1. Increases in Co₂ content.
  2. Increase of H ion concentration.
  3. Presence of any acid in blood.
• All these shifts the curve towards right.

3. Body temperature:

Increase in body temperature shifts the curve towards right.

4. 2, 3, diphophoglyceric acid (2, 3. DPG):

• 2,3 DPG competes with oxygen for the binding sites on the haemoglobin molecule.
• Thus, at a given pO₂ the percentage saturation of haemoglobin with O₂ will be reduced in the presence of 2, 3. DPG.
• So, the curve shifts to right.
• DPG increases during exercise and in high altitude.