Question

Choose the correct option-

A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This oxygen ___?

• A. Raises the pCO2 of blood to 75 mm of Hg
• B. Acts as a reserve during muscular exercise
• C. Is enough to keep oxyhaemoglobin saturation at 96%
• D. Helps in releasing more O2 to the epithelium tissues

Answer 1

The correct option is B

Acts as a reserve during muscular exercise

The correct option is D.

Explanation of correct option

1. Hemoglobin helps in transporting the maximum amount of oxygen.
2. A small quantity is also found dissolved in the plasma.
3. Around 25% of oxygen is used up by the cells whereas the remaining 75% remains unused.
4. During muscular exercise, this unused oxygen acts as a reserve.
5. The normal partial pressure of carbon dioxide in blood ranges between 35 and 45 mmHg.
6. A higher value indicates respiratory acidosis and hypoventilation.
7. Various factors like temperature, pH, other forms of hemoglobin, partial pressure of carbon dioxide, and 2,3-DPG concentration in RBCs influence oxyhemoglobin saturation and dissociation of oxygen from the hemoglobin.

Final answer:

A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This oxygen acts as a reserve during muscular exercise.