Question

Forced deep breathing for a few minutes by a person sitting at rest may be
followed by a temporary cessation of breathing. This is due to:

• A. Too much $O_2$ in the blood
• B. Too much $C{O}_2$ in the blood
• C. Very little $C{O}_2$ in the blood
• D. Both too much $O_2$ and very little $C{O}_2$ in the blood

Answer 1

The correct option is D Both too much $O_2$ and very little $C{O}_2$ in the blood

Deep breathing rises the $O_2$ level of the blood. By excess formation of oxyhaemoglobin the acidity of blood increases. To control it, more of free $C{O}_2$ changes into bicarbonates and the free $C{O}_2$ level in the blood decreases. So due to lack of stimulant for inspiratory centre cessation of breathing takes place, after some time $O_2$ is consumed by the tissues and rise in $C{O}_2$ stimulates breathing again. So, the correct answer is 'Both too much O${}_2$ and very little CO${}_2$ in the blood'.