Question

A person sitting at rest experiences a temporary cessation of breathing after forced deep breathing for a few minutes. This is due to

• A. too much $CO_{2}$ in the blood
• B. too much $O_{2}$ in the blood
• C. very little $CO_{2}$ in the blood
• D. both high $O_{2}$ and very little $CO_{2}$ in the blood

Answer 1

Answer: (D)

Deep breathing rises the $O _{2}$ level of the blood. Acidity of blood increases due to excess formation of oxyhaemoglobin.
To maintain $pH$, more free $CO _{2}$ changes to bicarbonates and free $CO _{2}$ level in blood decreases. The lack of stimulant for inspiratory center, cessation of breathing occurs.