Question

When you hold your breath, which of the following gas changes in the blood leads to an urge to breathe?

• A. falling oxygen concentration
• B. rising carbon dioxide and falling oxygen concentration
• C. falling carbon dioxide concentration
• D. rising carbon dioxide concentration

Answer 1

The correct option is D

rising carbon dioxide concentration

The correct answer is option D.

Explanation of the correct answer:

1. When we hold our breath, the amount of CO₂ in the body increases.
2. This may lead to a change in the pH of the blood.
3. The changing pH is detected by the chemoreceptors in the blood vessels.
4. This activates the respiratory center of the brain which in turn signals the muscles of respiratory organs.
5. This leads to an urge to release our hold and breathe.

Thus, the final answer is a rising carbon dioxide concentration.