Question

Which of the following is not true about expiration?

• A. Diaphragm contracts during expiration
• B. The increased size of the thoracic cavity decreases the pressure inside
• C. Expiration begins when inspiration ends
• D. Expiration can either be voluntary or involuntary

Answer 1

The correct option is A

Diaphragm contracts during expiration

The correct option is option A.

The explanation for the correct option:

1. Expiration and inspiration are the two processes that take place in respiration.
2. During inspiration, the air is taken in while in expiration, the is taken out.
3. During expiration, the volume of the thoracic area decreases as the diaphragm became dome-shaped and the contraction of intercostal muscles.
4. Diaphragm and external respiratory muscles relax, elastic tissue of the lungs recoil and increases the intra-alveolar pressure, hence the air is forced out from the lungs.

Final answer: Diaphragm contracts during expiration is not true about expiration.