Question

During inspiration the diaphragm

• A. Relaxes to become dome-shaped
• B. Contracts and flattens
• C. Shows no change
• D. Expands

Answer 1

The correct option is B

Contracts and flattens

The correct option is (B) :

Explanation of the correct option:

1. The diaphragm contracts and flattens during inspiration to increase the volume of the thoracic cavity.
2. The increase in volume causes a decrease in intra-alveolar pressure, pressure lower than the atmospheric pressure, and creates a pressure gradient.
3. Because of this gradient air from the atmosphere is forced inside the lungs through the nasal cavity.

Explanation of the incorrect options:

Option (A)

The diaphragm relaxes to become dome-shaped upon exhalation.

Option (C):

The diaphragm shows no change in structure when any respiratory disease occurs.

Option (D):

Not the diaphragm, but the thoracic cavity expands upon inspiration.

Final answer: During inspiration the diaphragm contracts and flattens.