Question

During expiration the diaphragm becomes
A. Dome-shaped
B. Oblique
C. Concave
D. Flattened

Answer 1

Hint: The breathing process is divided into inspiration and expiration. The diaphragm is located below the lungs. It is a very much important muscle involved in breathing in the process of respiration. During expiration, the diaphragm becomes relaxed, and the volume of the cavity becomes decreased, while the pressure increases. As a result, the lungs are contracted and the air is forced out.

Complete answer:
Breathing has two stages. In inspiration atmospheric air is stayed in and in expiration, the air is released out. When the pressure in the lungs, which is called the intrapulmonary pressure, gets lower than the atmospheric pressure, then inspiration occurs. And when intra pulmonary pressure is higher than the atmospheric pressure, expiration takes place. In inhalation, the diaphragm contracts and flattens, and the chest cavity gets enlarged. This contraction creates a vacuum. That pulls air into the lungs. In exhalation, the diaphragm relaxes and returns to its previous domelike shape. Then the air is forced out from the lungs. So the diaphragm becomes dome-shaped during expiration or exhalation.

The correct option is ‘A’ – Dome-shaped.

Additional information: We all have the ability to increase the strength of expiration and inspiration with the help of additional muscle in the abdomen. Commonly, a healthy and physically fit human can breathe 12-16 times per minute. Another important point is, the rhythm of the respiratory is maintained by the respiratory center in the medulla region of the brain.

Note:
Some important points to remember:
> Upon expiration, the lungs recoil to force the air out of the lungs.
> Upon expiration, the diaphragm relaxes and comes back to its dome-like shape, and the air is forced out of the lungs.
> The diaphragm squeezes downward when one breathes in.