Question

Explain the process of breathing in human beings.

Answer 1

Breathing:

The inhalation (move-in) and exhalation (move-out) of air through the lungs is known as breathing.

Breathing mechanism:

The breathing mechanism involves two major steps.

A. Inspiration or inhalation:

1. The external intercostal muscles located on the outer side of the rib cage pull to bring about the expansion of the chest cavity via elevating the ribs.
2. The diaphragm located beneath the lungs moves downward via contraction thus further expanding the thoracic cavity.
3. The contraction of the diaphragm leads to the contraction of abdominal muscles, hence allowing air to rush inside the expanded chest cavity.

B. Expiration or exhalation:

1. This process involves the expulsion of air outside the lungs.
2. The internal intercostal muscles attached to the inner side of the ribs force out the air by depressing down the rib cage.
3. The diaphragm and the abdominal muscles relax to decrease the volume of the thoracic cavity, this leads to increased pressure inside the lungs.
4. Hence, the increased pressure causes the air present inside the lungs to move out.

The process of breathing helps in the exchange of gases, i.e. oxygen and carbon dioxide from the lungs.