Question

What are the mechanics of breathing?

Answer 1

Breathing:

1. Breathing refers to the process in which atmospheric O₂ is exchanged with CO₂ that is produced by the cells in the body.
2. It is carried out by different respiratory organs.

Mechanics of breathing:

1. The process of breathing involves two phases- ‘inspiration’ in which atmospheric air enters the lungs and ‘expiration’ in which alveolar air is expelled.
2. Inspiration takes place when the intra-pulmonary pressure is less than the atmospheric pressure.
3. It is initiated by the diaphragm contraction which increases the volume of the thoracic cavity.
4. The external intercostal muscles start contracting which further increases the volume of the thoracic cavity.
5. Simultaneously, there is an increase in pulmonary volume which decreases the intra-pulmonary pressure. As a result, the atmospheric air moves into the lungs.
6. During expiration, the diaphragm and external intercostal muscles relax.
7. The internal intercostal muscles start contracting and the volume of the thoracic cavity is reduced.
8. The intra-pulmonary pressure is slightly increased with respect to the atmospheric pressure, resulting in an expulsion of air from the lungs.