Question

Lungs ventilation movements is due to

• A. Costal muscle and diaphragm
• B. Costal muscle
• C. Diaphragm
• D. Wall of the lungs

Answer 1

The correct option is A Costal muscle and diaphragm

Breathing involves two stages, inspiration during which atmospheric air is drawn in and expiration by which the alveolar air is released out. The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere. Inspiration can occur if the pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure, i.e., there is a negative pressure in the lungs with respect to atmospheric pressure. Similarly, expiration takes place when the intra-pulmonary pressure is higher than the atmospheric pressure. The diaphragm and a specialised set of muscles external and internal intercostals between the ribs, help in generation of such gradients.

Therefore, the correct answer is option A.