Question

Inspiration occurs when there is a negative pressure in the lungs with respect to atmospheric pressure. This negative pressure is achieved when
A. intrapulmonary pressure is less than the atmospheric pressure
B. Intrapulmonary pressure is greater than the atmospheric pressure
C. intrapulmonary pressure is equal to the atmospheric pressure
D. intrapleural pressure becomes more than the intra-alveolar pressure.

Answer 1

Correct Answer - A
Because of the pressure gradient between the lungs and the atmosphere, the air moves into and out of the lungs. Inspiration occurs 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.