At the end of a normal expiration, when outward air flow has ceased,
A)Intra-alveolar pressure is less than atmospheric pressure.
B)Intra-alveolar pressure is greater than atmospheric pressure.
C)Intra-alveolar pressure is equal to atmospheric pressure.
D)Intrapleural pressure is greater than atmospheric pressure.
E)Intrapleural pressure is greater than intra-alveolar pressure.

Question

Quizplus · Accepted Answer

At the end of a normal expiration, the intra-alveolar pressure equals atmospheric pressure. During expiration, the thoracic cavity and lungs recoil back to their original position, causing a decrease in volume and an increase in intra-alveolar pressure. This pressure gradually equalizes with atmospheric pressure, resulting in a state of equilibrium at the end of expiration. Intrapleural pressure, on the other hand, remains lower than intra-alveolar pressure at all times, thus preventing collapse of the lungs.

At the End of a Normal Expiration, When Outward Air