Which statement is correct when outward airflow has ceased at the end of a normal expiration?
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.

Question

Quizplus · Accepted Answer

At the end of a typical expiration, the diaphragm and external intercostal muscles both relax causing the volume of the thoracic cavity to decrease. This causes the intra-alveolar pressure to become equalized with atmospheric pressure, resulting in a cessation of airflow. Therefore, intra-alveolar pressure is equal to atmospheric pressure. Intrapleural pressure is always less than atmospheric pressure, and the other options are also incorrect.

Which Statement Is Correct When Outward Airflow Has Ceased at the End