When the muscles of respiration relax,
A)thoracic volume decreases and air moves out of the lungs.
B)thoracic volume increases and air moves out of the lung.
C)thoracic volume decreases and air moves into the lungs.
D)thoracic volume decreases and intrapulmonic pressure decreases.

Question

Quizplus · Accepted Answer

When the muscles of respiration relax, the thoracic volume decreases, creating a decrease in the space within the lungs. This causes an increase in intrapulmonic pressure, which pushes air out of the lungs during exhalation. Therefore, the correct answer is A.

When the Muscles of Respiration Relax