When the diaphragm contracts,
A)the volume of the thoracic cavity increases
B)lung volume increases as the lungs are forced to expand
C)the intra-alveolar pressure increases
D)both a and b occur
E)a, b, and c occur

Question

Quizplus · Accepted Answer

When the diaphragm contracts, it moves downward, which causes the volume of the thoracic cavity to increase. As a result, the lungs are forced to expand, which increases their volume. However, as the lung volume increases, the intra-alveolar pressure decreases (Boyle's law). Therefore, both options A and B are correct, but option C is incorrect.

When the Diaphragm Contracts