When the diaphragm and external intercostal muscles contract,
A) the volume of the thorax increases.
B) the volume of the thorax decreases.
C) the volume of the lungs decreases.
D) the lungs collapse.
E) expiration occurs.

Question

Quizplus · Accepted Answer

When the diaphragm and external intercostal muscles contract, the thoracic cavity expands, increasing the volume of the thorax. This expansion creates a negative pressure gradient that allows air to be drawn into the lungs. This process is called inspiration.

When the Diaphragm and External Intercostal Muscles Contract