In quiet breathing,
A) inspiration and expiration involve muscular contractions.
B) inspiration is passive and expiration involves muscular contractions.
C) inspiration involves muscular contractions and expiration is passive.
D) inspiration and expiration are both passive processes.
E) only the diaphragm is active during inhalation.

Question

Quizplus · Accepted Answer

Inspiration involves muscular contractions, primarily of the diaphragm and the external intercostal muscles, to increase the volume of the thoracic cavity, thereby reducing the pressure and drawing air into the lungs. Expiration during quiet breathing is generally passive, relying on the elastic recoil of the lungs and chest wall to decrease the thoracic volume and increase the pressure, pushing air out of the lungs.

In Quiet Breathing