What Causes the Change in Pressure Needed for Normal Quiet

Question

What causes the change in pressure needed for normal quiet expiration?
A) Contraction of the diaphragm
B) Contraction of the external intercostal muscles
C) Elastic recoil of the lungs
D) Dilation of the bronchial tree

Accepted Answer

Elastic recoil of the lungs is responsible for the change in pressure needed for normal quiet expiration. This is a passive process where the lungs return to their resting state after being stretched during inhalation, increasing the pressure in the thoracic cavity and pushing air out.