During Quiet Breathing

Question

During quiet breathing,
A) only the internal intercostal muscles contract.
B) inspiration involves muscular contractions and expiration is passive.
C) inspiration is passive and expiration involves muscular contractions.
D) both inspiration and expiration are passive.
E) both inspiration and expiration involve muscular contractions.

Accepted Answer

During quiet breathing, inspiration involves the contraction of the diaphragm and external intercostal muscles to draw air into the lungs, while expiration is generally passive, relying on the relaxation of these muscles and the elastic recoil of the lungs to expel air.