Which of the Following Occurs on Exhalation

Question

Which of the following occurs on exhalation?
A) Respiratory expiratory neurons fire.
B) The diaphragm relaxes.
C) Thoracic volume decreases.
D) All of the above occur.

Accepted Answer

During exhalation, respiratory expiratory neurons fire, causing contraction of the abdominal muscles and intercostal muscles to push air out of the lungs. The diaphragm relaxes, moving upward into the thoracic cavity. This, combined with the contraction of the intercostal muscles, causes a decrease in thoracic volume, which helps to push air out of the lungs. Therefore, all of the above occur during exhalation.