The phrenic nerve fires.Which event occurs next?
A)The inspiratory neurons fire.
B)The diaphragm contracts.
C)Air moves into the lungs.
D)Thoracic volume decreases.

Question

Quizplus · Accepted Answer

The phrenic nerve stimulates the contraction of the diaphragm, which is the muscle responsible for most of the air movement during breathing. Therefore, choice B is the correct answer. Once the diaphragm contracts, it creates a vacuum that pulls air into the lungs, and the thoracic volume increases, not decreases (eliminating choice D). The firing of inspiratory neurons is a result of the contraction of the diaphragm, which leads to the expansion of the lungs and the intake of air, so choice A would occur after choice B.

The Phrenic Nerve Fires.Which Event Occurs Next