The Phrenic Nerve Fires.Which Event Occurs Next

Question

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.

Accepted Answer

The firing of the phrenic nerve signals the diaphragm to contract, which then causes a decrease in pressure within the thoracic cavity and allows air to move into the lungs. The inspiratory neurons firing and a decrease in thoracic volume are also important events in the process of breathing, but they occur after the diaphragm contracts.