Firing of the intercostal and phrenic nerves
A)activates the respiratory control center in the medulla oblongata.
B)causes relaxation of the muscles of respiration.
C)causes a skeletal muscle response that increases thoracic volume.
D)dilates the bronchioles.

Question

Quizplus · Accepted Answer

Firing of the intercostal and phrenic nerves causes a skeletal muscle response that increases thoracic volume, which is necessary for inspiration.

Answer: B 
 Relaxation of the muscles of respiration would decrease thoracic volume and decrease the ability to breathe. Therefore, this choice is not accurate.

Answer: D 
 Firing of the intercostal and phrenic nerves does not have any direct effect on bronchiole dilation or constriction, so this choice is not accurate.

Answer: A 
 Firing of the intercostal and phrenic nerves plays a role in breathing, but it is not the direct activator of respiratory control center in the medulla oblongata. Therefore, this choice is not accurate.

Firing of the Intercostal and Phrenic Nerves