Yawning is a modified respiratory movement that
A)involves relaxation of the external intercostal muscles.
B)involves contraction of the abdominal muscles.
C)is stimulated by irritation of the nasal mucosa.
D)involves spasmodic closure of the larynx.
E)involves a smooth extended contraction of the diaphragm.

Question

Quizplus · Accepted Answer

Yawning involves a smooth extended contraction of the diaphragm, which causes a deep inhalation of air. This is followed by a slow exhalation, often accompanied by vocalization or stretching. Other respiratory muscles, such as the external intercostals and abdominal muscles, may also be involved in the process, but the diaphragm is the primary muscle responsible for the deep inhalation that characterizes yawning. Irritation of the nasal mucosa and spasmodic closure of the larynx are not typically involved in yawning.

Yawning Is a Modified Respiratory Movement That