A young man happens to spot an ex-girlfriend he’s trying to avoid. Why does his mouth
become dry?
A. His cervical plexus overrides the parasympathetic stimulation for saliva production.
B. His cranial nerves shut down saliva production.
C. His central nervous system shuts down saliva production.
D. His sympathetic nervous system overrides the parasympathetic stimulation for
saliva production.
The correct answer is D. His sympathetic nervous system overrides the parasympathetic stimulation for saliva production.
When a person is faced with a stressful or alarming situation, their sympathetic nervous system is activated. This triggers the "fight or flight" response, which includes a variety of physiological changes in the body. One of these changes is the suppression of saliva production.
To further explain how to arrive at this answer, let's break it down:
Option A, "His cervical plexus overrides the parasympathetic stimulation for saliva production," is not the correct answer. The cervical plexus is not directly involved in regulating saliva production.
Option B, "His cranial nerves shut down saliva production," is also incorrect. While the cranial nerves play a role in the control of salivation, they do not shut down saliva production in this particular situation.
Option C, "His central nervous system shuts down saliva production," is not the correct answer either. While the central nervous system does coordinate the overall regulation of saliva production, it does not actively shut it down in this scenario.
Option D, "His sympathetic nervous system overrides the parasympathetic stimulation for saliva production," is the correct answer. In times of stress or fear, the sympathetic nervous system takes over and dampens the activity of the parasympathetic nervous system, which is responsible for stimulating saliva production. As a result, saliva production is reduced, leading to a dry mouth sensation.
So, in this case, the young man's mouth becomes dry because his sympathetic nervous system overrides the parasympathetic stimulation for saliva production.