A child was frightened by a large dog.The pupils of the child's eyes became dilated,and the heart and respiratory rates increased.These symptoms were caused by stimulation of:
A) the parasympathetic nervous system.
B) the sympathetic nervous system.
C) both the parasympathetic and the sympathetic nervous systems.
D) None of the above would account for the symptoms.

Question

Quizplus · Accepted Answer

The symptoms observed in the child (dilated pupils, increased heart and respiratory rates) are classic signs of the fight-or-flight response, which is triggered by the sympathetic nervous system. The parasympathetic nervous system, on the other hand, has the opposite effect and would not cause these symptoms. Therefore, choice B (the sympathetic nervous system) is the best answer.

A Child Was Frightened by a Large Dog