While walking down the street, a cat jumps out of an alley into the pathway of an adult. They note that his heart is "racing." This response is primarily due to:

Question

A) Reflex circuitry produced by the ANS reflexes
B) Parasympathetic effects on the vagus nerve
C) Secretions of sympathetic neurotransmitters produced in the adrenal medulla
D) The cell body of the first motor neuron that lies in the brain stem

Answer 1

Ans: A
Feedback:
The organization of many life-support reflexes occurs in the reticular formation of the medulla and pons. These areas of reflex circuitry, often called centers, produce complex combinations of autonomic and somatic efferent functions required for the cough, sneeze, swallow, and vomit reflexes, as well as for the more purely autonomic control of the cardiovascular system. One of the striking features of ANS function is the rapidity and intensity with which it can change visceral function. Within 3 to 5 seconds, it can increase heart rate to approximately twice its resting level. The vagus nerve provides parasympathetic innervation for the heart, trachea, lungs, esophagus, etc. The adrenal medulla, which is part of the sympathetic nervous system, contains postganglionic sympathetic neurons that secrete sympathetic neurotransmitters directly into the bloodstream. The cell body of the first motor neuron, called the preganglionic neuron, lies in the brain stem or the spinal cord.