The heart rate decreases in response to the arrival of
A) acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric oxide.
E) GABA.

Question

Quizplus · Accepted Answer

Acetylcholine is released by the parasympathetic nervous system and causes the heart rate to decrease.

Answer: B 
 Epinephrine is released by the sympathetic nervous system and causes the heart rate to increase.

Answer: C 
 Endorphins are opioids that can cause a decrease in pain perception, but they do not directly affect heart rate.

Answer: D 
 Nitric oxide is involved in vasodilation, but does not directly affect heart rate.

Answer: E 
 GABA is an inhibitory neurotransmitter in the brain, but does not directly affect heart rate.

The Heart Rate Decreases in Response to the Arrival of