Sympathetic nerves release the neurotransmitter _______, which speeds the heart rate and increases the strength of contraction.
A) epinephrine
B) norepinephrine
C) acetylcholine
D) Purkinje

Question

Quizplus · Accepted Answer

Sympathetic nerves release norepinephrine, which acts on beta-adrenergic receptors in the heart to increase heart rate and contractility. Epinephrine is also released by the sympathetic nervous system and has similar effects, but norepinephrine is the primary neurotransmitter involved in sympathetic stimulation of the heart. Acetylcholine, on the other hand, is the primary neurotransmitter released by the parasympathetic nervous system and serves to slow the heart rate and decrease contractility. Purkinje fibers are specialized cardiac muscle fibers involved in the conduction of electrical signals through the heart.

Sympathetic Nerves Release the Neurotransmitter _______, Which Speeds the Heart