Question

Acetylcholine is always the neurotransmitter employed by each of the following EXCEPT

A) parasympathetic preganglionic neurons.

B) parasympathetic postganglionic neurons.

C) sympathetic preganglionic neurons.

D) sympathetic postganglionic neurons.

Answer 1

All preganglionic fibers release ACh, but postganglionic sympathetic neurons do not employ acetylcholine as their neurotransmitter.

Step-by-step explanation:

All preganglionic fibers, both sympathetic and parasympathetic, release ACh. All ganglionic neurons-the targets of these preganglionic fibers-have nicotinic receptors in their cell membranes. The postganglionic parasympathetic fibers also release ACh, but the receptors on their targets are muscarinic receptors, which are G protein-coupled receptors and do not exclusively cause depolarization of the postsynaptic membrane. Postganglionic sympathetic fibers release norepinephrine, except for fibers that project to sweat glands and to blood vessels associated with skeletal muscles, which release ACh.