What neurotransmitter is released by the parasympathetic system?

What neurotransmitter is released by the parasympathetic system?

• A. Dopamine
• B. GABA
• C. Acetylcholine
• D. Norepinephrine

Answer: (C)

The transmitter used by the parasympathetic system is acetylcholine. In this division, both preganglionic and postganglionic neurons release acetylcholine, so signaling in parasympathetic pathways is cholinergic. Acetylcholine acts on nicotinic receptors in the autonomic ganglia and on muscarinic receptors on target organs, producing the characteristic rest-and-digest effects such as slowed heart rate and increased digestion. Dopamine and GABA aren’t the primary autonomic transmitters—their roles are different within the CNS and other pathways. Norepinephrine is the main transmitter of the sympathetic postganglionic fibers, not the parasympathetic ones. (An exception to remember: some sympathetic fibers, like those to sweat glands, use acetylcholine, but that doesn’t change the general parasympathetic transmitter.)

The transmitter used by the parasympathetic system is acetylcholine. In this division, both preganglionic and postganglionic neurons release acetylcholine, so signaling in parasympathetic pathways is cholinergic. Acetylcholine acts on nicotinic receptors in the autonomic ganglia and on muscarinic receptors on target organs, producing the characteristic rest-and-digest effects such as slowed heart rate and increased digestion.

Dopamine and GABA aren’t the primary autonomic transmitters—their roles are different within the CNS and other pathways. Norepinephrine is the main transmitter of the sympathetic postganglionic fibers, not the parasympathetic ones. (An exception to remember: some sympathetic fibers, like those to sweat glands, use acetylcholine, but that doesn’t change the general parasympathetic transmitter.)