This focuses on the role of neurotransmitters in the involuntary functions of the body regulated by the autonomic nervous system.
The three main neurotransmitters discussed are
acetylcholine, norepinephrine, and epinephrine.
Any given junction in the autonomic nervous system uses only one of these transmitter substances. A fourth compound, dopamine, may also serve as a transmitter, but this role has not been demonstrated conclusively.
In order to understand the mechanism of action of drugs that act upon these neurotransmitters, it is necessary to know the identity of the transmitter employed at each of the junctions of the autonomic nervous
system
Acetylcholine is the chemical transmitter employed at most junctions of the ANS as well as at the skeletal muscles. Acetylcholine is the transmitter
released by:
1. All preganglionic neurons of the PNS
2. All preganglionic neurons of the SNS
3. All postganglionic neurons of the PNS
4. Most postganglionic neurons of the SNS that go to sweat glands
5. All motor neurons to skeletal muscles
Norepinephrine is the chemical transmitter released by all postganglionic neurons of the SNS. Th e only exceptions are the postganglionic sympathetic neurons that go to sweat glands, which employ acetylcholine as
their transmitter.
Epinephrine is a major transmitter released by the adrenal medulla.
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