Parasympathetic nervous system
Autonomic nervous system (ANS) consists of parasymphatetic nervous system (PSNS) and symphatetic nervous system (SNS). Parasympathetic nervous system is almost exclusively cholinergic, using acetylcholine (ACh) as the neurotransmitter.
Parasympathetic nerves arise from the central nervous system (CNS), mostly from the spinal cord. The efferent parasympathetic nerve signals are carried from the CNS to their targets by a system of two neurons: preganglionic (presynaptic) neuron and postganglionic (postsynaptic) neuron. The cell body of preganglionic neuron resides in the CNS, from where its long axons extend into a ganglion that is close to or embedded in the target organ. Accordingly, the postganglionic nerve fibres are short. The stimulated preganglionic neuron releases ACh at the ganglion, which acts on nicotinic acetylcholine receptors (nAChRs) of postganglionic neurons. The postganglionic neurons then releases ACh to stimulate the muscarinic acetylcholine receptors (mAChRs) of the target organ.
In pancreas, parasympathetic system stimulates insulin secretion, and sympathetic system stimulates glucagon secretion. Hypothalamus can regulate hepatic glucose production via PSNS.
- Cholinergic system
- Sympathetic nervous system
- Adrenergic system
- Renin-angiotensin-aldosterone system
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Tags: Autonomic nervous system, Acetylcholine, AChE, BuChE
Updated at: 2023-01-17
Created at: 2017-10-07
Written by: Vesa Oikonen