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In the [[autonomic nervous system]], fibers from the [[central nervous system|CNS]] to the [[autonomic ganglion|ganglion]] are known as '''preganglionic fibers'''. All preganglionic fibers, whether they are in the [[sympathetic nervous system|sympathetic division]] or in the [[parasympathetic nervous system|parasympathetic division]], are [[cholinergic]] (that is, these fibers use [[acetylcholine]] as their [[neurotransmitter]]) and they are [[myelin]]ated.
In the [[autonomic nervous system]], fibers from the [[central nervous system|CNS]] to the [[autonomic ganglion|ganglion]] are known as '''preganglionic fibers'''.


== Neruotransmitters ==
All preganglionic fibers in the [[parasympathetic nervous system|parasympathetic division]] are [[cholinergic]] (that is, these fibers use [[acetylcholine]] as their [[neurotransmitter]]), which is also true for their [[Postganglionic nerve fibers|postganglionic]] counterparts<ref>{{Cite journal|last=McCorry|first=Laurie Kelly|date=2007-08-15|title=Physiology of the Autonomic Nervous System|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1959222/|journal=American Journal of Pharmaceutical Education|volume=71|issue=4|issn=0002-9459|pmc=PMCPMC1959222|pmid=17786266}}</ref>. Those of the [[sympathetic division]] are [[Adrenergic nervous system|adrenergic]] (use [[noradrenaline]] as their neurotransmitter), except for the postganglionic [[Sudomotor|cutaneous sudomotor neurones]], which are cholinergic.<ref>{{Citation|title=Postganglionic nerve fibers|date=2018-11-27|url=https://en.wikipedia.org/enwiki/w/index.php?title=Postganglionic_nerve_fibers&oldid=870896821|work=Wikipedia|language=en|access-date=2019-04-21}}</ref> All preganglionic neurons are myelinated.
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== Sympathetic vs Parasympathetic ==
[[Sympathetic nervous system|Sympathetic]] preganglionic fibers tend to be shorter than parasympathetic preganglionic fibers because sympathetic ganglia are often closer to the spinal cord than are the [[Parasympathetic nervous system|parasympathetic]] ganglia. Another major difference between the two ANS (autonomic nervous systems) is divergence. Whereas in the parasympathetic division there is a divergence factor of roughly 1:4, in the sympathetic division there can be a divergence of up to 1:20. This is due to the number of synapses formed by the preganglionic fibers with ganglionic neurons.
[[Sympathetic nervous system|Sympathetic]] preganglionic fibers tend to be shorter than parasympathetic preganglionic fibers because sympathetic ganglia are often closer to the spinal cord than are the [[Parasympathetic nervous system|parasympathetic]] ganglia. Another major difference between the two ANS (autonomic nervous systems) is divergence. Whereas in the parasympathetic division there is a divergence factor of roughly 1:4, in the sympathetic division there can be a divergence of up to 1:20. This is due to the number of synapses formed by the preganglionic fibers with ganglionic neurons.


Revision as of 15:06, 21 April 2019

Preganglionic nerve fibers
Autonomic nervous system innervation, showing the sympathetic and parasympathetic (craniosacral) systems, in red and blue, respectively
Details
Identifiers
Latinneurofibrae preganglionicae
TA98A14.2.00.009
FMA76568
Anatomical terms of neuroanatomy

In the autonomic nervous system, fibers from the CNS to the ganglion are known as preganglionic fibers.

Neruotransmitters

All preganglionic fibers in the parasympathetic division are cholinergic (that is, these fibers use acetylcholine as their neurotransmitter), which is also true for their postganglionic counterparts[1]. Those of the sympathetic division are adrenergic (use noradrenaline as their neurotransmitter), except for the postganglionic cutaneous sudomotor neurones, which are cholinergic.[2] All preganglionic neurons are myelinated.

Sympathetic vs Parasympathetic

Sympathetic preganglionic fibers tend to be shorter than parasympathetic preganglionic fibers because sympathetic ganglia are often closer to the spinal cord than are the parasympathetic ganglia. Another major difference between the two ANS (autonomic nervous systems) is divergence. Whereas in the parasympathetic division there is a divergence factor of roughly 1:4, in the sympathetic division there can be a divergence of up to 1:20. This is due to the number of synapses formed by the preganglionic fibers with ganglionic neurons.

See also

References

  1. ^ McCorry, Laurie Kelly (2007-08-15). "Physiology of the Autonomic Nervous System". American Journal of Pharmaceutical Education. 71 (4). ISSN 0002-9459. PMC PMCPMC1959222. PMID 17786266. {{cite journal}}: Check |pmc= value (help)
  2. ^ "Postganglionic nerve fibers", Wikipedia, 2018-11-27, retrieved 2019-04-21


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