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	~~'''~~Preganglionic nerve fibers''' are a type of [[nerve fiber]] that originate in the [[central nervous system]] and extend to a [[ganglion]]. They are part of the [[autonomic nervous system]], which controls involuntary body functions such as heart rate and digestion.		{{DISPLAYTITLE:Preganglionic Nerve Fibers}}

	== ~~Anatomy~~ ==		==Preganglionic Nerve Fibers==
			[[File:Gray839.png\|thumb\|right\|Diagram of the autonomic nervous system showing preganglionic nerve fibers.]]
			Preganglionic nerve fibers are a type of [[nerve fiber]] found in the [[autonomic nervous system]] (ANS). These fibers originate in the central nervous system (CNS) and extend to the autonomic ganglia, where they synapse with postganglionic neurons. Preganglionic fibers are crucial for transmitting signals from the CNS to the peripheral organs and tissues, thereby regulating involuntary physiological functions.

	Preganglionic nerve fibers are myelinated, ~~meaning~~ they are ~~covered in a fatty substance called~~ [[~~myelin~~]] ~~that helps speed up~~ the ~~transmission of nerve signals~~. ~~They~~ originate in the ~~brain or~~ spinal cord ~~and extend to a ganglion~~, ~~where~~ they ~~synapse with [[postganglionic nerve fibers]]~~.		==Structure==
			Preganglionic nerve fibers are typically myelinated, which allows for rapid transmission of nerve impulses. They arise from the [[spinal cord]] or the [[brainstem]], depending on whether they are part of the [[sympathetic nervous system]] or the [[parasympathetic nervous system]]. In the sympathetic division, preganglionic fibers originate in the thoracolumbar region of the spinal cord, while in the parasympathetic division, they originate in the craniosacral regions.

	== Function ==		==Function==
			The primary function of preganglionic nerve fibers is to convey neural signals from the CNS to the autonomic ganglia. In the ganglia, these fibers release the neurotransmitter [[acetylcholine]], which binds to nicotinic receptors on the postganglionic neurons. This synaptic transmission is essential for the activation of postganglionic fibers, which then innervate target organs and tissues, modulating functions such as heart rate, digestion, and respiratory rate.

	~~The primary function of preganglionic nerve~~ fibers ~~is to transmit signals from~~ the ~~central~~ nervous system to the ~~ganglion~~. ~~From there~~, the ~~signal is carried on by postganglionic nerve~~ fibers to the ~~target organ~~ or ~~tissue. This allows the autonomic nervous system to regulate involuntary body functions~~.		==Sympathetic vs. Parasympathetic Fibers==
			Preganglionic fibers in the sympathetic nervous system are generally shorter than those in the parasympathetic system. This is because sympathetic ganglia are located closer to the spinal cord, whereas parasympathetic ganglia are located near or within the target organs. Consequently, the length and distribution of preganglionic fibers differ between these two divisions, reflecting their distinct roles in the "fight or flight" and "rest and digest" responses, respectively.

	== Clinical ~~significance~~ ==		==Clinical Significance==
			Disorders affecting preganglionic nerve fibers can lead to a variety of autonomic dysfunctions. For example, damage to these fibers can result in conditions such as [[Horner's syndrome]], characterized by ptosis, miosis, and anhidrosis. Understanding the pathways and functions of preganglionic fibers is crucial for diagnosing and treating autonomic nervous system disorders.
	~~Damage to~~ preganglionic nerve fibers can ~~result in~~ a variety of ~~symptoms, depending on the specific body function that is affected~~. For example, damage to fibers ~~that regulate heart rate~~ can result in [[~~arrhythmia~~]], ~~while damage to~~ fibers ~~that control digestion can lead to [[gastrointestinal~~ disorders]].

	~~== See also ==~~

			==Related pages==
			* [[Autonomic nervous system]]
			* [[Sympathetic nervous system]]
			* [[Parasympathetic nervous system]]
	* [[Nerve fiber]]		* [[Nerve fiber]]
	* [[~~Autonomic nervous system]]~~		* [[Acetylcholine]]
	* [[Postganglionic nerve fibers]]

	[[Category:Neuroanatomy]]		[[Category:Neuroanatomy]]
	~~[[Category:Nervous system]]~~
	~~[[Category:Medical terminology]]~~

	~~{{stub}}~~

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2024-02-23T13:17:04Z

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'''Preganglionic nerve fibers''' are a type of [[nerve fiber]] that originate in the [[central nervous system]] and extend to a [[ganglion]]. They are part of the [[autonomic nervous system]], which controls involuntary body functions such as heart rate and digestion.

== Anatomy ==

Preganglionic nerve fibers are myelinated, meaning they are covered in a fatty substance called [[myelin]] that helps speed up the transmission of nerve signals. They originate in the brain or spinal cord and extend to a ganglion, where they synapse with [[postganglionic nerve fibers]].

== Function ==

The primary function of preganglionic nerve fibers is to transmit signals from the central nervous system to the ganglion. From there, the signal is carried on by postganglionic nerve fibers to the target organ or tissue. This allows the autonomic nervous system to regulate involuntary body functions.

== Clinical significance ==

Damage to preganglionic nerve fibers can result in a variety of symptoms, depending on the specific body function that is affected. For example, damage to fibers that regulate heart rate can result in [[arrhythmia]], while damage to fibers that control digestion can lead to [[gastrointestinal disorders]].

== See also ==

* [[Nerve fiber]]
* [[Autonomic nervous system]]
* [[Postganglionic nerve fibers]]

[[Category:Neuroanatomy]]
[[Category:Nervous system]]
[[Category:Medical terminology]]

{{stub}}

Preganglionic nerve fibers - Revision history

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