Enteric nervous system
193757
224085911
2008-07-07T06:33:55Z
Ckatz
831038
rv. - per [[WP:V]] and [[WP:RS]], web blogs are not considered to be reliable sources for citing information
[[Image:ens.png|thumb|300px|The enteric nervous system is embedded in the lining of the [[gastrointestinal system]].]]
The '''enteric nervous system''' ('''ENS''') is a subdivision of the [[Peripheral Nervous System]], that directly controls the [[gastrointestinal system]]. It is capable of autonomous functions such as the coordination of [[reflex]]es, although it receives considerable innervation from the [[autonomic nervous system]] and thus is often considered a part of it. Its study is the focus of [[neurogastroenterology]]. It has as many as one billion neurons, one hundredth of the number of neurons in the [[brain]], and considerably more than the number of neurons in the [[spinal cord]]. The enteric nervous system is embedded in the lining of the [[gastrointestinal system]].
==Layers==
The neurons of the ENS are collected into two types of [[ganglia]]: [[myenteric plexus|myenteric (Auerbach's)]] and [[submucosal plexus|submucosal (Meissner's) plexuses]]. Myenteric plexuses are located between the inner and outer layers of the [[muscularis externa]], while submucosal plexuses are located in the [[submucosa]].
==Complexity==
There are several reasons why the enteric nervous system may be regarded as a second brain. The enteric nervous system can operate autonomously. It normally communicates with the CNS through the [[parasympathetic nervous system|parasympathetic]] (eg, via the [[vagus nerve]]) and [[sympathetic nervous system|sympathetic]] (eg, via the [[prevertebral ganglia]]) nervous systems. However, [[vertebrate]] studies show that when the vagus nerve is severed, the enteric nervous system continues to function.
The complexity of the enteric nervous system is another reason for its status as a second brain. In vertebrates the enteric nervous system includes [[efferent neurons]], [[afferent neuron]]s, and [[interneurons]], all of which make the enteric nervous system capable of carrying reflexes in the absence of CNS input. The sensory neurons report on mechanical and chemical conditions. Through intestinal muscles, the motor neurons control [[peristalsis]] and churning of intestinal contents. Other neurons control the secretion of [[enzymes]]. The enteric nervous system also makes use of the same [[neurotransmitters]] as the CNS, such as [[acetylcholine]], [[dopamine]], and [[serotonin]]. The enteric nervous system has the capacity to alter its response depending on such factors as bulk and nutrient composition.
==References==
*[[The Second Brain]] by Dr. [[Michael D. Gershon]]
*[http://www.anaesthetist.com/anaes/patient/ans/ens.htm "The Enteric nervous system (ENS)" at anaesthetist.com]
*{{cite journal | author = Saffrey M | title = Ageing of the enteric nervous system. | journal = Mech Ageing Dev | volume = 125 | issue = 12 | pages = 899–906 | year = 2004 | pmid = 15563936 | doi = 10.1016/j.mad.2004.09.003}} [http://www.open.ac.uk/science/biosci/research/saffrey/saffrey.htm Link]
* {{cite journal | author = Grundy D, Schemann M | title = Enteric nervous system | journal = Curr Opin Gastroenterol | volume = 22 | issue = 2 | pages = 102–10 | year = 2006 | pmid = 16462164 | doi = 10.1097/01.mog.0000208459.46395.16}} [http://www.medscape.com/viewarticle/524224 Link]
*Furness JB (2006) The Enteric Nervous System. Blackwell, Oxford, pp 274
==External links==
* {{GeorgiaPhysiology|6/6ch2/s6ch2_29}}
==Additional images==
<gallery>
Image:Gray1071.png|The myenteric plexus from the rabbit. X 50.
Image:Gray1072.png|The plexus of the submucosa from the rabbit. X 50.
</gallery>
{{Gastrointestinal physiology}}
[[Category:Enteric nervous system|*]]
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[[fr:Système nerveux entérique]]
[[pt:Sistema nervoso entérico]]
[[simple:Enteric nervous system]]
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