Editing Autonomic nervous system (section)

===Enteric nervous system===
{{Main|Enteric nervous system}}
====Development of the enteric nervous system====
The intricate process of enteric nervous system (ENS) development begins with the migration of cells from the vagal section of the neural crest. These cells embark on a journey from the cranial region to populate the entire gastrointestinal tract. Concurrently, the sacral section of the neural crest provides an additional layer of complexity by contributing input to the hindgut ganglia. Throughout this developmental journey, numerous receptors exhibiting tyrosine kinase activity, such as Ret and Kit, play indispensable roles. Ret, for instance, plays a critical role in the formation of enteric ganglia derived from cells known as vagal neural crest. In mice, targeted disruption of the RET gene results in renal agenesis and the absence of enteric ganglia, while in humans, mutations in the RET gene are associated with megacolon. Similarly, Kit, another receptor with tyrosine kinase activity, is implicated in Cajal interstitial cell formation, influencing the spontaneous, rhythmic, electrical excitatory activity known as slow waves in the gastrointestinal tract. Understanding the molecular intricacies of these receptors provides crucial insights into the delicate orchestration of ENS development.<ref>{{Cite journal |last1=Goyal |first1=Raj K. |last2=Hirano |first2=Ikuo |date=1996-04-25 |title=The Enteric Nervous System |url=http://dx.doi.org/10.1056/nejm199604253341707 |journal=New England Journal of Medicine |volume=334 |issue=17 |pages=1106–1115 |doi=10.1056/nejm199604253341707 |pmid=8598871 |issn=0028-4793|url-access=subscription }}</ref>

====Structure of the enteric nervous system====
Originally perceived as postganglionic parasympathetic neurons, the ENS earned recognition for its autonomy in the early 1900s. Boasting approximately 100 million neurons, a quantity comparable to the spinal cord, the ENS is often described as a "brain of its own." This description is rooted in the ENS's ability to communicate independently with the central nervous system through parasympathetic and sympathetic neurons. At the core of this structure are the myenteric plexus (Auerbach's) and the submucous plexus (Meissner's), two main plexuses formed by the grouping of nerve-cell bodies into tiny ganglia connected by bundles of nerve processes. The myenteric plexus extends the full length of the gut, situated between the circular and longitudinal muscle layers. Beyond its primary motor and secretomotor functions, the myenteric plexus exhibits projections to submucosal ganglia and enteric ganglia in the pancreas and gallbladder. Additionally, the myenteric plexus plays a unique role in innervating motor end plates with the inhibitory neurotransmitter nitric oxide in the striated-muscle segment of the esophagus, a feature exclusive to this organ. Meanwhile, the submucous plexus, most developed in the small intestine, occupies a crucial position in secretory regulation. Positioned in the submucosa between the circular muscle layer and the muscularis mucosa, the submucous plexus's neurons innervate intestinal endocrine cells, submucosal blood arteries, and the muscularis mucosa. Furthermore, the ENS also has ganglionated plexuses in the pancreatic, cystic duct, common bile duct, and gallbladder, resembling submucous plexuses. Glial cells are also involved , outnumbering enteric neurons and covering the majority of the surface of enteric neuronal-cell bodies with laminar extensions. Resembling the astrocytes of the central nervous system, enteric glial cells respond to cytokines by expressing MHC class II antigens and generating interleukins. Thus, they have a pivotal role in modulating inflammatory responses in the intestine. The varied morphological shapes of enteric neurons further contribute to the structural diversity of the ENS, with neurons capable of exhibiting up to eight different morphologies. These neurons are primarily categorized into type I and type II, where type II neurons are multipolar with numerous long, smooth processes, and type I neurons feature numerous club-shaped processes along with a single long, slender process. <ref>{{Cite journal |last1=Goyal |first1=Raj K. |last2=Hirano |first2=Ikuo |date=1996-04-25 |title=The Enteric Nervous System |url=http://dx.doi.org/10.1056/nejm199604253341707 |journal=New England Journal of Medicine |volume=334 |issue=17 |pages=1106–1115 |doi=10.1056/nejm199604253341707 |pmid=8598871 |issn=0028-4793|url-access=subscription }}</ref>