Enteric Nervous System

Information about Enteric Nervous System

The enteric nervous system is embedded in the lining of the gastrointestinal system.

The enteric nervous system (ENS) is the part of the nervous system that directly controls the gastrointestinal system. It is capable of autonomous functions such as the coordination of reflexes, 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.

Layers

The neurons of the ENS are collected into two types of ganglia: myenteric (Auerbach's) and 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 (eg, via the vagus nerve) and 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 neurons, 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 book The Second Brain by Dr. Michael D. Gershon
"The Enteric nervous system (ENS)" at anaesthetist.com
Saffrey M (2004). "Ageing of the enteric nervous system.". Mech Ageing Dev 125 (12): 899-906. PMID 15563936. Link
Grundy D, Schemann M (2006). "Enteric nervous system". Curr Opin Gastroenterol 22 (2): 102-10. PMID 16462164. Link
Furness JB (2006) The Enteric Nervous System. Blackwell, Oxford, pp 274

External links

Physiology at MCG 6/6ch2/s6ch2_29

Additional images

The myenteric plexus from the rabbit. X 50.

The plexus of the submucosa from the rabbit. X 50.

• • [ e] Digestive system, physiology: gastrointestinal physiology
Enteric nervous system	Meissner's plexus - Auerbach's plexus
Exocrine	Chief cells (Pepsinogen) - Parietal cells (Gastric acid, Intrinsic factor) - Goblet cells (Mucus)
Endocrine/paracrine	G cells (gastrin), D cells (somatostatin) - ECL cells (Histamine) - enterogastrone: I cells (CCK), K cells (GIP), S cells (secretin)
Border	Brunner's glands - Paneth cells - Enterocytes
Fluids	Saliva - Bile - Intestinal juice - Gastric juice - Pancreatic juice
Processes	Swallowing - Vomiting - Peristalsis (Interstitial cell of Cajal) - Migrating motor complex - Borborygmus - Gastrocolic reflex - Segmentation contractions - Defecation

nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and also stops input from the senses, and initiates actions. Prominent parts of a nervous system include neurons and nerves, which are used in coordination.
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gastrointestinal tract (GI tract), also called the digestive tract, or the alimentary canal, is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients, and expels the remaining waste.
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ReFLEX is a wireless protocol developed by Motorola which is used for two-way paging. It is based on the one-way FLEX protocol and comes in two variants, ReFLEX25 and ReFLEX50. Later version 2.7 of the ReFLEX protocol was released. Devices compliant with ReFLEX 2.7.
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autonomic nervous system (ANS) (or visceral nervous system) is the part of the peripheral nervous system that acts as a control system, maintaining homeostasis in the body. These maintenance activities are primarily performed without conscious control or sensation.
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Neurogastroenterology is a research area in the field of Gastroenterology which regards interactions of the central nervous system (brain) and the gut - the so-called brain-gut axis.
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In animals, the brain or encephalon (Greek for "in the skull"), is the control center of the central nervous system, responsible for behavior. The brain is located in the head, protected by the skull and close to the primary sensory apparatus of vision, hearing,
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spinal chord is a thin, tubular bundle of nerves that is an extension of the central nervous system from the brain and is enclosed in and protected by the bony vertebral column.
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ganglion (pl. ganglia) is a tissue mass, which is composed mainly of somata and dendritic structures, which often interconnect with each other to form a complex system of ganglia known as a plexus.
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Part of the enteric nervous system, Auerbach's plexus (or myenteric plexus) exists between the longitudinal and circular layers of muscularis externa in the gastrointestinal tract and provides motor innervation to both layers and secretomotor innervation to the mucosa.
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plexus of the submucosa (Meissner's plexus, Submucous plexus, submucosal plexus) is derived, and is formed by branches which have perforated the circular muscular fibers.
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The muscular coat (or muscular layer, or muscular fibers, or muscularis propria, or muscularis externa) is a region of muscle in many organs in the vertebrate body, adjacent to the mucous membrane. It is responsible for gut movement such as peristalsis.
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In the gastrointestinal tract, the submucosa is the layer of loose connective tissue that supports the mucosa, as well as joins the mucosa to the bulk of underlying smooth muscle (fibers running circularly within layer of longitudinal muscle).
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parasympathetic nervous system (PSNS) is one of three divisions of the autonomic nervous system (ANS). The ANS -a subdivision of the peripheral nervous system (PNS)- is subdivided into the sympathetic (SNS), parasympathetic (PSNS) and enteric (bowels) nervous system (ENS).
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The vagus nerve (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem (within the medulla oblongata) and extends, through the jugular foramen, down below the head, to the
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The Sympathetic Nervous System (SNS) is a branch of the autonomic nervous system. It is always active at a basal level (called sympathetic tone) and becomes more active during times of stress.
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Prevertebral ganglia (or collateral ganglia) are sympathetic ganglia which lie between the sympathetic chain and the organ of supply. They are the site of relay of the preganglionic sympathetic fibres that supply abdominal and pelvic viscera.
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Vertebrata
Cuvier, 1812

Classes and Clades

See below
Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns.
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efferent nerves – otherwise known as motor or effector neurons – carry nerve impulses away from the central nervous system to effectors such as muscles or glands (and also the ciliated cells of the inner ear).
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afferent neurons--otherwise known as sensory or receptor neurons--carry nerve impulses from receptors or sense organs toward the central nervous system. This is the case vice versa as well. This term can also be used to describe relative connections between structures.
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An interneuron (also called relay neuron, association neuron or bipolar neuron) is a term used to describe a neuron which has two different common meanings.
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Peristalsis is the rhythmic contraction of smooth muscles to propel contents through the digestive tract. The word is derived from New Latin and comes from the Greek peristaltikos, peristaltic, from peristellein, "to wrap around," and stellein
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Enzymes are proteins that catalyze (i.e. accelerate) chemical reactions.^[1] In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, the products.
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Neurotransmitters are chemicals that are used to relay, amplify and modulate signals between a neuron and another cell. According to the prevailing beliefs of the 1960s, a chemical can be classified as a neurotransmitter if it meets the following conditions:

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The chemical compound acetylcholine, often abbreviated as ACh, was the first neurotransmitter to be identified. It is a chemical transmitter in both the peripheral nervous system (PNS) and central nervous system (CNS) in many organisms including humans.
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Dopamine is a hormone and neurotransmitter occurring in a wide variety of animals, including both vertebrates and invertebrates. In chemical structure, it is a phenethylamine.
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Serotonin (pronounced IPA: /ˌsɛrəˈtoʊnən/) (5-hydroxytryptamine, or 5-HT) is a monoamine neurotransmitter synthesized in serotonergic neurons in the central nervous system (CNS) and
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Dr. Michael D. Gershon is the author of The Second Brain and the chairman of the department of anatomy and cell biology at Columbia University.

Sources

New York Times

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Medical College of Georgia is the smallest of four research schools in the University System of Georgia (USG). MCG currently has 5 undergraduate and graduate schools on campus: The School of Medicine, School of Dentistry, School of Nursing, School of Allied Health, and Graduate
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The digestive system is the organ system that breaks down and absorbs nutrients that are essential for growth and maintenance. The digestive system includes the mouth, esophagus, stomach, pancreas, liver, gallbladder, duodenum, jejunum, ileum, (intestines), rectum, and anus.
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Human physiology is the science of the mechanical, physical, and biochemical functions of humans in good health, their organs, and the cells of which they are composed. The principal level of focus of physiology is at the level of organs and systems.
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