Enteric nervous system

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Ens embedded in intestinal lining

The enteric nervous system (ENS) is an interdependent part of the autonomic nervous system. Despite its many interactions with other parts of the ANS, it can be regarded as a nerval body of its own. Its functioning is still subject to research in neurogastroenterology. It has as many as 1 billion neurons, one hundredth of the number of neurons in the brain.

1 Layers
2 Complexity of the enteric nervous system
3 Sources
4 External links
5 Additional images

[edit] Layers

The ENS is comprised of two layers:

One is the myenteric plexus that lies between the layers of circular and longitudinal muscle lining the gut wall.
The second is the submucosal plexus that is found between the layer of circular muscle and the submucosa.

[edit] Complexity of the enteric nervous system

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, sensory neurons, motor 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.

[edit] Sources

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