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GI tract and enteric nervous system

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GI tract and enteric nervous system

Postby snezka18 » Sun May 08, 2011 8:02 am

I am just wondering, enteric nervous system is part of autonomic nervous system right and it works together with parasympathetic and sympathetic branches?
But here it says in the GI tract it divides into submucosal nerve plexus and myonteric nerve plexus, so in that those 2 plexuses is there only the instrinct plexus- enteric nervous system?? that then works with the other part of autonomic (parasymp. and symp.)system in the spine and the brain
Or where would all those fibres synapse? what does synapse really mean, is it that the enteric nervous system then receives the message at that point?
:)
thanks
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Re: GI tract and enteric nervous system

Postby daniel.kurz » Fri Oct 28, 2011 6:31 am

This question always comes up and teachers never know how to get at it. Lets see if I can help to break this question up for you.

The peripheral nervous system is broken up into two systems the autonomic and the somatic.

The somatic we will leave at saying is responsible for all the outgoing signals to the body that relate to movement. This movement is called efferent pathway, moving out away from the central nervous system (CNS). It does not contain the other pathway going back to the CNS to send sensory information back, called afferent pathway.

The autonomic is more complex and contains both efferent and afferent pathways. Just to screw students up, researchers decided that they woulld split the autonomic system up into parasympathetic and sympathetic systems. Further they thought it would be a good idea to subdivide the autonomic system into more divisions. They devised the enteric nervous system. This is not to say that the enteric nervous, which is part of the autonomic system, does not contain both parasympathetic and sympathetic systems. The term enteric nervous system is simply a good easy way to classify the gut into its own nervous system. It really is just filled full of nerves and ganglia that help to regulate the huge amount of business down there.

Now, delving into what is an enteric system. Being part of the autonomic system that contains both efferent and afferent pathways, it must send and receive information. The sending is easy and it involves heading out a nerve making a jump to either the spinal cord via a synapse or to a cranial nerve through a synapse as well. Both occur!

The receiving of information can come down both pathways as well! Stimulation comes down through parasympathetic stimulation through the autonomic system to the enteric system via the tenth cranial nerve, called the vagus nerve. This pathway splits again in the enteric system into the myonteric (most people call it myenteric plexus) plexus and the submuscosal plexus (which further splits yet again). The myenteric system controls the large long smooth muscles that wrap around and along the intestine. There are extremely long smooth muscle that run the length of the intestine. Stimulating this gets motility (movement of food) going. The submucosal plexus does the same thing but in hierarchy it is lower on the list and controls fine movements through small muscle fiber groups in the intestine. Its similar to your big hamstrings in your leg swing your leg back and form. But there are tiny little muscles in the eye that move the eye in precision amounts.

The sympathetic system cuts this off which makes sense because in the heart the sympathetic system stimulates lots of nervous and high heart rate. Why would you want your gut extremely active when your body is getting all nervous for something?

I hope that I answered your question.
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