Shruti_ppt_physiilogy.pdf enteric nervous system

Physiology
Enteric nervous system

1. Metasypathetic nervous system
(enteric nervous system)
By -shruti sawdatkar

2. The enteric nervous system (ENS) controls the
digestive system, connecting through the central
nervous system (CNS) and sympathetic nervous
system. It has a web of sensory neurons, motor
neurons, and interneurons embedded in the wall
of the gastrointesinal system, stretching from
the lower third of the esophagus right through to
the rectum. The neurons of the ENS are arranged
in two layers, the submucosal and myenteric
plexuses of the gut wall. Image 1:The ENS is
embedded in the lining of the gastrointestinal
system.
Introduction

3. It has been estimated that the ENS actually contains more neurons than the
whole of the spinal cord.
The ENS processes a range of sensations, such as the nature of gut contents
and gut distension, and integrates this information with input from the
autonomic nervous system. In this way the ENS can guide and optimise the
muscular and secretory activity of the gastrointestinal tract.
Many of the ENS effector neurons are also innervated by parasympathetic
motor neurons, so they act as effector neurons of the parasympathetic nervous
system. For this reason the ENS is regarded as an integral part of the
parasympathetic nervous system, but its specialized sensory neurons and
independent processing make it rather more complex than a simple
parasympathetic ganglion.
The ENS displays sophisticated coordination and exhibits plasticity and
learning in response to changing dietary habits or disruptions to the gut[1].

4. Structure and Function
The enteric nervous system contains between 200 and 600
million neurons and 20 different types of neurons. With
such complexity, the enteric nervous system is sometimes
referred as the "second brain" or "the brain in the gut".
Its neurons are grouped in thousands of ganglia which are
either:
Myenteric: organised in a network around the gut, which
spans the length between the upper oesophagus and the
internal anal sphincter and contains mostly motor neurons.
Submucosal: localised in the small and large intestine with
most of the primary afferent sensory neurons. ie conveying
information to the brain..
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Structure and function

5. Functional anatomy of gut-brain
communication and the enteric nervous
system (ENS).
Panel A is a simplified scheme to demonstrate
control of gut functions at different levels. The
most relevant is the ENS, which controls gut
functions independent of extrinsic inputs.
Nevertheless, the gut is connected to the brain
via nerves which function as the gut-brain axis
–
sensory neurons with cell bodies in dorsal root
ganglia or in parasympathetic relay ganglia, e.
g. nodose ganglion, and efferent nerves of
the parasympathetic and sympathetic nervous
systems.

6. Top: the general organization of the enteric nervous sys tem. The myenteric plexus lies
between the longitudinal and circular muscle layers. The submucosal plexus lies in the
submucosa and in larger animals (not shown) consists of an outer and an inner compo nent.
Nerve fibers connect the ganglia and form nerve plexuses that innervate the longitudinal
muscle, circular muscle, muscularis mu cosa, and mucosa. There are also enteric nerves
innervating arteries in the submucosa, as well as the gut-associated lymphoid tissues. The
mucosa is densely innervated. Enteric glia are found associated
with enteric nerves throughout the wall of the gut

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Mammalia organisms form intimate interfaces with commensal and pathogenic gut
microorganisms. Increasing evidence suggests a close interaction between gut
microorganisms and the enteric nervous system (ENS), as the first interface to the
central nervous system. Accumulating evidence suggests that the development and
homeostasis of the ENS are mediated by luminal (the inner open space of the gut)
microbial factors. In particular, pathogens may take advantage of ENS
neurotransmitters to potentiate their action or even create an intestinal
microenvironment suitable for their reproduction. In addition, the ENS may
represent the first interface between the intestinal content and the CNS, thus
explaining the intricate relationships behind intestinal microbes and their effects on
CNS inflammation, behavior, and even actions

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The enteric nervous system is capable of working independently of the central nervous system. The intestine is
the only organ in the body that can function autonomously.
When it needs to communicate with the brain it communicates through the vagus nerve and the Gut Brain Axis
Like the nervous system itself, the enteric nervous system synthesizes serotonin, dopamine, opioids for pain,
etc.
It monitors acidity, promotes bowel movement, and monitors our defense levels.
There’s evidence that it’s able to detect if there are any bacteria in the food we’ve eaten. If so, it will induce
processes such as vomiting or diarrhea.
Enteric neurons can regulate the vomiting reflex, which is particularly critical in those cases in which vomiting
arises as a side-effect of medical treatments, including chemotherapies
The basic functions of the
metasympathetic department of the ANS:
1. It participates in the maintenance of
homeostasis.
2. It carries out the role of the peripheral
nerve centers and provides constant and
continuous control over the work of the
internal organs.
3. It participates in the process of
information transfer from the sensory
receptors of the internal organs to the
CNS.

10. CONCLUSION
Enteric nervous system is a system with many regulatory features such as the intestinal flora, our and our
diet. They are in tight connection with neurot ransmitters while carrying out these functions.
Enteric nervous system is a neural structure that especially through the afferent and efferent fibers in the
vagus nerve, the neurotransmitters it releases and its connections with the autonomous nervous system.
As a consequence of these tight connections, any condition that affects our intestines can also show its
effect on the central nervous system. Likewise, a problem in our testines can reach our central nervous
system and affect our mood.
2
It is shown that the our enteric nervous system deserves more attention with its hundred million nerves
(which is the second highest number after the brain), its influences on our central nervous system and the
results that emerge with the help of our CNS

11. Thank You