brief description of enteric nervous system

1. By
Dr. Indusree. C. Suseelan
3rd yr PG
Dept. of Shareera Rachana,
Sri Dharmastala Manjunatheswara college of Ayurveda,
udupi 12017 dr indusree c suseelan

2. 2
Peripheral nervous system by J.N Langley
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4. Enteric nervous system
• Confined within the wall of the GUT
• Extends from oral part of the Esophagus to
the Internal anal sphincter.
• 2 sets of intercommunicating nerve plexus
– MYENTERIC / AUERBACH plexus
– SUBMUCOUS / MESSINER plexus
Both plexus are composed of intricate
network of fine un-myelinated nerve fibers
intermingled with clusters of neuronal cell
bodies arranged in the form of ganglia
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5. MYENTERIC PLEXUS
• AUERBACH’s plexus
• Located b/w the outer longitudinal and the inner
circular layers of smooth muscles extend from the
upper esophagus to the anus.
• Multipolar
• Motor function
• Controls mainly the gastrointestinal movements
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6. SUBMUCOSAL PLEXUS
• MEISSNER’s plexus
• Lies b/w the inner circular smooth muscle and the
muscularis mucosae and runs from the stomach to the
anus.
• Bipolar/ unipolar  Sensory function
• Multipolar  interneurons.
• Controls mainly gastrointestinal secretions & local blood
flow
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8. Secretory
functions
Can even function
Without the
participation of ANS
**
Peristaltic
movements
ENS works independently to
maintain
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9. Equivalent to
total no: of
neurons in
spinal cord
Derived
from
specific
area of
neural crest
cells
10-100
million
neurons
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10. Supported
by astrocyte
like glial
cells
BLOOD –
GANGLION
BARRIER
No
endoneurium
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11. Sensory
neurons
Motor
neurons
interneurons
3 types of functional neurons:-
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12. Sensory neurons
• Bipolar / unipolar neurons
• Confined in the Sub-mucous plexus
• Activated by- distension of gut wall- stretch receptors
• Receive chemical stimulation from mucosa- chemical
receptors
• Axons synapses with interneurons located close to the
circular muscle layer.
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14. interneurons
• Their axons are projected longitudinally
up & down to a series of motor neurons
which are located mostly in the
myenteric plexus & some in submucosal
plexus
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15. Motor neurons
EXCITATORY
*Acetylcholine
(Ach)
*Substance-P (SP)
INHIBITORY
*adenosine triposphate
(ATP)
*vasoactive intestinal
polypeptide(VIP)
*Nitric oxide (NO)
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17. Motor neurons project fibers
o Smooth muscle fibers of outer longitudinal and inner circular
layers,
o muscularis mucosae,
o glands &
o blood vessels of the gut.
Some fibers projected outside the gut
o to the ANS for modulation of the neural output &
o to the mesenteric blood vessels for regulation of the blood
flow.
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Gastro-intestinal reflex pathway
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20. MYENTERIC PLEXUS
• Controlling muscle activity
along the length of the gut with
specific effects:-
– Increased muscle tone
– Increased intensity of the
rhythmical contractions
– Slightly increased rate of the
rhythm of contraction
– Increased velocity of
conduction of excitatory
waves along gut wall, causing
more rapid movement of gut
peristaltic waves
• Composed of excitatory as
well as inhibitory neurons
SUB-MUCOSAL PLEXUS
• Controlling function within the
inner wall of each minute segment
of intestine such as:-
– Local intestinal secretion
– Local absorption
– Local contraction of sub-
mucosal muscle
That causes various degrees of in-
folding of G I mucosa.
• Composed of mainly excitatory
neurons
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21. Applied anatomy:-
• Injury to the ENS neurons or its pathway
may leaded to chances of slow recovery
due to absence of endoneurium
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