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GIT 3 Innervation of GIT: Enteric Nervous System - Coggle Diagram
GIT 3
Innervation of GIT: Enteric Nervous System
2 major networks of nerve fibers
that innervate the GIT:
Intrinsic innervation
Myenteric plexus (Auerbach’s plexus).
It lies between longitudinal and
circular smooth muscle layers
and innervates both theses layers.
It is mainly motor in function.
Its stimulation
increases the activity of gut by:
increasing tone of gut wall
increasing intensity of rhythmic contraction
increasing rate of rhythmic contractions,
increasing velocity of conduction of
excitatory waves along the gut wall.
Thus, it is concerned with control of peristaltic activity of the GIT.
Submucous plexus (Meissner's plexus).
It lies between the submucous layer and inner circular smooth muscle layer.
It is mainly sensory in function
and is concerned with control of
exocrine and endocrine secretions
by the cells in the GIT.
It also innervate the submucosal blood vessels
to control local blood flow.
Both the plexuses are interconnected
and are under the extrinsic autonomic nerves control,
by both parasympathetic and
sympathetic nerve fibers
Extrinsic innervation
Parasympathetic (cholinergic) nerves,
release
acetylcholine (A-ch
) at
their endings
and by
depolarization
of smooth muscle membrane
produce
contraction
of GIT musculature.
Stimulation of parasympathetic nerves to GIT produces:
increase in motility and tone
relaxation of sphincters
increased secretions from the stomach (specially of enzymes) and of the intestine.
table
Sympathetic (adrenergic) nerves,
release
epinephrine
at their
endings
which by
hyperpolarization
of smooth muscle membrane result
in
relaxation
of GIT musculature.
Stimulation of sympathetic nerves to
GIT produces:
decrease in motility and tone
contraction of sphincters
inhibition of secretions from the stomach and probably also inhibit intestinal secretions.
table
together they form the Enteric nervous system
the Little Brain