Gastrointestinal Physiology
Enteric nervous system
lies in the wall of the gut (esophagus anus)
controls GI movement and secretions
consists of 2 plexuses
o myenteric - peristalsis
o submucosal secretion and (local) blood flow
axon endings secrete acetylcholine which excites gastrointestinal activity, and norepinephrine, which inhibits it
Parasympathetic innervation
cranial
o mouth & pharynx
o VAGUS nerve
esophagus, stomach, pancreas and (somewhat) the intestines through the first half of the colon
sacral
o via the pelvic nerves, innervate the lower half of the intestines
postganglionic neurons in the plexuses cause activity of the enteric nervous system
Sympathetic innervation
originate between T-5 and L-2
(most) preganglionic spinal neurons join the sympathetic chains and travel through peripheral ganglia, where their signals are dispersed to numerous neurons that spread throughout the gut
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