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What are the 2 divisions of the Enteric Nervous System
Myenteric (Auerbach's)
smooth muscle
- Submucosal (Meissner's)
- secretion and absorption
- local blood flow
- neuroimmune
- prominent in small intestine
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Paraympathetic Innervation of the Enteric Nervous System
vagus and pelvic nerves
large ratio of preganglionic to post ganglionic nerve fibers
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Sympathetic Innvervation of Enteric Nervous System
Collateral ganglia- Celiac, Superior mesenteric, Inferior mesenteric
induces relaxation generally
excitatory at some sphincters
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Functions of Enteric Nervous System
Control blood flow, in concert with CNS
CNS can redirect blood flow in times of need
- regulates glands within the GIT
- CN X: HCl, pepsinogen, pancreatic enzyme
- pancreatic islet cells: insulin, somatostatin, glucagon, pancreatic polypeptide
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Eccrine glands
on body surfaces, more on palms/soles
secrete water and electrolytes
dual innervation- muscarinic and adrenergic
sweat more when you are nervous
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Apocrine Glands
located on axilla, breast, eyelids, anogenital area
secretes mucoid substance
primarily adrenergic receptors
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GABA
inhibitory in CNS
Benzodiazapines- GABA agonists
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Nitric Oxide
stimulated by: Ach, norepi, bradykinins, thrombin, ATP, vasopressins
vasodilation
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Enkephalins
secreted by GIT and brain
bind to opioid receptors
preferentially bind to gamma receptors
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Endorphins
modulate pain
bind to u receptor
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Substance P
peristalsis
pain in peripheral nerves
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Alpha1 receptors
CONSTRICT
- dilator muscle=dilated eye
- blood vessels
- sphincters
- uterine muscles
- ejaculate
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Beta1 receptors
Heart = increase HR and contractility
Kidneys= production of renin
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Beta2
EXPANDS
increase cAMP
- =relaxes smooth muscle
- dilates bronchioles
- vasodilator
- relax bladder
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