GI Tract II Flashcards
enteric motor neurons: do what? shape?
conduct impulse to effector tissues. dogiel type I.
enteric motor neurons: electrical activity?
simple pattern. easily excitable
inhibitory motor neurons: project which direction? role? mediators (4)?
project anally, relax smooth muscle. NO, ATP, PACAP, VIP
excitatory motor neurons: project which direction? role? mediators (3)?
project orally, contract smooth muscle. ACh, 5HT, tachnkinins like SP
excitatory/inhibitory motor neurons realy signals to ____ through the ____?
signals to smooth muscle cells, through the ICC
secretomotor neurons: roles? present where?
stimulate intestinal secretion, can also induce vasodilation of mucosal blood vessels. mainly present in sub-mucosal plexus
paralytic ileus: aka? what? caused by?
reflex activation of post synaptic sympathetic neurons can result in total shut down of intestinal motility and secretion, aka the entero-enteric reflex.
enteroenteric reflex: occurs in what ganglia
inferior mesenteric ganglia, aka the extra CNS site of reflex activity
prevertebral sympathetic ganglia: input from 2 sources?
axons of neurons that have cell bodies in gut wall, aka mesenteric enteric neurons. sensory axons of nerves that have cell bodies in sensory/dorsal root ganglia.
what transmitters for mesenteric enteric neurons (5)
nic. ACh, CCK, VIP, CGRP
what transmitters for sensory dorsal root ganglia? (2)
substance P, CGRP
in the IMG: substance P mediates what?
late slow EPSP
input to ganglia is generated by? output is?
input: colonic distension. output: noradrenergic, inhibitory projection to gut ganglia
defectation under what control?
internal + external anal sphincters, but only external under voluntary control
fright induced defectaion caused by?
symapthetic stimulation of the longitudinal muscle of rectum
interstitial cells of cajal: origin? characterized by?
smooth muscle origin. characterized by presence of a growth factor receptor c-kit that triggers their differentiation
interstitial cells of cajal: what/where? generate what? which leads to?
networks in myenteric plexus that generate spontaneous slow waves of depolarization: lead to paced contractions of smooth muscle of non-neuronal origin
ICC: networks in deep muscular plexus important for?
important to relay nerve impulses to smooth muscle cells
knockout/prevention of ICC development ?
seriously affects spontaneous pacing activity and response to nerve activity
summary: excitatory NTs vs. inhibitory NTs in peristaltic reflex?
inhibitory/relaxation = NO, PACAP, VIP, ATP. excitatory/contraction = ACh, Sub P, 5 HT
