GI Tract II

Question 1

enteric motor neurons: do what? shape?

Answer 1

conduct impulse to effector tissues. dogiel type I.

Question 2

enteric motor neurons: electrical activity?

Answer 2

simple pattern. easily excitable

Question 3

inhibitory motor neurons: project which direction? role? mediators (4)?

Answer 3

project anally, relax smooth muscle. NO, ATP, PACAP, VIP

Question 4

excitatory motor neurons: project which direction? role? mediators (3)?

Answer 4

project orally, contract smooth muscle. ACh, 5HT, tachnkinins like SP

Question 5

excitatory/inhibitory motor neurons realy signals to ____ through the ____?

Answer 5

signals to smooth muscle cells, through the ICC

Question 6

secretomotor neurons: roles? present where?

Answer 6

stimulate intestinal secretion, can also induce vasodilation of mucosal blood vessels. mainly present in sub-mucosal plexus

Question 7

paralytic ileus: aka? what? caused by?

Answer 7

reflex activation of post synaptic sympathetic neurons can result in total shut down of intestinal motility and secretion, aka the entero-enteric reflex.

Question 8

enteroenteric reflex: occurs in what ganglia

Answer 8

inferior mesenteric ganglia, aka the extra CNS site of reflex activity

Question 9

prevertebral sympathetic ganglia: input from 2 sources?

Answer 9

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.

Question 10

what transmitters for mesenteric enteric neurons (5)

Answer 10

nic. ACh, CCK, VIP, CGRP

Question 11

what transmitters for sensory dorsal root ganglia? (2)

Answer 11

substance P, CGRP

Question 12

in the IMG: substance P mediates what?

Answer 12

late slow EPSP

Question 13

input to ganglia is generated by? output is?

Answer 13

input: colonic distension. output: noradrenergic, inhibitory projection to gut ganglia

Question 14

defectation under what control?

Answer 14

internal + external anal sphincters, but only external under voluntary control

Question 15

fright induced defectaion caused by?

Answer 15

symapthetic stimulation of the longitudinal muscle of rectum

Question 16

interstitial cells of cajal: origin? characterized by?

Answer 16

smooth muscle origin. characterized by presence of a growth factor receptor c-kit that triggers their differentiation

Question 17

interstitial cells of cajal: what/where? generate what? which leads to?

Answer 17

networks in myenteric plexus that generate spontaneous slow waves of depolarization: lead to paced contractions of smooth muscle of non-neuronal origin

Question 18

ICC: networks in deep muscular plexus important for?

Answer 18

important to relay nerve impulses to smooth muscle cells

Question 19

knockout/prevention of ICC development ?

Answer 19

seriously affects spontaneous pacing activity and response to nerve activity

Question 20

summary: excitatory NTs vs. inhibitory NTs in peristaltic reflex?

Answer 20

inhibitory/relaxation = NO, PACAP, VIP, ATP. excitatory/contraction = ACh, Sub P, 5 HT