Ingestion/Motility Flashcards
name the general functions of the GI tract
- ingestion/motility
- digestion/secretion
- absorption
- regulation of GI function
movement of food throughout the system is controlled by the ____
intrinsic enteric nervous system
within the tract, there are pacemaker cells known as ____
interstitial cells of Cajal
AP of interstitial cells of Cajal is the same as the…
SA/AV node of the heart
slow waves in an AP are known as…
drifting resting membrane potential
action potential in the intrinsic enteric nervous system is called ____
spike potential
what occurs during the rising phase?
Ca in
what occurs during the falling phase?
K out
what effect does the number of spike potentials have on contraction?
larger number of spike potentials -> stronger contraction
what increases peristalsis?
parasympathetic (Ach)
what decreases peristalsis?
sympathetic (NE/E)
activation of the ____ is associated with contraction of smooth muscle in the GI tract
Myenteric plexus (Auerbach’s Plexus)
the extrinsic nervous system innervates the ____
Myenteric Plexus (Auerbach’s Plexus)
name the 4 types of contraction by the Auerbach’s plexus
- tonic contractions
- giant migrating complexes
- migratory motor complexes (MMCs)
- mixing contractions
there is always ____ due to the parasympathetic nervous system always being on at 50%
tone
what increases tone?
parasympathetic (Ach)
what are the parasympathetic innervations that affect tone?
- vagus (CN X) from esophagus to splenic flexure of LI
- S2, S3, S4: descending colon to anus
what is responsible for decreased tone?
sympathetic (NE/E)
giant migrating complexes (mass movements) are increased by ____
serotonin
what is the function of giant migrating complexes?
allows contractions over long distances as required for bowel movement
migratory motor complexes are increased by ____
motilin
function of migratory motor complexes
housekeeping function: keeps moving contents toward the colon
where do mixing contractions primarily occur?
stomach
name 3 examples of reflexes
- gastrocolic (stomach -> colon)
- enterogastric
- colonoileal
if gastrocolic reflexes are going “forward,” what happens to the rate of contractions?
increases
if gastrocolic reflexes are going “backward,” what happens to the rate of contractions?
slows
