GI motility Flashcards
how many sphincters along the GI tract
7
increases the tone of the gut and the velocity and intensity of contractions.
exerts control primarily over digestive motility
myenteric plexus
involved with local conditions and controls local secretion, absorption, and muscle movements.
its principal role is in sensing the environment within the lumen
submucosal plexus
mass movements are long, slow powerful contractions that move over the colon 3 or 4 times per day, typically
after meals
buccal phase voluntary/involuntary
voluntary
pharyngeal phase voluntary/involuntary
involuntary
esophageal phase voluntary/involuntary
involuntary
sympathetic division acts through sympathetic nerves to
inhibit enteric nervous system
parasympathetic division acts primarily through the dorsal motor nucleus of the vagus nerve to
stimulate ENS activity
excitatory, stimulates smooth muscle contraction, increases intestinal secretions, release of enteric hormones and dilation of blood vessels
acetylcholine
derived from extrinsic sympathetic neurons and is almost always inhibitory and has the opposite effect of acetylcholine
norepinephrine
GI smooth muscle are linked electrically linked by
gap junctions
pacemaker cells that have the capacity to generate the basic electrical rhythm or slow wave activity
interstitial cells of cajal (ICCs)
upper esophageal sphincter is composed of _______ muscle
striated and circular
lower esophageal sphincter is composed of ______ muscle
smooth and longitudinal
occurs when stomach acid flows back into the esophagous
GERD
precancerous condition that develops as a results of GERD
Barrett’s esophagus
motor disorder characterized by a complete loss of contraction and relaxation of muscles used to move contents down the esophagus
esophageal achalasia
condition where the stomach protrudes through the diaphgram into the chest alongside the esophagus
paraesophageal hernia
is a pouch that protrudes outward in a weak portion of the esophageal lining
esophageal diverticulum
smooth muscle is continuous throughout the GI tract
yep
action of Ach to sphincter
contractions
action of NO and VIP-vasoactive intestinal polypeptide
relaxation
GI tract peristalsis is defined by
NO relaxing the muscle first in front of the bolus and Ach contraction of the muscle behind the bolus second
positive regulators of eesophageal smooth muscle
- Ach
2. substance P
negative regulators of eesophageal smooth muscle
- NO
2. VIP
pressure between the ilieal and colon with the ileocecal sphincter
- decrease in pressure with ileal distension
2. increase in pressure with colonic distension
fluid content of stool as it moves through the colon
decreases
slow contractions that occur about every 30 minutes and last approx. 1 minute. they are stimulated by stretch when food remnants fill the haustra
haustral contractions
primary movements seen in the large intestine include (2)
haustral contractions and mass movements
are long slow moving, powerful contractions that move over the colon 3 or 4 times per day typically after meals
mass movements
what initiates the defacation reflex
stretch receptors