Lecture 37 - Gastric Motility & Vomiting Flashcards
what inhibits gastric acid secretion
- stimuli that promote acid secretion are no longer active
- low intragastric pH, D cells secrete somatostatin inhibiting release
Fundus
receives and stores ingesta and adapts to increases in volume
Gastric body
mixes saliva and gastric juice with food
Antrum
regulates the propulsion of food past the pyloric sphincter into the duodenum
Pylorus
allows small amounts of finely ground liquid chyme to pass
what are the 4 functions of the stomach
- storage
- grinding of food
- controlled delivery rate to duodenum
- acid secretion and regulation
Gastrin ____ acid secretion while somatostatin ____ it
increase; decrease
T/F: gastric distension activates the vagus nerve directly
TRUE
describe the motility of the proximal stomach
tonic contractions (weak)
storage of food
describe the motility of the distal stomach
slow wave, intense peristalsis
propel, grind, and mix
what 2 substances inhibit gastric motility
- secretin
- cholecystokinin
describe the migrating motor complex
distinct pattern of electromechanical activity in GI smooth muscle during fasting regulated by motilin
“housekeeper” = non-selective, larger particles
what are the components of the afferent limb for the vomiting apparatus
- chemoreceptor trigger zone (4th ventricle)
- Vestibular apparatus
- Abdominal viscera
- Cerebral Cortex
T/F: H1-histaminergic receptors in the CRTZ and vestibular apparatus are more important in cats than dogs
FALSE
T/F: ruminants undergo internal vomiting by ejecting abomasal contents into the rumen
TRUE
T/F: horse vomiting is rare
TRUE
describe vomiting clinical signs in 5 steps
- nausea, hypersalivation
- reverse peristalsis
- inspiration against closed glottis (- intrathoracic pressure)
- abdominal contraction (+ abdominal pressure)
- gag
what are the 3 ways we can make animals vomit? what do they stimulate?
- hydrogen peroxide - pharynx and stomach
- dopamine receptor agonists (apomorphine/ropinirole) - CTZ
- alpha 2 agonists - CTZ in cats
give the receptors and species the listed emetic effects:
xylazine/dexmedetomidine
a2 agonist
cat
give the receptors and species the listed emetic effects:
apomorphine
dopamine agonist
dog
give the receptors and species the listed emetic effects:
ropinirole
dopamine agonist
dog
give the receptors and species the listed emetic effects:
hydrogen peroxide
irritation/inflammation
dog
what substances are responsible for stimulating abdominal viscera in dogs and cats
serotonin
what anti-emetic blocks serotonin? what receptor is blocked?
ondansetron; 5HT
what substances are responsible for stimulating CTZ in dogs and cats
dogs = dopamine, norepinephrine
cats = norepinephrine
what anti-emetic blocks dopamine? what receptor is blocked?
metoclopramide; D2
what anti-emetic blocks norepinephrine? what receptor is blocked?
chlorpromazine; a2
what substances are responsible for stimulating the vestibular apparatus in dogs and cats
dogs = histamine
cats = acetylcholine
what anti-emetic blocks histamine? what receptor is blocked?
diphenhydramine; H1
what substances are responsible for stimulating the vomiting center directly in dogs and cats
dogs = substance P, norepinephrine
cats = serotonin, substance P, norepinephrine
what anti-emetic blocks substance P? what receptor is blocked?
maropitant; NK1
what are the 4 metabolic consequences of vomiting
- loss of HCl (alkalosis)
- loss of HCO3 (acidosis)
- loss of K+ (hypokalemia)
- loss of H2O (dehydration, hypovolemia)
duodenal V+
simple stomach animals, reverse peristalsis
gastric V+
pyloric outflow obstruction in ruminants and humans
