gastric motility Flashcards
What kind of accommodation does the stomach exhibit when food enters?
receptive relaxation due to the swallowing refulx and response to gastric mechanorecrpots
What NT are released during receptive relaxation?
ACH-VIP/NO, maybe something else?
What effect does the dorsal vagal complex have in response have during a meal?
a minor one
What is the Gastrocolic reflex
induces the need to defecate after ingesting a meal
What is the Gastroileal reflex
causes ileoceccal valve to relax transfer contents from small to large bowel
What is the optimal pH for gastric lipase? What does it do?
pH 3-6, produces free fatty acids
Is there active transport in the stomach?
no, only absorbed by diffusion-alcohol and aspirin
The emptying of liquids in the stomach uses?
the proximal stomach using tonic contractions and the pyloris opens partially in response to feedback from the duodenum
the empyting of solids in the stomach uses?
antral stomach pump uses phasic contractions driven by basal electrical rhythm to grind the meal
How big must the food be to passs through the pyrolus?
<2mm
What does the peristalsis occur at?
basic electrical rhythm- 3-5 min
How can amplitude of the BER be changed?
neural (aCH causes Ca influx) and hormonal (gastrin)
What determines the magnitude of contraction in the stomach?
number of AP on the crests of the slow waves determines the magnitude of contraction
What happens to the contractions are they get closer to the pyloric sphincter?
they speed up and strengthen
Does sugar or a solid meal empty the stomach faster>
sugar!
What inhibits gastric contractions adn emptying>
acid in the duodenum(enteric/vagal or hormonal secretin ad somatostatin), fat in the duodenum via CCK, osmolality of duodenal contents via enteric neural mechanisms (maybe hormones)
What does konjac flour do?
delays gastric empyting, keeps you fuller longer
What are the feedback mechanisms from the SI to the stomach?
nutrients- postive feedback to the fundus to relax, pylorus to contract, neg feedback to the antrum which grinds the food
When does the MMC work?
during fasting
What is phase 1 of the MMC>
Phase I: Quiescence
20-60 minutes
What is phase 2 of the MMC>
Phase II: Irregular,
Peristaltic Contractions
10-30 minutes
Increase in gastric, pancreatic juices
What is phase 3 of the MMC
Phase III: FASTING! Intense Contractions 5-10 minutes Pylorus opens fully Stimulated by some prokinetic drugs Benzoar hairball?
What is pyloric stensos
congenital condition where pylorus fails to relax after a meal leading to malnutrition and dehydration. Treated with surgical myotomy.
What is Gastroparesis? what is it due to?
delayed gastric empyting due to DM neuropathy (and surgery,drugs, cancer), the vagus and enteric nerves fail to generate enough force to empty the stomach
what do you treat Gastroparesis with?
prokinetic drugs- cisapirzide or metocloproamie
what is Dumping Syndrome
rapid gastric emptying usually due to gastric by pass, high sugar meals.
How does the body deal with dumping syndrome?
water moves into the lumen resulting in hypovolemia and reduced blood pressure. Results in nausea, weakness, dizziness, sweating, shakiness, diarrhea, heart palpitations
how does Peptic ulcer disease lead to abnormal motility
scarring and ulcers near the pylorus can delay emptying or in duodenal ulcers can lead to rapid gastric emptying due to loss of duodenal negative
feedback mechanisms.
What are some causes of vomiting
gastritis, poisoning, brain tumors, increased intracranial pressure, migraine, vestibular problems, bowel obstruction
What is regurgitation?
the return of undigested food (that has not yet reached the stomach) back up the esophagus to the mouth.
What are sensors for vommiting?
phaynx, higher centers, vestibular info, irritants of blockage of GI tract, blood born elements
What does the parasympathetics due in response to vommiting?
increase salivation (bicarb) to protect teeth
Where does retro-peristalsis start?
middle of small intestine
What can happen before vomiting>
retching- inspiration against a closed glottis
What is the mecahnism of vomiting?
glottis closes, hyoid moves up and forward opening the UES, diaphragm and ab muscle contracts moving food into esophagus as LES relaxes
Does the stomach contract during vomiting?
NO, just the annular notch
Does the esophagus retroperistalsis during vomiting>
no, all control is mediated by extrinsic nerves
What are NT that are inhibited to control vomiting?
dopa, histamine, and serotonin
