GI mod 2 Flashcards
what is digestion
secretion of gastric juices
digests food into chyme
what is chyme
partially digested food
absorption in stomach?
none, except aspirin, NSAIDS, alcohol
how much alcohol absorbed in stomach vs SI
20% stomach
80% SI
carbonated drink and empty stomach - absorption rate
absorbs faster
stomach and motility
after initial digestive processes the stomach propels food into duodenum
what stimulates relaxation of stomach to prepare for bolus
swallowing
relaxation of the stomach musculature allows what?
allows the stomach to serve as a reservoir for the incoming food
stomach has ability to accommodate large volume changes?
true
what is the vago-vagal reflex
food enters stomach - stomach distension stimulates vagal mechanoreceptors which reflexively stimulate vagal VIP (vasointestinal peptide) release to relax smooth muscle of stomach wall
what is the stimulus of gastric emptying
parasympathetic activity
sequence of gastric emptying
- retropulsion: contractions push food back towards the body of the stomach - 4-5 sequential peristaltic waves push chyme back and forth (churn)
- the last wave forces pyloric sphincter to open and allow small amount of chyme is pushed into duodenum
how open does the pylorus get?
just a small amount 1-2cm
-not enough to have duodenum regurg back into pylorus
another name for pylorus
antrum
what passes faster liquids or solids
liquids
why type of solids pass faster than others?
carbs and proteins empty faster than fats
how long does it take to empty 50% of stomach
2-3hrs
total emptying time of stomach?
4-5hrs
rate of gastric emptying is dependent on what
volume . osmotic pressure and type of food ingesteed
factors that increase rate of gastric emptying
larger food volume increases rate of gastric emptying
factors that decrease rate of gastric emptying
- hyper/hypotonic fluid
- fatty foods
- increased rate of acids entering duodenum
* *these act as a negative feedback loop from the duodenum
how does hyper/hypotonic fluid decrease rate of gastric emptying
receptor in stomach/duodenum detect osmotic pressure
–this allows time to create/facilitate an isoosmotic environment for duodenum
how does fatty foods decrease rate of gastric emptying
- -CCK (cholecsystokinin) synthesized and released by duodenum/SI will inhibit gastric motility and decrease acid production
- -fats are digested in the duodenum - if too much fat enters SI then feedback loop slows down rate to allow time to properly digest fats
how does increased rate of acids entering the duodenum decrease the rate of gastric emptying
acid is neutralized in duodenum so if too much entereing then feedback is to inhibit gasyric emptying to decrease acid entering duodenum