L6- gastric motility Flashcards
an adaptation of the stomach to accommodate the food
- highly folded so it flattens out once the food is filled in and the intraluminal pressure increases
- the pressure increase rapidly if it’s filled near its max limit due to an interruption of vago-vagal reflex
- the reflex regulates the relaxation of the stomach
3 phases of gastric motility
- propulsion
- grinding
- retropulsion
what happens in propulsion
- liquids and smaller particles go into the pylorus
what happens in grinding
- larger particles are retained in the antrum, causing a bulge in the stomach
- so they can be broken down into smaller pieces
what happens in retropulsion
-those broken down particles go into pylorus into the duodenum
functions of pylorus
- regulates emptying of gastric contents into the duodenum
- prevents duodenul contents back into the stomach
3 phases of gastric emptying
-cephalic
-gastric
intestinal
what happens in celphalic phase
approach of food in the mouth or the stomach
- vagus nerve inhibited so the stomach relaxes to a larger vol to accomodate the food
- inhibitory phase
what happens in gastric phase
- excitatory phase
- stomach empties at a rate equal to the vol of it
- SM contraction causes relfex contraction of the stomach
- activation of pressure receptors inthe nerves
- gastrin released
what happens in the intestinal phase
- inhibitory phase where the duodenum adapts to the contents filling
- ileogastric reflex - pressure receptors in the ileum due to food filling so it can delay gastric emptying fro digestion
what molecules are released in response to
- low pH
- high fats
- high AAs
- high carbohydrates
pH - secretion activated and released
fats - CCK secretion increased
AAs- gastrin secretion increased
carbohydrates - GIP secretion increased
functions of GIT so small and large intestine together
- produces segmental contractions, not propulsive and mixes the food together
- produces peristaltic contractions for propulsion, so the food can move in one direction
- acts as storage for contents
location of small intestine
- extends from stomach to colon
- responsible for digestion and absorption
functions of small intestine
-mixing, propulsion and release of chyme into colon
types of motility in the small intestine in the fed state
- segmentation
- peristalsis
what is segmentation
-rings of circular muscle at the intervals which contract or relax for mixing food
what is peristalsis
muscle of the GIT contracting and relaxing to propels the food froward
what complex or mechanism is involved in fasted state
migrating motor complex (MMC)
what is MMC
- rhymatic contractions
- makes sure that the gut is clean by moving the food along due to the contraction of the muscles
- the activity of the MMC is its highest at the start of jejujum and then decreases as you go along the jejujum
benefits of MMC
- prevents bacterial overgrowth and stops the batceria from going into the small bowel
- removes undigested contents in the guts
2 reflexes in ileum and the functions of them
- ileogastric reflex - decreases gastric motility
- gastroileol reflex - increased gastric activity increases ileal motility and movement of chyme
- mediated by ENS
what’s ileocaecal sphincter
- seperate ileum from colon
- controls the flow of ileal contents into the colon
- mediated by ANS and ENS and regulated by luminal contents and pressure
colon features
has no villi and low SA
- has longitudal muscle
- split up into ascending, transverse, descending and sigmoid
function of colon
- gut microbiota, environment for beneficial bacteria to synthesise bacteria
- absorb fluid and electrolytes, FAs
- storage
- regulates release of faecal material
- secretes mucus and ions
