stomach Flashcards
stomach compliance
no increase in pressure within the stomach therefore the stomach contents remains in the stomach
H+ and pepsinogen secretion is increased by __________ and inhibited by ____________
H+ and pepsinogen secretion is increased by gastrin and inhibited by somatostatin
pH of the stomach is low and this stimulates D cells to secrete somatostatin that in turn inhibits gastrin release from GI cells
interdigestive phase
mediated through the vagus nerve/submucosal plexus and is a positive regulator for all stomach functions
cephalic phase
mediated by food entering the stomach. this causes firing of the stretch receptors, increase pH and the release of gastrin. Mucin, pepsinogen, H+ and gastrin release is timulated. Gastrin release is increased due to increased pH and digestive products being produced. gastrin also causes an increase of stomach mixing
gastric phase
mediated by digestive products and H+ moving into the small intestine. These materials cause the release of CCK, GIP and secretin that inhibit H+, pepsinogen and stomach mixing and slow releasing of material from the stomach into the small intestine
intenstinal phase
passage time through the esophagus
10 s
begins protein digestions
pepsin
______ strongly increases vascular permeability
histamine
D cells release
somatostatin
inhibits gastrin release
somatostatin
G cells release
gastrin
stimulates acid secretion and pepsinogen secretion
gastrin
cell source of gastrin releasing peptide
vagal nerve endings
target of gastrin
parietal cell in the stomach
target of gastrin releasing peptide
antrum of stomach
target of somatostatin
stomach
release H+ and intrinsic factor
parietal cells
release pepsinogen which is cleaved to the active protease pepsin
chief cells
gastrin stimulates ____ and ____ to secrete more pepsinogen, H+ and intrinsic factor
chief and parietal cells
cephalic phase positive regulators
- food
- vagus nerve
- chief cells, mucous cells, parietal cells and G cells
Gastric phase regulators
- stretch receptors leads to distension of stomach
- acid release
- gastrin relase
pepsinogen is secreted by the
chief cells
the bulk of protein digestion does not occur in the stomach but in the small intestine
yep
how does low pH affect gastrin release?
low pH stimulates D cells to secrete somatostatin which inhibits gastrin release
inhibition of gastrin release leads to
decrease in parietal cell, chief cell and ECL cell release
Most H+/K+ ATPase are sequestered within ______ in the parietal cell cytoplasm until there is a rise in pH and they fuse with cell membranes to pump out hydrogen ions
tubulovesicles
med that buffers stomach acid
antacids
med that blocks histamine binding to parietal cells
H2 receptor blockers
drug forms covalent bond to proton pump and inactivates its function
proton pump inhibitors
majority of chyme entering the small intestine is
< 1mm
the functional purpose of the inhibitory gastric secretion by intestinal factors is the slow passage of chyme from the stomach when the small intestine is already filled or already overactive
yep
