gastric secretions Flashcards
which cells secrete HCl
parietal cells
how are parietal cells stimulated (what receptor, what neurotransmitter)
Ach M3 receptor (think parasympathetic)
what do parietal cells secrete other than HCl
intrinsic factor
what is gastrin
released from G cellsbinds to cholecystokinin receptors on parietal cells, activates H+ ATPase pump
what do chief cells release
pepsinogen
what is pepsinogen
zymogen of pepsin
how is pepsinogen activated
acidic environment
what stimulates pepsinogen release
vagus activation Ach release, NO, secretin, gastrin
what do ECL secrete, how are they stimiulated, what do they do
histamine, ach from vagus, histamine binds to H2 receptor on parietal cells -> HCl released into the lumen of the stomach
what is the top neck of the stomach called
cardia
what is the area where the gastric bubble is called
fundus
where are the majority of D and G cells
antrum
what is the bit just before the exit sphincter of the stomach called
pylorus
mechanisms of somatostatin inhibition (3)
block histamine action on parietal cells
binds to ECL to stop histamine release
binds to G cells to inhibit gastrin release
what triggers somatostatin release
low pH in anrtum
how do prostaglandins inhibit acid
bind to PG receptors on parietal cells
stimulate mucus cells so more muucs -> more HCO3
explain NSAID and aspirin damage
inhibit prostaglandin production -> less mucus via COX pathway -> lowered pH and thinner mucus
what is Zollinger Ellison syndrome?
gastrinoma -> ++gastrin-> ++HCl -> many ulcers
what is the role of paneth cells
mostly controlling the microbiota of teh intestine
where do you find paneth cells. what do they look like histologically
bottom of crypts of lieberkuhn
columnar with eosinophilic granules
describe S cells
in the small intestine crypts of lieberkuhn
secrete secretin into the bloodstream
what does secretin do
raise pH of chyme when it enters duodenum
inhibits gastrin
stimulates HCO3 release from pancreas by increasing activity of HCO3 Cl- exchanger
