L3- Stomach secretions Flashcards
functions of the stomach
- store food
- regulates the release the contents into the duodenum
- mix the food with the gastric secretions
what is the inner lining called in stomach and in other organs
mucosa
function of mucous neck cell
- mucous neck cell- produces mucous and bicarbonate fluid to protect from injury and acid erosion
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function of parietal cell
secretes acid and intrinsic factor ( for absorbing food)
-predominantly found in the corupus region
function of chief cell
secretes pepsinogen whhich is a precursor for pepsin
- predominantly found in the corupus region
function of ECL like cells
secretes histamine to trigger acid secretion
- in corpus region
function of d cells
secretes somatostatin for acid secretion
-found in corupus, antrum and pylorus region of the stomach
function of G cells
secretes gastrin for acid secretion
- found in antrum and pylorus region of the stomach
what happens when a parietal cell is stimulated
- CO2 diffuses into the cell
- joins with water to make carbonic acid caytalsed by carbonic anhydrase
- the acid dissociates into H+ ion and HCO3-
- HCO3 transported out into the blood in exchange of CL- ions, resulting in alkaline tide in the plasma
- H ions transported out into the lumen in exchange for K+ ions through ATPase.
- now the acid is produced in the lumen
how does gastrin regulates acid secretion
- gastrin - stored in vesicles along the basolateral membrane of the cell and gets released through vagal stimulation
- increases expression of protom pumps in the parietal cells in the antrum
- gastrin binds to ecl cell to stimulate histamine synthesis and the histaine act upon the H2 receptors on pareital cells to release acid
what part of the nervous systems control the functions of the stomach
- ENS through vagus and sympathetic nerves
how can ACH act upon acid secretion
- stimulates parietal cells to release acid and G cells to release gastrin
- stimulates ECL cells to release histamine
- stimulates D cells to inhibit somatostatin release
– ACH stimulates G cells which then stimulates parietal cell directly and indirectly via ECL cell
triggers for acid secretion
gastrin, histamine, ACH,
inhibitory factors for acid secretion
- somatostatin
- CCK
- secretin
- VIP and GIP
how does secretin act upon the acid secretion inhibition
- inhibits gastrin release and acid secretion
- stimulated by the acid in the duodenum