Gastric Secretion Flashcards
At what part of the stomach does the main storage concentrate?
Fundus
What is the function of the body part of the stomach?
Storage Mucous HCL production Pepsinogen Intrinsic factor production
What part in the stomach is gastrin produced?
The pylorus antrum
How does the stomach prevent it digesting itself?
It binds pepsin to the inactive precursor pepsinogen
What is pepsin?
A proteolytic enzyme
What is gastrin produced from?
Specialised endocrine cells- G cells
What type of cells produce pepsinogens?
Cheif cells
What does parietal cells secrete?
HCL
intrinsic factor
What is the function of intrinsic factor and where is it produced?
Intrinsic factor is reauired for the absorption of vitamin B12
It is peoduced from parietal cells in the gastric glands
What enzyme converts co2 and water to H2CO3?
Carbonic anhydrase
In the cell, H2CO3 is beoken down into H and what ?
hCO3
When HCO3 leaves the cell, what enters the same time?
Chlorine (Cl)
what are the 3 different mechanisms of control of gastric secretion?
neurocrine - vase /reflexes
endocrine = gastrin
paracrine = histamine
what 3 phases are involved in inhibition of gastric secretion?
cephalic phase - stop chewing = decrease in vagus nerve
gastric = decrease in PH = decrease in gastrin
intestinal - acid in duodenum releases Secretin and activates enterogastric (splanchnic reflexes)
& fat in duodenum releases GIP
what are enterogastrones and name a few.
enterogastrones are hormones which inhibit gastrin production
i.e. prostaglandins, cholecystokinin CCK, GIP
where are enterogastrones released from?
gland cells in the duodenal mucosa
where is gastric mucous produced from?
epithelial cells and mucous neck cells
what is the main role of gastric mucous?
cytoprotective role and neutralises the PH
where is intrinsic factor secreted and where is it absorbed?
secreted from parietal cells
absorbed from ileum
what does stimulation of the vagus nerve do in terms of gastric production?
activates ACh which stimulates parietal cells
activates G cells which produces gastrin which activates parietal cells
what happens when gastrin/ACh stimulate ECL cells?
it causes histamine to be released from the ECL cells which stimulate parietal cells
how does fat in the duodenum inhibit gastric secretion?
fat in the duodenum causes GIP release which decreases gastric secretion and parietal HCL secretion
how does histamine increase gastric secretion?
histamine binds to its receptor which activates Gs.
This protein converts ATP to cAMP which in turn activates the K/H ATPase.
this releases H out of the cell = decrease in PH
what converts inactive trypsinogen to active trypsin?
enterokinase
where is bicarbonate released from?
brunner gland duct cells
