revision Flashcards
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which cells of the stomach secrete HCl and intrinsic factor?
parietal cells
which cells of the stomach secrete pepsinogen?
chief cells
Gastric secretion can be divided into which three phases that cause the gastric mucosa to secrete gastric juice:
- cephalic
- gastric
- intestinal
describe the cephalic phase causing gastric juice secretion
The cephalic phase occurs before food enters the stomach and is stimulated by the sight, smell, thought or taste of food.
describe the gastric phase causing gastric juice seretion
The gastric phase stimulates gastric activity by stretching the stomach and raising the pH of its contents which leads to the release of hydrochloric acid (HCl) by the parietal cells.
describe the intestinal phase of gastric secretion
The intestinal phase is stimulated by stretching of the duodenum due to chyme entering from the stomach.
what factors increase HCl production?
vagal stimulation
gastrin
histamine
what factors decrease HCl production?
- sympathetic stimulation e.g. anxiety
- low gastric pH
- CCK
- GIP
- secretin
- PPIs
- Histamine receptor antagonists
- acetylcholine receptor antagonists
what stimulates CCK release?
The presence of fatty acids or amino acids in the chyme stimulates CCK release
what stimulates secretin release?
Released into the intestinal lumen in response to low duodenal pH caused by gastric acid in the chyme from the stomach.
where are vitamin B12 and bile salts absorbed?
ileum of small intestine
