Physiology and Gastric secretions Flashcards
What is enterohepatic circulation?
What is the endocrine function of the pancreas?
A cells - glucagon
B cells - Insulin
What is the exocrine function of the pancreas?
Duct cells - bicarbonate
Acinor cells - pro enzymes and zymogens
What is the first stage of gastric secretion, the cephalic phase?
Sight, smell and taste activates the vagus nerve which stimulates parietal cells to release HCL
It also stimulates chief cells to release pepsinogen
What happens in the second phase of gastric secretions, the gastric phase?
Physical distension activates the vagus nerve causing HCL released from parietal cells and pepsinogen release from chief cells.
Peptides from proteins also stimulate the G cells to release gastrin
Low PH stimulates D cells to release somatostain which inhibits parietal cells
What happens in the third phase of gastric secretions, the intestinal phase?
Chyme with a low PH enters the duodenum and inhibits the vagus and causes local neural inhibition. CCK also inhibts
This duodenum has two more effects:
1) Low PH - Secretin - pancreatic enzymes
2) Fat - CCK - Bile from gall bladder
What is a parietal cell?
What activates a parietal cell?
ACH via M3
Histamine via H2
Gastrin via CCK
What inhibits a parietal cell?
Prostaglandins
What does a parietal cell do and where are the found?
Release HCL and in the fundus and body
What does a chief cell do and where are the found?
Release pepsinogen which is converted to pepsin by HCL
All over
What does a G cell do and where are the found?
Releases gastrin which activates PC
Antrum
What does a D cell do?
Releases somatostatin which inhibits G cells
All over but mainly antrum
