- half as potent as CCK in causing emptying of gallbladder
- release stimulated by acetylcholine (vagus nerve) in stomach - fired during cephalic
phase and in reflex response
to stretching of stomach wall
- in duodenum and proximal jejunum presence of amino acids and peptides stimulates release
- presence of amino acids and peptides in blood enhance gastrin release in antrum
- binds to CCK-B receptor on parietal cell and causes secretion of HCl
through PIP2 mechanism
- potentiates action of histamine and acetylcholine on parietal cells
- stimulate enterochromaffin-like cells to produce histamine
- if pH falls too low then this will inhibit gastrin release
- stimulates gastric contractility
- promotes constriction of pyloric sphincter
- increases strength of antral contractions
- thereby reduces gastric emptying
- enhances pancreatic secretion during gastric phase
- stimulates chief cells to produce pepsinogen
-
-
14.6.1 Gastrin
| produced in gastric antrum |
pancreatic gastrin (rel tumours) |
| actions: gastric acid secretion; relations with histamine
H2 actions; pepsin secretion |
|
| stimuli for gastrin secretion; H+ negative
feedback |
|
| dysfunction: gastrinoma |
|
|