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Gastrointestinal Physiology (D cells (Found in the pancreatic islets and…
Gastrointestinal Physiology
Enterochromaffin-like cells (ECL)
Synthesise and secrete histamine
Stimulated by
Gastrin
Histamine acts on the H2 receptors to increase H+ secretion
G Cells
Produce
Gastrin
Stimulates parietal cells to produce HCL
Stimulates ECL cells to secrete histamine
G cells are stimulated by Gastrin releasing peptide (GRP) - Not ACh like the other digestive cells
Found in the antrum of the stomach
Chief Cells
Secrete
Pepsinogen
which is converted into pepsin then used for protein digestion
S cells
Secretes
Secretin
in response to reduced pH in the stomach
Secretin increases bicarbonate production by the pancreas
The bicarbonate neutralises stomach acid allowing pancreatic enzymes to function
D cells
Found in the pancreatic islets and mucosa of the GI tract
Secrete
Somatostatin
Somatostatin reduces gastric acid and pepsinogen secretion
Reduces pancreatic and small intestine fluid secretion, gall bladder contraction and insulin and glucagon release
I cells
In the duodenum and jejunum
Secrete
cholecystokinin
which increases pancreatic secretion, gall bladder contraction and reduces gastric emptying
Stimulated by fat and protein products from the stomach
Parietal cells
Produce
HCL
in response to gastrin secretion
Via a H+/K+-ATPase pump
Synthesis intrinsic factor
K cells
In the duodenum and jejunum
Secrete
Gastric inhibitory peptide (GIP)
GIP reduces gastric acid production
Mediates the ideal brake rifles which delays gastric emptying to prevent unabsorbed nutrients entering the lower ilium; is triggered by high levels of fat