click below
click below
Normal Size Small Size show me how
GI regulation
Med 1
Thing | About Thing |
---|---|
CCK | I cells of small intestine (CCKa receptors); stimulated by: peptides, AA, and FA; action: contraction of gallbladder and relaxation of sphincter of Oddi, increase pancreatic enzyme/ HCO3, inhibits gastric emptying |
Secretin | S cells of duodenum; stimulated by: H+ and FA in duodenum; action: increases pancreatic and biliary HCO3, decreases gastric H+ |
GIP | K cells of small intestine; stimulated by: FA, AA, and oral glucose; action: increase insulin secretion, decrease H+ |
Ach | Vagus; action: M3 receptor—> Gq—> IP3/ Ca++—> H+; pumps up ECL; blocked by atropine |
Gastrin | G cells of stomach antrum (circulation); stimulated by: peptides and AA, stomach distention via ACh, vagus via GRP; action: CCKb receptor —> Gq—> IP3/ Ca++—> H+; activates ECL more powerfully; increases gastric mucosa |
Histamine | ECL cells; action: H2 receptor—> Gs—> cAMP—> H+; blocked by cimetidine |
Somatostatin | D cells, action: Diffusion—> Gi—> cAMP—> stop H+; inhibits ECL and G cells |
Prostaglandins | action: Diffusion—> Gi—> cAMP—> stop H+; inhibits ECL cells; stimulates mucus production |
VIP | Parasym gangs in sphincters, gallbladder, small intestine; stimulated by: distention and vagus; action: relaxation of intestinal smooth muscle (NO relaxes too) |
Intrinsic factor | Parietal cells of stomach fundus; stimulated by: Gastrin and Histamine via G and ECL cell, vagus via ACH; action: Vit B12 absorption in terminal ileum |
Pepsin | chief cells of stomach (fundus) mucous cells (antrum) as pepsinogen, stimulated by: Vagus, action: Protein digestion |