Digestion Hormones
Intestinal gastrin: Stimulus for production
Acidic and partially digested food in the duodenum
Secretin: Stimulus for production
Acidic chyme and partially digested proteins/fats
Histamine: Activity/Function
Activates parietal cells to release HCl
Vasoactive Intestinal Peptide (VIP): Site of production
Enteric neurons
Serotonin: Activity/Function
Causes contraction of stomach muscle
Vasoactive Intestinal Peptide (VIP): Stimulus for production
Chyme containing partially digested foods
Intestinal gastrin: Site of production
Duodenal mucosa
Motilin: Site of production
Duodenal mucosa
Cholecystokinin (CCK): Site of production
Duodenal mucosa I cells
Secretin: Site of production
Duodenal mucosa S cells
Motilin: Stimulus for production
Fasting - periodic release occurs every 1.5-2 hours by neural stimuli
Cholecystokinin (CCK): Stimulus for production
Fatty chyme and partially digested proteins
Gastric inhibitory peptide (GIP): Stimulus for production
Fatty chyme, amino acids, and glucose
Gastrin: Stimulus for production
Food (partially digested proteins) in stomach via chemical stimulation Ach released by nerve fibers
Histamine: Stimulus for production
Food in stomach
Serotonin: Stimulus for production
Food in stomach
Somatostatin: Stimulus for production
Food in stomach Stimulation by sympathetic nerve fibers
Gastrin: Activity/Function
Increases HCl secretion and stimulates gastric emptying Stimulates contraction of intestinal muscle Relaxes the ileocecal valve Stimulates mass movements of colon
Gastric inhibitory peptide (GIP): Activity/Function
Inhibits HCl production Stimulates insulin release
Secretin: Activity/Function
Inhibits gastric gland secretion and gastric motility during gastric phase of secretion Increases output of pancreatic juice rich in bicarbonate ions Potentiates CCK action Increases bile output
Somatostatin: Activity/Function
Inhibits gastric secretion of all products Inhibits secretion of pancreatic juice Inhibits GI blood flow thus inhibiting intestinal absorption Inhibits contraction and bile release
Cholecystokinin (CCK): Activity/Function
Inhibits stomach secretory activity Potentiates secretin actions Increases output of pancreatic juice Stimulates gallbladder to contract and expel bile Relaxes sphincter to allow entry of bile and pancreatic juice into duodenum
Gastric inhibitory peptide (GIP): Site of production
K cells of the Duodenal mucosa and Jejunum
Motilin: Target organs
Proximal duodenum
Vasoactive Intestinal Peptide (VIP): Target organs
Small intestine Pancreas Stomach
Vasoactive Intestinal Peptide (VIP): Activity/Function
Stimulated buffer secretion from small intestine Dilates intestinal capillaries Relaxes intestinal smooth muscle Increase secretion of pancreatic juice Inhibits acid secretion in stomach
Intestinal gastrin: Activity/Function
Stimulates gastric glands and motility of the stomach
Motilin: Activity/Function
Stimulates migrating motor complex
Histamine: Target organs
Stomach
Intestinal gastrin: Target organs
Stomach
Serotonin: Target organs
Stomach
Gastric inhibitory peptide (GIP): Target organs
Stomach Pancreas (beta cells)
Cholecystokinin (CCK): Target organs
Stomach Liver Pancreas Gallbladder Hepatopancreatic sphincter
Secretin: Target organs
Stomach Pancreas Liver
Somatostatin: Target organs
Stomach Pancreas Small intestine Gallbladder Liver
Serotonin: Site of production
Stomach mucosa
Histamine: Site of production
Stomach mucosa ECL cells
Gastrin: Site of production
Stomach mucosa G cells
Somatostatin: Site of production
Stomach mucosa and duodenal mucosa
Gastrin: Target organs
Stomach parietal cells Small intestine Ileocecal valve Large intestine