The digestive system is controlled by both: Nerves, and Hormones
Neuronal control of digestion Autonomic Nervous System SNS PNSDigestive system Digestive system activityactivity
Sympathetic nerves that regulate digestion are: The greater splanchnic nerves The lumbar splanchnic nerves, and The sacral splanchnic nerves
The parasympathetic nerve that regulates digestion are the vagus nerves.
Hormones that control digestion are: Gastrin Secretin Cholecystokinin Glucose insulinotropic peptide (GIP)
Effects of gastrin Stimulates gastric juice secretion Stimulates smooth muscle contraction Relaxation of pyloric sphincter
Effects of secretin Stimulates bicarbonate secretion Stimulates bile production Inhibits gastric juice secretions and gastric motility
Effects of cholecystokinin Stimulates bile release Stimulates pancreatic juice secretion Relaxation of the hepatopancreatic ampulla and opening of hepatopancreatic sphincter
Effects of GIP Stimulates the pancreas to begin release of insulin
The 3 phases of digestive regulation Cephalic phase Gastric phase Intestinal phase
Cephalic Phase Neuronal response: Stimuli that arouse digestion relayed to hypothalamus Nerve impulse initiated in vagus nerve Impulse innervates nerve network of GI tract Contraction of sm ms & secretion of gastric juice promoted
Gastric Phase The stimuli that initiates gastric phase includes: Distension of the stomach Low acidity Presence of peptides
Gastric Phase Neural response: gastric juice secretion & smooth muscle contraction promoted Hormonal response: gastrin production promoted General effect: stomach and small intestine prepare for digestion of chyme , and gastric emptying is promoted
Intestinal Phase Neural response: gastric secretion & gastric motility are inhibited Intestinal secretion, sm ms contraction, bile & pancreatic juice production are promoted
Intestinal Phase Hormonal response: production of secretin, CCK & GIP is promoted General effects : gastric emptying is retarded to allow adequate time for digestion in the SI. And intestinal digestion and motility are promoted.