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Name: ____________________________ Date: ________________ BIOLOGY 12 DIGESTIVE SYSTEM HORMONES Control of Digestive Gland Secretion Generally speaking, the presence of food in digestive system triggers digestive glands to secrete their enzymes. More specifically, _______________ control secretion of specific digestive juices. There are 4 hormones that we will look at: _______________, _____________________, _______________________, and GIP. Secretin CCK CCK Secretin CCK Gastrin Gastrin STOMACH: When food is eaten, _______________ ___________________ in the stomach detect the presence of _____________________________. Other sensory receptors detect that the stomach is distending (i.e. stretching). This causes other stomach cells to release __________________ into the blood. __________________ travels through the blood and finally reaches other cells (takes about 1 minute) in the stomach that produce ___________________ _______________, and stimulates its release. DUODENUM: Most digestion of food occurs in the _____________________. The acid ____________ seeps in from the stomach and is first ____________________. The hormone _____________________, a hormone produced by the small intestine, mediates this neutralization by stimulating the release of ________________ ____________________ by the _______________________. The presence of ______________ ______________ or _____________ ___________ in the duodenum triggers the release of _____________________ (___) which stimulates the release of _______________ ______________ by the ___________________ and _________________ by the ______________________. A fourth hormone, ENTEROGASTRONE (also known as Gastric Inhibitory Peptide, or GIP), released by the small intestine, slows digestion by INHIBITING stomach peristalsis and acid secretion when acid chyme rich in fats (which require additional digestion time) enters the duodenum. Summarize what you know about hormones into the following table: Hormone GASTRIN SECRETIN CCK GIP Released by what part/ in response to what? Acts on what part? What does it do? BIOLOGY 12 DIGESTIVE SYSTEM HORMONES Control of Digestive Gland Secretion Generally speaking, the presence of food in digestive system triggers digestive glands to secrete their enzymes. More specifically, HORMONES control secretion of specific digestive juices. There are 4 hormones that we will look at: GASTRIN, SECRETIN CCK(CHOLECYSTOKYNIN) and GIP. STOMACH: When food is eaten, SENSORY CELLS (RECEPTORS) in the stomach detect the presence of PEPTIDES (PROTEINS). Other sensory receptors detect that the stomach is distending (i.e. stretching). This causes other stomach cells to release GASTRIN into the blood. GASTRIN travels through the blood and finally reaches other cells (takes about 1 minute) in the stomach that produce GASTRIC JUICES , and stimulates its release. Contained in pancreatic juice DUODENUM: Most digestion of food occurs in the DUODENUM The acidic CHYME seeps in from the stomach and is first NEUTRALIZED. The hormone SECRETIN a hormone produced by the small intestine, mediates this neutralization by stimulating the release of SODIUM BICARBONATE (NaHCO3) by the PANCREAS. The presence of AMINO ACIDS or FATTY ACIDS in the duodenum triggers the release of CHOLECYSTOKYNIN (CCK) which stimulates the release of DIGESTIVE ENZYMES by the PANCREAS and BILE by the GALL BLADDER A fourth hormone, ENTEROGASTRONE (also known as Gastric Inhibitory Peptide, or GIP), released by the small intestine, slows digestion by INHIBITING stomach peristalsis and acid secretion when acid chyme rich in fats (which require additional digestion time) enters the duodenum. Hormone GASTRIN SECRETIN CCK GIP Released by what part/ in response to what? upper part of stomach/in response to protein in the stomach Small intestine (duodenum) /Acid chyme from stomach Small intestine (duodenum) /partially digested protein and fat Small intestine/acid chyme rich in fats enter duodenum Acts on what part? What does it do? gastric glands of the stomach Causes secretion of gastric juices Pancreas Liver Gall bladder Pancreas Liver Gall bladder Stomach Causes pancreas to release NaHCO3 and pancreatic enzymes Causes liver to secrete bile and pancreas to secrete pancreatic juice. Inhibits stomach peristalsis and acid secretion (opposes gastrin)
