Major Secretions of the Digestive System:
(name; enzyme/aid/hormone; source; function)
- Amylase I (ptyalin or alpha-amylase): salivary enzyme; salivary glands; begins carbohydrate digestion to disaccharides
- Amylase II: pancreatic enzyme; pancreas; finishes digestion of polysaccharides to disaccharides
- Bile: digestive aid; liver; emulsifies fats and aids in absorption of fatty acids as well as the fat-soluble vitamins (A, D, E, K)
- Bombesin: hormone; intestine; controls the release of gastrin and cholecystokinin and helps control appetite
- Cholecystokinin (CCK): hormone; duodenum; stimulates the gallbladder to contract and release bile, stimulates the release of pancreatic digestive enzymes and helps control the appetite
- Disaccharides (sucrase, lactase, maltase): intestinal enzymes; intestines; digests disaccharides to monosaccharides
- Enterokinase: intestinal enzyme; intestines; activates trypsinogen to trypsin
- Gastric Inhibitory Peptide (GIP): hormone; duodenum; inhibits the secretion of gastric acid
- Gastrin: hormone; stomach and duodenum; stimulates gastric glands to secrete gastric juices
- Hydrochloric acid (HCl): digestive aid; stomach; helps to disseminate proteins and kills harmful microorganisms in food
- Intrinsic factor: digestive aid; stomach; vital for the absorption of Vitamin B12
- Lipase: pancreatic enzyme; pancreas; digests fats to fatty acids to glycerol
- Motilin: hormone; intestine; causes accelerated movement of food along its length (peristalsis)
- Mucins: glycoproteins; salivary glands; responsible for the lubricating properties of mucous secretions of goblet cells and glands throughout the body
- Mucus: digestive aid; entire digestive tract; softens and lubricates food to ease its passage through the tract
- Neurotensin: hormone; intestine; inhibits the movement of the intestine slowing down the movement of food along its length
- Pepsin: gastric enzyme; gastric glands; begins digestion of protein
- Peptidases: intestinal enzyme; intestines; digests peptides to amino acids
- Proteases (trypsin and chymotrypsin): pancreatic enzymes; pancreas; digests proteins to peptides
- Secretin: hormone; duodenum; stimulates the pancreas to secrete sodium bicarbonate
- Vasoactive Intestinal Peptide (VIP): hormone; intestine; causes diarrhea and lowers blood pressure
