Major Secretions
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 and stimulates the release of pancreatic digestive enzymes as well as helping to 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
This page was updated in December 2005.
