GI Physiology For Lab

2 Digestive Enzymes (fats in yellow, proteins in green, and sugars in red) Salivary glands  -amylase Lipase Stomach pepsin Lipase Liver Lipase Duodenum sucrase maltase lactase Pancreas amylase trypsin chymotrypsin carboxypeptidase Lipase

3 Digestive Hormones and Substances Stomach gastrin Intrinsic factor HCl Prostaglandins Mucous Duodenum Secretin CCK GIP Motilin Pancreas Glucagon Insulin Somatostatin Bicarbonate Liver Bile

4 The Activities of Major Digestive Tract Hormones Figure 24.22

5 OrganRegion of the Organ SubstancesFunction PancreasAcinar cellsAmylase (enzyme)Breaks down starch and carbohydrates into glucose Acinar cellsLipase (enzyme)Breaks down fat into fatty acids Acinar cells Protease enzymes (trypsin, chymotrypsin, carboxypeptidase) Breaks down proteins into amino acids and also kills intestinal parasites and bacteria Acinar cellsBicarbonate (not an enzyme)Raises pH in duodenum Islet of Langerhans; Alpha cellsglucagon (hormone) Causes glycogenolysis, the process which breaks down glycogen into glucose to raise blood glucose. Also causes gluconeogenesis to make new glucose molecules Islet of Langerhans; Beta cellsinsulin (hormone) Removes glucose in bloodstream and brings it into cells. Lowers blood glucose levels. Islet of Langerhans; Delta cellsSomatostatin (hormone)Inhibits digestive (GI) system Liver Bile (a detergent) Emulsifies fat Lipase Breaks down fat Salivary glands Amylase (enzyme)Breaks down starch and carbohydrates into glucose Lipase Breaks down fat Stomach Mucous (not an enzyme)Protect the stomach lining LipaseBreaks down fat Prostaglandins (not an enzyme)Protect the stomach lining Parietal cellsHCl (not an enzyme)Allows Pepsinogen to be converted to pepsin, and it also kills bacteria Parietal cellsIntrinsic factor (not an enzyme) Allows Vit B12 to be absorbed, which is needed to make RBCs. Without it, you get megaloblastic (pernicous) anemia. Chief cellsPepsinogen --> pepsin (enzyme)Breaks proteins into amino acids G cellsGastrin (hormone)Tells parietal cells to secrete HCl Duodenum Secretin (hormone)Tells pancreas to secrete bicarbonate CCK (hormone) Tells pancreas to secrete proteases and lipase, and tells gallbladder to release stored bile (stimulates fat and protein digestion) K cells GIP (hormone)Tells pancreas to release insulin, lipase, and glucagon Motilin (hormone)Initiates peristalsis and tells Chief cells to secrete pepsinogen Maltase, Lactase, Sucrase (enzymes)Break down complex carbohydrates into glucose

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