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Unformatted text preview: HUMAN SYSTEMS QUESTION 1979: L. PETERSON/AP BIOLOGY Describe the structure and function of the stomach, pancreas, and small intestine as digestive and endocrine organs in the human. (For each organ, include the relevant cell types and their functions.) STANDARDS: [1 point for each statement unless otherwise indicated] Stomach (max. 7 points) STRUCTURE: Regions = cardiac, fundic, pyloric / pyloric sphincter (1 pt. for 2 of 3) Layers of muscle; thick walls Presence of RUGAE (cellular composition = histology) DIGESTIVE FUNCTION: Mention chief cells and parietal cells OR Name and function of chief cells - secrete renin, lipase, pepsinogen Name and function of parietal cells - secrete HCl Presence of mucous coat protects the stomach Function of HCl = aids protein digestion OR converts pepsinogen to pepsin Pepsin - produced in inactive form to protect OR its function in protein digestion Churning aids mechanical digestion Absorption of alcohol, etc. in stomach ENDOCRINE FUNCTION: Name and function of gastrin = stimulates production of digestive juice Presence of Food = stimulus for gastrin release Factors such as stress effects gastrin/stomach function Small Intestine (max. 7 points) STRUCTURE: Increased surface area by folds or villi or microvilli Structure of villi = blood vessels, lymph Regions = duodenum, jejeunum, ileum DIGESTIVE FUNCTION: Name 3 enzymes from intestinal glands (peptidases, sucrases, enterokinase, lipase, amylase, nuclease) Function of each enzyme (max. 2) Bile released in small amounts plus: a) produced in the liver or b) stored in gall bladder or c) emulsifier Site of most absorption Mechanical absorption of long fatty acids Peristalsis Change in pH ENDOCRINE FUNCTION: Secretin /function = stimulates release of alkaline secretions by pancreas Enterogasterone /function = inhibits stomach Cholecystokinin /function = stimulates gall bladder to release bile Pancreozymin /function = stimulates pancrease to secrete digestive enzymes Enterokinin /function = stimulates intestinal glands to secrete enzymes Pancreas (max. 7 points) STRUCTURE: Connects to small intestine by pancreatic duct Comprised of exocrine and endocrine cells DIGESTIVE FUNCTION: Secretion of pancreatic juice and digestive function of enzyme mixture OR Name 3 enzymes in pancreatic juice: amylase, trypsinogen, chymotrypsin, carboxypeptidase, lipase Function of each pancreatic enzyme (max. 2) Secretion of bicarbonate ions to neutralize ENDOCRINE FUNCTION: Mention of Islets of Langerhans - function in glucose metabolism Alpha cells secrete glucagon Glucagon stimulates liver to convert glycogen to glucose Beta cells secrete insulin Insulin stimulates uptake of glucose by cells HUMAN SYSTEMS QUESTION 1982...
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