Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
SSN SBPM Workshop~ Exam 5 Multiple Choice Questions **Last year’s handouts are available at http://cpmcnet.columbia.edu/student/ssn/sbpmd/block5.htm 1. Which GI hormone is released in response to mechanical stretch? A. CCK B. Secretin C. Gastrin D. GIP E. Motilin 2. Joe goes to famiglia and eats a delicious slice of Sicilian pizza. Less than 20 minutes later in anatomy lab he strongly feels the urge to defecate. What is the most likely mechanism? A. B. C. D. Fundo-sigmoidal reflex Gastro-colic reflex Ileo-colic reflex Flatulative reflex 3. Chronic administration of which of the following types of drugs would lead to a sustained increase in serum gastrin levels? A. B. C. D. Proton Pump Inhibitor Anticholinergic H2 receptor antagonist Beta blocker 4. The delivery of chyme into the proximal small intestine will A. Increase gastric acid secretion B. Decrease pancreatic bicarbonate secretion C. Increase gastric emptying of solids D. Decrease circulating CCK levels 5. Which one of the following statements is correct? A. Pepsin is inactivated at a pH of 3 and below B. Gastric acid secretion is greatest during the cephalic phase of digestion C. Somatostatin increases antral G cell gastrin release D. Maximal acid output may be increased in a patient with duodenal ulcer disease 6. Pyruvate is converted to acetyl CoA in the: A. B. C. D. E. Mitochondrial matrix Cytosol Smooth endoplasmic reticulum Rough endoplasmic reticulum Nucleus 7. When insulin levels are elevated, PFK2 acts as a ___________, levels of fructose-2,6bisphosphate are ___________ and glycolysis is ____________. A. B. C. D. E. Phosphorylase; low; inhibited Kinase; high; inhibited Phosphorylase; low; stimulated Kinase; high; stimulated Phosphorylase; high; inhibited 8. After secretion of trypsinogen into the duodenum, the enzyme is converted to its active form, trypsin, by: A. B. C. D. E. Enteropeptidase Procarboxypeptidase Pancreatic lipase Previously secreted trypsin An alkaline pH 9. The transport protein responsible for entry of glucose into the intestinal enterocyte is called: A. B. C. D. E. GLUT-2 GLUT-5 SGLT1 SGLT2 SGLT5 10. Which of the following sugars is absorbed from the small intestine by facilitated diffusion? A. B. C. D. E. Glucose Galactose Fructose Sucrose A and B 11. Severe inflammation of the ileum may be accompanied by: A. B. C. D. E. Decreased vitamin B12 absorption Decreased bile acid pool size Increased colon absorption of water Increased absorption of dietary fatty acids A and B 12. Which is not a final destination of amino acid carbons? A. B. C. D. E. Glucose Urea CO2 Ketones Tissue Protein 13. Which of the following enzymes catalyzes an irreversible reaction in Amino Acid metabolism? A. Glutamate Dehydrogenase B. Transaminases C. Glutamate Synthetase 14. Which of the following enzymes is not involved in the production of ammonia? A. B. C. D. E. Glutamate Dehydrogenase Amino Acid Oxidase Transaminase Urease Threonine Dehydrogenase SSN SBPM Workshop~ Exam 5 Answers to Multiple Choice Questions 1. C 2. B 3. A. Gastric acid secretion by parietal cells occurs in response to neural (acetylcholine), hormonal (gastrin), and paracrine (histamine) excitatory inputs. Secretion of the parietal cell involves the H+-K+-ATPase actively pumping H+ out of a cell in exchange for K+ entering the cell. Inhibition of pump activity leads to a prolonged increase in gastric pH and the removal of the inhibitory effect of low pH (<3.0) on gastrin release. 4. C The delivery of food into the proximal small intestine is accompanied by the appearance of segmenting intestinal contractions. It also initiates neural reflexes and the release of hormones that affect a variety of GI processes. It's inhibitory to gastric secretion and emptying, stimulates pancreatic and hepatobiliary secretions (CCK, secretin), and increases small intestine segmentation. The latter is responsible for mixing chyme with bile and the digestive enzymes. 5. D Gastric juice contains a number of secretions including HCl, intrinsic factor, pepsinogen, water, and electrolytes. Gastric secretion can be studied during the interdigestive (basal phase) or the digestive (cephalic, gastric, and intestinal phases of acid secretion) periods. Increased acid output is the result of neural (ACh), hormonal (gastrin), and paracrine (histamine) stimuli acting on the oxynitic cell. Feedback regulation )inhibition) of acid secretion occurs as the result of ion-stimulated release of somatostation from paracrine cells located near the gastrin-containing antral G cells and as the result of the presence of chyme in the small intestine. The latter limits acid secretion via neural and hormonal pathways. Removal of the intestinal inhibitory feedback leads to increased acid output. 6. A Pyruvate dehydrogenase is a mitochondrial enzyme 7. D High levels of insulin activate intracellular phosphatases. Dephosphorylated PFK2 is most active as a kinase, so it phosphorylates fructose-6-phosphate to F-2,6-P. Increased levels of F-2,6-P in turn allosterically activate phosphofructokinase-1, which is the key glycolytic regulatory enzyme. This should make sense because insulin--secreted in the fed state--stimulates the conversion of ingested carbohydrate into triglyceride by converting glucose to pyruvate and onward. 8. A 9. C 10. C 11. E 12. B The Nitrogen from amino acids becomes urea NOT the carbons 13. C The irreversibility of the glutamate synthetase reaction limits ammonia toxicity, especially in the brain. 14. C SSN SBPM Workshop~ Exam 5 Short Answer Questions Note: These questions may not be similar to the on-line short answer questions for your exam. The purpose of these questions is to explain topics in more detail than is allowed by the Multiplechoice format. Also, these questions offer an opportunity to go over some topics that the SSN teachers do not have time to teach during the SSN session. 1. Acidification of the duodenal mucosa results in… The main response to acidic fluid in the duodenum is the stimulation of secretin, which stimulates both the gall bladder & pancreas to release bicarbonate. Secretin also slows gastric emptying to allow time for the contents of the small intestine to be neutralized before even more acidic stuff from the stomach enters. 2. Explain why, after a night of many beers, a person can become hypoglycemic the next morning (helping to explain some of their righteous hangover). Hint: One molecule of ethanol is metabolized in the body to one acetyl CoA, and in the process, forms 2 molecules of NADH. High levels of NADH are going to build up with ethanol ingestion. In this heavily reducing environment, there will be a tendency for pyruvate to be converted to lactate (remember that a buildup of NADH slows glycolysis because free NAD+ is needed for the glyceraldehyde-3-P dehydrogenase reaction). Also, lactate itself, a gluconeogenic precursor, will not be converted back to pyruvate because of all the excess NADH. This isn't the only reason why alcohol can lead to hypoglycemia, but it is an important contributing factor. 3. What is the difference between feed-forward and feed-back regulation? Why is one more common in disposal pathways? In feed-back regulation, a downstream product of the pathway inhibits the initiation of the pathway. In feed-forward, the downstream product stimulates the pathway. Disposal pathways (such as the urea cycle) often involve feedforward stimulation, because as the amount of substrate increases, so does the need for its disposal. Production pathways usually use feed-back inhibition to limit the amount made.