questions 2

Pancreatic Enzymes

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Topic updated on 08/20/17 12:48am

Overview
  • Pancreatic enzymes
    • pancreas secretes enzymes required for digestion of carbohydrates, proteins, and lipids
      • carbohydrates
        • pancreas secretes α-amylase in active form
          • digests 1,4-glycosidic bonds of carbohydrates (starch)
      • lipids
        • lipase-colipase
          • pancreas secretes (active) lipase
            • hydrolyzes triglycerides → 1 monoglyceride + 2 fatty acids
            • lipase is inactivated by bile salts
            • pancreas secretes (inactive) procolipase
              • in intestinal lumen, trypsin activates procolipase
                • procolipase (inactive) → colipase (active)
              • colipase displaces inhibitory bile salts
                • permits digestive functions of lipase
        • phospholipase A2
          • pancreas secretes (inactive) phospholipase A2
            • in intestinal lumen, trypsin activates phospholipase A2
          • hydrolyzes phospholipids → lysolecithin + fatty acids
      • proteins
        • pancreas secretes proteases in inactive forms called proenzymes/zymogens
          • trypsinogen 
          • chymotrypsinogen
          • proelastase
          • procarboxypeptidase A/B
        • activation of pancreatic proteases
          • brush-border enterokinase/enteropeptidase activates trypsinogen 
            • trypsinogen (inactive) → trypsin (active)
          • trypsin catalyzes conversion of inactive precursors to active enzymes
            • trypsinogen → trypsin (positive feedback loop
            • chymotrypsinogen → chymotrypsin
            • proelastase → elastase
            • procarboxypeptidase A/B →carboxypeptidase A/B
        • pancreatic proteases hydrolyze dietary protein to absorbable molecules
          • amino acids, dipeptides, tripeptides


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Qbank (1 Questions)

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(M1.GI.31) A 55-year-old woman presents with acute onset abdominal pain radiating to her back, nausea, and vomiting. CT scan suggests a diagnosis of acute pancreatitis. The pathogenesis of acute pancreatitis relates to inappropriate activation of trypsinogen to trypsin. Which of the following activates trypsin in normal digestion? Topic Review Topic

1. Amylase
2. Lipase
3. Cholecystokinin
4. Enterokinase
5. Secretin

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