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34 Cards in this Set
- Front
- Back
What granules and what organelle are seen in volume in the pancreas?
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Zymogen granules and lots of ER
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What is the most important hormone governing pancreatic ENZYME secretions? What does it bind? What is the second most important?
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CCK
It binds CCK-A 2nd most important is ACh |
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What other receptors are present on the pancreas besides the CCK-A receptor?
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Secretin and VIP receptors--not as important as CCK and ACh
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What are some active enzymes found within the pancreas? How does it work?
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LIPASE--needs colipase to work and colipase is cleaved to be active only by trypsin
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True/False: If you change your diet, then the pancreas will change what enzymes it secretes.
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TRUE--it will adjust to produce either more lipase or more amylase
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What percent of bicarb is secreted by the duodenum itself?
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40% from crypts and surface cells
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True/False: The pancreatic primary secretion is analogous to salivary primary secretion
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FALSE--most of the pancreatic secretion is made by the ducts
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What happens in the pancreatic secretions at high flow rate?
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DRAMATIC increase in bicarb
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How are ions secreted from the acinar cells?
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Na+/K+ pump builds Na+ outside the cell in the interstitial space
Na/K/Cl cotransporter pulls in all three and is driven by the Na+ gradient K+ escapes back to interstitium through its channel Cl- is then secreted into the acinus through an apical Cl- channel This Cl- buildup in the acinus creates a gradient that flows back down into the cell through a BICARB/Cl- EXCHANGER |
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What transporter is critical in pancreatic secretions in Cl- transport?
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CFTR
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Are pancreatic ducts permeable to water?
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YES
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What is the tonicity of the bicarb solution in the acinus?
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Isotonic
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How does gastrin come into play in the pancreas?
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It binds the CCK-A receptor that is similar to its normal CCK-B receptor and stimulates secretion
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What occurs to stimulate the pancreas during the duodenal/intestinal phase?
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Fat and protein stimulates I cells to make CCK
Protons from stomach stimulate S cells to release secretin which pushes water out into the ducts? |
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Which is more important to stimulate pancreatic activity--food or acid?
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FOOD--acidity never really gets low enough
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What are the most important systemic regulators of pancreatic secretions?
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pH<4.5 and FA's cause release of secretin from S cells in the duodenum; fat, peptides, and amino acids cause CCK release from I cells of the duodenum
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Bile makeup.
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Gallbladder bile is much more concentrated than hepatic bile in all respects
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Bile acids that have a 7' Hydroxyl group will be?
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More hydrophilic.
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What is a secondary bile acid and how is it made?
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in the gut--OH group is stripped off and so the bile acid is more hydrophobic
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Where do primary and secondary bile acids get conjugated?
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In the liver--taurine and glycine is added
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Why are bile salts conjugated to amino acids?
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It makes them more soluble--easier to make micelles and fat digestion is more efficient
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How are bile salts transported into the hepatocyte? Out?
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By sodium dependent co-transport
Primary active transport |
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TRUE/FALSE: CFTR is not important in bile ducts.
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FALSE
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Secretin, glucagon, and VIP receptors in bile duct transporters cause what?
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Increase in cAMP that causes CFTR channels to transport more Cl-
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What is enterohepatic circulation?
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Bile salts are reabsorbed in the terminal ileum--bacteria have stripped off 7'OH group and stripped off AA conjugation
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Why do we need a gallbladder?
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Bile salts are excellent detergents that solubilize fat--if they are stored in the gallbladder then we can minimize losses and prevent exposure
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How is bile concentrated?
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Na/Cl exchanger and H+/Bicarb exchanger--salt is moved across cell to BL membrane and into the interstitium and draws water with it
Tight junctions = high resistance epthelium |
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Is the tight junction really tight?
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NO--we are talking about electrical resistance and this is a leaky junction that allows water through and therefore only a small amount of salt is needed to be moved across to draw a lot of water
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True/False: Vagal stimulation has an effect on bile production
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TRUE--it stimulates gallbladder contraction
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Gall stones occur why?
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When there is an imbalance in the levels of cholesterol vs. bile salt.
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How is bilirubin metabolized?
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It is a breakdown product of hemoglobin
It is conjugated to plasma albumin to be carried in the blood to the liver It is taken up in the liver and binds GLUCURONIC ACID to become more soluble It is secreted into bile and ends up in the gut It is deconjugated by bacteria in the gut into bilirubin Bilirubin is converted to urobilinogen Some urobilinogen is reabsorbed to portal circulation(THE IMPORTANT PART OF THIS PROCESS) and this goes to the kdineys to be excreted in the urine |
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Why is urobilinogen important?
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It is eliminated partially in the kidneys
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What are the three types of jaundice?
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Pre-hepatic i.e. increased hemolysis; Sickle cell anemia, thalassemia and hemolytic disease of the newborn
Intra-hepatic i.e. decreased conjugation or decreased uptake of bilirubin; hepatitis, cirrhosis, liver cancer; neonatal jaundice Post-hepatic i.e. obstruction of bile flow; cholelithiasis, structural disorders of the bile duct, obstruction due to tumors |
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What eventually happens to urobilinogen?
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It is oxidised to urobilin and stercobilin
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