Functions of the Liver in the Gastrointestinal System
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Questions and Answers

What is a primary function of the liver in relation to the blood from the gastrointestinal tract?

  • To increase the blood flow to the inferior vena cava
  • To serve as a filter between the blood from the gastrointestinal tract and the blood in the rest of the body (correct)
  • To increase the blood pressure in the rest of the body
  • To decrease the blood sugar levels

    • What is the primary source of blood that reaches the liver?

  • Hepatic veins
  • Inferior vena cava
  • Hepatic artery
  • Portal vein (correct)

    • Where does the bile formed in the liver eventually drain into?

  • Intestine (correct)
  • Hepatic veins
  • Inferior vena cava
  • Portal vein

    • What is the average time it takes for blood to pass through the liver lobule from the portal venule to the central hepatic vein?

    <p>8.4 s</p> Signup and view all the answers

    What is the purpose of the sinusoids in the liver?

    <p>To allow for efficient exchange of substances between the blood and hepatic cells</p> Signup and view all the answers

    What happens to the blood during its passage through the hepatic plates?

    <p>It is extensively modified chemically</p> Signup and view all the answers

    What is the reason for portal pressures not increasing linearly with portal flow?

    <p>To prevent fluid loss from the highly permeable liver under normal conditions</p> Signup and view all the answers

    What is the result of increased hepatic pressures in disease states?

    <p>Accumulation of fluid in the peritoneal cavity as ascites</p> Signup and view all the answers

    What type of nerve fibers innervate the intrahepatic portal vein radicles?

    <p>Noradrenergic vasoconstrictor</p> Signup and view all the answers

    What happens to the portal vein radicles when systemic venous pressure rises?

    <p>They are dilated passively</p> Signup and view all the answers

    What is the result of diffuse noradrenergic discharge in response to a drop in systemic blood pressure?

    <p>Constriction of the intrahepatic portal radicles</p> Signup and view all the answers

    What happens to the blood flow through the liver during heart failure?

    <p>It bypasses most of the liver</p> Signup and view all the answers

    What is the primary function of the enzyme glucuronyl transferase in the liver?

    <p>To conjugate bilirubin to glucuronic acid</p> Signup and view all the answers

    What is the main difference between free bilirubin and bilirubin glucuronide in terms of solubility?

    <p>Bilirubin glucuronide is more water-soluble</p> Signup and view all the answers

    Where is the enzyme glucuronyl transferase primarily located in the liver cell?

    <p>Smooth endoplasmic reticulum</p> Signup and view all the answers

    What is the role of multidrug resistance protein-2 (MRP-2) in the liver?

    <p>To transport bilirubin glucuronide into the bile canaliculi</p> Signup and view all the answers

    What is the fate of most of the bilirubin glucuronide produced in the liver?

    <p>It is transported into the bile ducts</p> Signup and view all the answers

    What is the significance of the binding of bilirubin to albumin in the blood?

    <p>It reduces the excretion of bilirubin in the urine</p> Signup and view all the answers

    What is the primary driving force for the initial formation of canalicular bile?

    <p>Active secretion of bile acids</p> Signup and view all the answers

    What is the approximate ratio of bile acids:phosphatidylcholine:cholesterol in canalicular bile?

    <p>10:3:1</p> Signup and view all the answers

    What happens to the tight junctions between adjacent hepatocytes during bile formation?

    <p>They remain permeable to allow passive diffusion</p> Signup and view all the answers

    What is the consequence of deviations from the normal bile acids:phosphatidylcholine:cholesterol ratio in canalicular bile?

    <p>Cholesterol precipitation and gallstone formation</p> Signup and view all the answers

    What is the fate of conjugated bilirubin in bile duct obstruction?

    <p>It regurgitates into the blood</p> Signup and view all the answers

    What is the function of phosphatidylcholine in bile?

    <p>It forms mixed micelles with bile acids and cholesterol</p> Signup and view all the answers

    What is the main function of the gallbladder in relation to bile?

    <p>To store and concentrate bile</p> Signup and view all the answers

    What is the approximate percentage of solids in gallbladder bile?

    <p>10-12%</p> Signup and view all the answers

    What happens to the sodium ion concentration in bile as it becomes more concentrated?

    <p>It increases</p> Signup and view all the answers

    What is the pH of gallbladder bile compared to hepatic duct bile?

    <p>It is less alkaline</p> Signup and view all the answers

    What is the result of clamping the bile duct and cystic duct?

    <p>Intra-biliary pressure increases and bile secretion stops</p> Signup and view all the answers

    What is the composition of hepatic bile in terms of water content?

    <p>97% water</p> Signup and view all the answers

    What is the main reason for the reabsorption of some bile pigments and urobilinogens in the portal circulation?

    <p>The action of bacteria in the intestine on bilirubin</p> Signup and view all the answers

    At what level of plasma bilirubin is jaundice typically detectable?

    <p>2 mg/dL (34 μmol/L)</p> Signup and view all the answers

    What is the effect of hemolytic anemia on bilirubin levels in the blood?

    <p>Excess production of bilirubin</p> Signup and view all the answers

    What is the fate of small amounts of urobilinogens that enter the general circulation?

    <p>They are excreted in the urine</p> Signup and view all the answers

    What is the main difference between conjugated bilirubin and urobilinogens?

    <p>Urobilinogens are formed in the intestine</p> Signup and view all the answers

    What is the effect of intrahepatic or extrahepatic bile duct obstruction on bilirubin levels?

    <p>Disturbed secretion of conjugated bilirubin into the bile canaliculi</p> Signup and view all the answers

    What is the role of the intestinal mucosa in the reabsorption of bilirubin and urobilinogens?

    <p>It is impermeable to conjugated bilirubin but permeable to unconjugated bilirubin</p> Signup and view all the answers

    What is the significance of the free bilirubin level in the blood?

    <p>It rises in cases of disturbed intracellular protein binding or conjugation</p> Signup and view all the answers

    What is the result of the enterohepatic circulation of bilirubin and urobilinogens?

    <p>Reabsorption of some bile pigments and urobilinogens into the portal circulation</p> Signup and view all the answers

    What is the primary cause of hyperbilirubinemia in the blood?

    <p>All of the above</p> Signup and view all the answers

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