Gastro 16 - Biliary Tract Flashcards
Where is bile made?
In the liver by hepatocytes.
Describe the flow of bile from the liver to the duodenum.
Bile flows from the left and right hepatic ducts into the common hepatic duct. Then it flows into the cystic duct into the gallbladder, where it is stored. When the gallbladder contracts, bile flows back into the cystic duct to the common bile duct (where the cystic duct and common hepatic duct come together). Then it joins the main pancreatic duct into the ampulla of Vater.
What is the main hormone that causes contraction of gallbladder?
Cholecystokinin. Chole- means bile. Cyst- means bag. Kinin- moving.
What does cholecystokinin do?
Makes the gallbladder contract. Delays gastric emptying. Stimulates pancreatic enzyme secretion.
What is a bile salt?
Bile salts (cation {e.g. Na+} plus a bile acid (oxidized cholesterol like cholic acid, deoxycholic acid, chenodeoxycholic acid). Most bile acids are conjugated w/ glycine (making glycocholic acid) or taurine (making glycocholic acid).
What is the use of bile?
To emulsify lipid particles so it can be digested. Excreting cholesterol and bilirubin. Copper excretion. Bactericidal for the food we ingest.
What is the composition of bile?
Bile salts. Bilirubin (conjugated because unconjugated is not soluble in water). Cholesterol. Phospholipids. Electrolytes.
Where does bilirubin comes from?
From the breakdown of hemoglobin in unconjugated state, where it binds to albumin to be transported to the liver. There, it is conjugated and excreted into the bile.
What does the colon do to the bilirubin excreted in the duodenum?
The colonic bacteria convert it to urobilinogen which is oxidized to stercobilin (making the stool brown) and excreted in the stool. A small amount of urobilinogen is reabsorbed by the gut; this is called enterohepatic circulation. A tiny amount of the reabsorbed uribilinogen is converted to urobilin and excreted in the urine, and is what makes urine yellow.
What would be the three causes of increased unconjugated hyperbilirubinemias?
Increased bilirubin production. Impaired bilirubin uptake and storage. Decreased UDP-GT activity.
What would be three causes of increased bilirubin production?
Hemolytic anemia. Sickle cell disease. Hematoma breakdown.
What would be the two causes of impaired bilirubin uptake and storage?
Viral hepatitis. Drugs.
What would be the three causes of decreased UDP-GT activity?
Gilbert syndrome. Crigler-Najjar syndrome Type I and II. Neonatal physiologic jaundice.
What would be the four causes of conjugated hyperbilirubinemias?
Impaired transport. Biliary epithelial damage. Intrahepatic biliary obstruction. Extrahepatic biliary obstruction.
What would be two causes of impaired transport of conjugated hyperbilirubinemias?
Dubin-Johnson syndrome. Rotor syndrome.
What would be the causes of biliary epithelial damage that would lead to conjugated hyperbilirubinemia?
Hepatitis. Cirrhosis. Liver failure.
What would be three causes of biliary obstruction leading to conjugated hyperbilirubinemia?
Primary biliary cirrhosis. Sclerosing cholangitis. Drugs (chlorpromazine, arsenic).
What would be the four causes of extrahepatic biliary obstruction leading to conjugated hyperbilirubinemia?
Pancreatic neoplasms. Pancreatitis. Cholangiocarcinoma. Choledocholithiasis.
How can we clinically distinguish b/w intrahepatic biliary obstruction vs extrahepatic biliary obstruction in a patient that shows up in the ER with jaundice?
Do a RUQ ultrasound; it will tell you if there is an extrahepatic biliary obstruction.
What is Primary Sclerosing Cholangitis (PSC)?
Disease causing concentric fibrosis of bile ducts; scarring and strictures. “Beads on a string” on ERCP. Mostly men around age 40. Up to 80% have positive pANCA. Associated w/: ulcerative colitis, cholangiocarcinoma.
What is Primary Biliary Cirrhosis (PBC)?
Autoimmune disease, causing T lymphocytes attacking bile ductules within the liver parenchyma. Can cause granulomas and leads ultimately to cirrhosis. 90% are middle-aged women. Positive Anti mitochondrial Ab (AMA). Associated w/ other autoimmune disorders : CREST scleroderma, Sjogren syndrome, Rheumatoid arthritis.
What one particular drug is useful for the treatment of primary biliary cirrhosis And what does it do?
Ursodiol (ursodeoxycholic acid). It is a bile acid that decreases synthesis of cholesterol in the liver, changes the composition of bile and delays progression of PBC. It will not reverse the damage already done, but improves survival by slowing down further damage.
What is the definitive treatment for both Primary biliary cirrhosis and Primary Sclerosing Cholangitis?
Liver transplant.
What is Secondary Biliary Cirrhosis?
Cirrhosis from biliary obstruction secondary to some extrahepatic process blocking biliary outflow.
