Bile Secretion and Gall Stone Disease Flashcards
What kinds of bile flow are there?
bile acid dependent or bile acid independent.
dependent: hepatocytes secrete bile into ducts and water follows the osmotic gradient.
Independent: ducts secrete bicarb and mucin fluid into the ducts in a secretin/CCK-mediated pathway
Roles of the gallbladder
- store bile when the body is fasting
- release bile in response to fat consumption
- concentrate stored bile
Main types of gallstones
cholesterol stones (enveloped shaped) and bilirubin stones
Bilirubin metab
Heme from RBCs and muscles converted to biliverdin, CO, and Fe3+ by heme oxygenase. biliverdin is converted to bilirubin and is transported in the serum associated with albumin (unconjugated bilirubin)
Liver takes up bilirubin and binds it to Y protein.
Bilrubin + Y protein go to the endoplasmic reticulum.
UGT1A1 addes side chains to bilirubin –> water soluble and ready for excretion.
Conjugated bilirubin is excreted in the bile. Bacteria in the bowel convert conjugated bilirubin to stercobilinogen/urobilinogen. Some excteted in the urine. Stercobilinogen is oxidized to stercobilin
Gilbert’s syndrome
UGT1A1 doesn’t work- unconjugated bilirubinemia. dangerous in neonates. can’t give these pts ironitecan
What are bile acids
made by hepatocytes from cholesterol and then conjugated with amino acids. amphipathic detergents. important for helping fat digestion via emulsification and incr. surface area; incr. absorption of fat soluble vitamins; decr. bacterial overgrowth in the small intestine
types of bile acids
cholic and chenodeoxycholic acid. bacteria convert bile acids to secondary (bad) bile acids deoxycholic and ithocholic acids– toxic and lithogenic.
what is the enterohepatic ciculation of bile acids
bile acids made by liver, stored in gall bladder, released in gut, reabsorbed and returned to liver via protal vein.
risks and types of gallstones disease
risks: female, overweight, pregnant, OCPs, Native American, sudden weight loss, hemolytic anemias
types: yellow cholesterol stones with Ca.
black calcium bilirubinate from chronic hemolysis
brown stones from bacterail action on bile
when do cholesterol stones occur in the gallbladder?
- Oversaturation with cholesterol or not enough bile acids: obesity, high fat diet, acute weight loss, liver disease
- Seeding of a stone (cholesterol monohydrate crystal nucleation)- from bacterial or mucin seed
- gallbladder stasis: fasting, TPN
Clinical presentation of gallstones
usually asymptomatic- no tx needed
others: RUQ epigastric pain post-prandially, often associated with nausea and vomiting. lasts 1-6 hrs.
Complications of gallstones
acute cholecystitis, bile duct obstruction and jaundice, infection, gallstone pancreatitis
Dx and Tx of gallstone disease
Dx: ultrasound
Tx: none if asymptomatic. If symptomatic, do elective cholecystectomy. Or, give URSODIOL if pt not gandidate for surgery. works better with less calcium, small stones, if gallbladder fills and empties well.
What is acute cholecystitis?
acute infection/inflammation of the gallbladder, usually due to blockage of the cystic duct by a gallstone. If bacteria grow, you may see abscesses, fever, chills, peritonitis.
This is a surgical emergency and requires immediate cholecystectomy
Dx of acute cholecystitis
biliary cholic and RUQ pain
exam: RUQ pain, rebound tenderness.
U/S shows gallstones and sludge, thickened distended bladder.
may do a TC99 taged HIDA with nonvisualization of gallbladder with contrast going from liver into the bowel.
Tx: cholecystectomy. give abx, IV fluids, pain meds
