Flashcards in Phys Bile Secretion and Gall Bladder Function Deck (22):
Describe resting condition of biliary system
sphincter of Oddi is closed. Bile flows from liver to gallbladder, which expands.
contents of bile from liver
contents of bile modified by secretin
What happens in gall bladder?
Removal of Na+, Cl-, HCO3-, H2O
opens sphincter of Odi, contraction of gallbladder
How much of bile acid is lost in stool?
Where is cholesteral/bile salts reabsorbed
How are bile salts reabsorbed?
K-dependent manner in ileum
2 primary bile acids & why is primary a thing?
Primary bile acids are synthesized by the liver & nowhere else.
2 secondary bile acids
deoxycholic acid (from cholic acid)
lithocholic acid (from chenodeoxycholic acid)
2 amino acids with which to make bile salts
why is it important to make a salt or an acid?
salt = hydrophilic/amphiphilic so stays in lumen
acid = more hydrophobic, so reabsorbed
How is bile salt synthesis regulated and by what enzyme?
bile salts returning in enterohepatic circulation are rate-limiting and inhibited by 7alpha-hydroxylase
recirculation of bile salts to the liver stimulates biliary secretion
how are bile acids excreted?
facilitated diffusion from hepatocytes
how are bile salts absorbed from blood?
coupled to NaKATPase. BA/Na+ symporter.
How & where is hemoglobin broken down?
reticuloendothelial system. Then bilirubin is transported by albumin to liver.
In liver: bilirubin glucaronide (conjugated bilirubin) secreted into bile (yellow). In intestine bilirubin is unconjugated, converted to urobilinogen (by intestinal bacteria), then oxidized to urobilin and stercobilin (dark stool's color)
what gives urine a yellow/brown color?
urobilin (from urobilinogen of gut)
gallbladder removes what from bile?
NaCl & water
Most common type of gallstones
cholesterol stones, forms around nidus
10-20% of gall stones
pigment stones (unconjugated bilirubin)
gall bladder wall often damaged by bacteria & bile saturated by conjugated bilirubin