Biliary Secretion and EH secretion Flashcards
What are the 3 roles of Bile?
1) Lipid digestion/absorption
2) Cholesterol Homeostasis
3) Excretion of lipid soluble xenobiotics/drug metabolites/heavy metals
Where are bile salts absorbed in the SI?
Jejunum
What emulsifies lipids?
Bile Salts
What do the end products of fat digestion along with bile salts and cholesterol form?
Mixed micelles
What is the function of mixed micelles?
Lipid transport systems
How much bile is produced by the liver daily?
500ml
What does CCK induce?
Release of bile, as gallbladder contracts
Were are bile salts reabsorbed?
Terminal Ileum
What circulation returns bile salts to the liver?
Enterohepatic
Where are gallstones found in obstructive jaundice?
CBD
When does bile production start?
Week 12
What is formation of bile dependent on?
Hepatic synthesis and canalicular secretion of bile acids
Why do Bile Acids stay intraluminal?
So they are more likely to be reabsorbed
What enzyme converts cholesterol into a primary bile acid?
Cholesterol 7 alpha hydroxylase
What does emulsification do for lipolysis?
Increases the surface area
Why are bile salts described as amphipathic?
(Both hydrophilic and hydrophobic parts)
Reduce surface tension and aid emulsification
What are the functions of bile acids? (6)
1) Induce bile flow and secretion of biliary lipids
2) Digestion of dietary fats
3) Facilitate protein absorption
4) Cholesterol homeostasis
5) Antimicrobial
6) Prevent calcium gallstones, and oxalate renal stones
Summarise bile formation and emulsification
1) Cholesterol bd by C8AH into Bile acids
2) Stored in Gallbladder and 10x conc
3) Makes fat into emulsion as micelles made and co-lipase work with lipase to break FA off TG into MG
4) Diffuse across enterocytes and reassembled as TG before excreted into lacteals as chylomicrons
5) Enter general circulation and BD by lipoprotein lipase on BV surface into FFA and MG
