Bile Secretion and Gallbladder Function Flashcards
Bile acids synthesized from what? Where
Cholesterol, Liver
CCK stimulates what in the gallbladder
Contraction and relaxation of the sphincter of oddi
2 primary bile acids are
Cholic acid and Chenodeoxycholic acid (these are the only 2 bile acids synthesized by the liver.
About 40 % of bile salts are reabsorbed passively,
55% actively reabsorbed
The remianing 5% lost in the stool
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Whats the difference between a bile acid and a bile salt?
Bile acids are what is originally secreted. They are not very water soluble and have a pka around7. Bile acids are modified by bacteria in the intestines and then conjugated to an amino acid (either glycine or taurine) in order to make them more water soluble
KNOW…Which bile acid is most likely to be reabsorbed?
The one that is the most lipophilic
The one that has no Hydroxyl groups and no conjugated amino acid.
Bile acids/salts form micelles which are made up of?
Bile acid/salt, phospholipids, and cholesterol…
All of these things need to exist in a constant proportion called critical micellar concentration. ANytime this is changed you get bile acids an dbile salts precipitating and forming gallstones
What are the products of fat digestion
Free fatty acids and monoglycerides
What do micelles do to FFAs and Monoglycerides?
Solubilize them
Micelles also solubilize fat soluble vitamins
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Reabsorption of Bile acids into hepatocytes is powered by
Na/K ATPase
Once Billirubin is formed by the breakdown of hemoglobin in the RES, it travels in the bloodstream bound to?
Plasma Albumin
Billirubin is made water soluble in the liver by conjugating it to Billirubin Glucuronide
KNOW….realize that this means billirubin is not incorporated in micelles because micelles only contain fat soluble stuff.
Humans contain no CCK receptors, therefore CCK operates through
Vagal Vagal reflex
