Liver Physiology (Johnson/Costanzo) Flashcards
What causes ascites with liver failure?
liver responsible for protein synthesis; in failure, decr oncotic pressure = ascites
Cholesterol is used the synthesize:
bile acid
Secretin stimulates:
secretion of bicarb and water into the ducts
In gallbladder, bile concentrated via:
active absorption of Na, Cl, bicarb, water
What are the functions of CCK? What do these cause?
contraction of the gallbladder
relaxation of the sphincter of Oddi
**causes stored bile to flow from the gallbladder into the lumen of the duodenum
How does the timing of GB contractions relate to duodenal contractions?
they coincide
The hepatocytes of the liver (intermittently/continuously) synthesize and secrete the constituents of bile.
continuously
The components of bile are:
the bile salts, cholesterol, phospholipids, bile pigments, ions, and water.
What is the function of the GB?
- store bile
- concentrate bile salts (by absorption of water and ions)
- eject bile (~30min after meal)
What signals the secretion of CCK?
chyme reaching the small intestine
In the small intestine, the bile salts function in:
emulsifying and solubilizing dietary lipids
What happens to bile salts once they’ve done their business?
When lipid absorption is complete, bile salts are recirculated to liver via enterohepatic circulation
(where they are actively extracted from portal blood)
How are bile acids reabsorbed?
40% of bile acids/salts are reabsorbed via passive diffusion
55% of bile acid/salts are actively reabsorbed in the ilium (contains specific receptors for bile acids/salts, Na dependent process)
Decreased reabsorption of bile acids results in:
increased bile acid synthesis
Bile acids returning from circulation inhibit:
bile acid synthesis via 7-beta-hydroxylase inh
(negative feedback)
**The liver must replace only the small percentage of the bile salt pool that is excreted in feces
Two primary bile acids (synthesized by liver):
What happens to primary bile acids once secreted into lumen of intestines?
Cholic acid
Chenodeoxycholic acid
portion of each is dehydroxylated by intestinal bacteria to produce 2 secondary bile acids
4 Bile acids, in order of greatest relative amount to least:
Cholic acid > chenodeoxycholic acid > deoxycholic acid > lithocholic acid
How does conjugation of bile acids in the liver change them?
conjugation to amino acids changes the pKas of bile acids and causes them to become much more water soluble
**there’s an additional explanation of this in the text that’s good
A “bile salt” is a…
bile acid conjugated with an amino acid
The most likely bile acid to be reabsorbed is the one that is the most _____
lipophilic
The critical property of bile salts is that they are ____.
Why is this significant?
amphipathic
allows them to form micelles and forms lipid droplets that repel, which increases surface area for digestion
A change in the critical micellar concentration leads to:
precipitation of gallstone
Micelles solubilize:
the products of fat digestion
fat soluble vitamins (which is why decr bile acids»_space; vit deficiency)
Micelles are comprised of:
4 different bile salts
phospholipids
cholesterol
