Hepatic 2 Flashcards
Basolateral aspect of hepatocytes
faces Space of Disse
Apical aspect of hepatocytes
faces canniculi lumen
What molecules can be reabsorbed from the bile with Na+ transport?
adenosine and AAs
Are transporters in the apical membrae unidirectional?
yes (mostly)
icterus
jaundice
hyperbilirubinemia
excess bilirubin in blood serum
Jaundice
yellowing of the skin and/or whites of the eyes, d/t excess bilirubin
3 Possible Causes of Jaundice
- Obstruction of the Bile Duct
- Liver Disease
- Excessive breakdown of RBCs
How can the liver get rid of RBCs?
Kupffer cells will phagocytose the dying RBCs and breakdown into hemoglobin, then into heme and globin
3 Major Organs that can breakdown RBCs
- Liver
- Spleen
- Bone Marrow
What is globin broken down into?
amino acids
What happens to the heme of old RBCs?
the iron component of heme can be used by the bone marrow; can also be broken down to bile and go to the gallbladder
How does heme become bile?
Heme goes through a redox rxn to become bilirubiin, which is then secreted to the blood where it binds to albumin, then hepatocytes pick up the complex, albumin removed, conjugated by UGT, and goes to gallbladder as bile
What makes shells and bird poop green?
biliverdin
urobilinogen
when bacteria metabolize bilirubin in the intestine
3 Pathways of Urobilinogen
- 20% reabsorbed by intestine and into the portal vein
- 20% excreted via the kidneys
- 60% metabolized into stercobilin
What gives urine its yellow color?
urobilin, the oxidized form of urobilinogen when exposed to air
What component makes feces brown?
stercobilin
3 Types of Hyperbilirubinemia
- Pre-hepatic
- Hepatic
- Post-hepatic
Pre-Hepatic Hyperbilirubinemia
increased RBC destruction –> lots of heme –> lots of circulating bilirubin
Which types of hyperbilirubinemia would have high unconjugated bilirubin levels in the blood?
pre-hepatic and hepatic
Which types of hyperbilirubinemia would have high levels of conjugate bilirubin in the blood?
post-hepatic
Hepatic Hyperbilirubinemia
hepatic dysfunction/damage affects liver’s ability to transform the bilirubin so it will “back up” in the blood serum
Post-Hepatic Hyperbilirubinemia
blockage of biliary outflow; conjugated bilirubin goes back into systemic ciculation
Cholestasis
blockage of biliary outflow
Cholelilthiasis
gallstones
Which type of hyperbilirubinemia results in dark-colored urine?
post-hepatic (conjugated is more polar so can go through the kidney)
Diagnostics to differentiate between pre-hepatic and hepatic?
Pre-hepatic will have dec. RBCs
Hepatic will have inc. AST, inc. ALT, and dec. albumin
2 Major Functions of Bile
- Bile is the excretory route for solutes that can’t be excreted by the kidney
- Needed to form micelles for lipid digestion and absorption
Constituents of Bile
bile acids/salts, phospholipids, cholesterol, IgA,bile pigments, water, inorganic salts, mucus
Which constitueents of bile are amphipathic?
bile acids, bile salts, and phopholipids
IgA in bile
inhibits bacterial growth within the bile
Bile Acids vs. Bile Salts
Bile Acids are protonated, neutral, not [very] water soluble
Bile Salts are deproteonated, negatively charged, more water soluble
Which is more water soluble - bile acid or salt?
bile salts
Why are bile salts negatively charged?
d/t conjugation with sulfate or glucuronate (or glycine or taurine)
Only cell type that can synthesize bile acids?
hepatocytes
Primary Bile Acids
synthesized in hepatocytes
Secondary Bile Acids
synthesized in intestine by bacteria that dehydroxylates the primaries
Do hepatocyte secretions have more bile salts or bile acids?
bile salts
How are secondary bile acids reabsorbed in the gut?
enterohepatic recirculation
Enterohepatic circulation
95% of bile acids and salts are absorbed in ileum and colon (some throughout entire GI but these are main locations) and enter portal venous system
Cholangiocytes
name of biliary epithelial cells
3 Ways Bile Secretion is Controlled
- Positive feedback - increase secretion of bile salts
- Negative feedback - decrease synthesis of bile salts
- CCK - secreted by intestine after a meal and inc. release of bile acid from gallbladder
