54-55 Liver Flashcards
The majority of the liver’s blood supply comes from the _____________, and the rest comes from the _____________ (a branch of the _____________).
- Portal v.
- Hepatic a. (branch of the celiac a.)
What are the 3 major, general functions of the liver?
- Metabolism
- Detoxification
- Excretion
What is the major cell type of the liver?
Hepatocytes
Generally, how are hepatocytes arranged amongst themselves?
They are arranged in anastomosing cords that form plates.
By what small vessel do plates of hepatocytes receive blood?
Is this low or high resistance?
Sinusoids (smaller branches of portal v. and hepatic a.)
- Low resistance
What vessel drains blood out of the liver?
Central v. (of hepatic v.)
What 3 vessels are part of the hepatic triad?
- Hepatic a.
- Portal v.
- Bile duct
*Explain where the cells of the 3 functional “zones” of a liver lobule are.
- Zone 1: hepatocytes closest to triad (therefore have largest supply of nutrients and O2)
- Zone 2 - intermediate between zones 1 and 3.
- Zone 3: closest to the hepatic/central vein
- What’s another name for zone 1 cells?
- What’s another name for zone 3 cells?
- Periportal cells (near the portal v.)
- Pericentral cells (near the central v.)
- Which of the 3 zone’s cells are most susceptible to oxidative injury?
- Which are most active in detox?
- Which are most active in bile synthesis?
- Which are most sensitive to ischemia?
- Zone 1 cells
- Zone 1 cells
- Zone 3 cells
- Zone 3 cells
What can happen to the 3 hepatic cell zones during liver dz?
Cells in zones 2 and 3 can function as zone 1 cells (blood backed up, spills out?)
Which hepatic cell type is the origination point of the biliary system?
Hepatocytes
Where are bile canaliculi formed w/r/t hepatocytes?
What larger vessel does the formed bile drain into?
B/w the hepatocytes
- Bile goes from canaliculi to biliary ductules
What's the name of the cells that line the biliary ductules? *What class of epithelial cells are they?
Cholangiocytes
- Simple columnar epithelial cells
In a liver lobule, hepatocytes closest to the bile duct are farthest from the _______________.
Central v.
In what duct can bile flow bidirectionally?
What is the name of the bile duct coming from the liver before and after this duct branches off of it?
Cystic duct (to GB)
- Before: common hepatic duct
- After: CBD
Name all of the ducts that bile flows from, starting at the hepatocyte.
- Bile canaliculi (b/w cells)
- Biliary ductules
- Bile ducts
- R + L hepatic ducts
- Common hepatic duct
(5. 5- Cystic duct) - CBD
(6. 5 Common pancreatic duct comes in before Sphincter of Oddi)
Which of the following do hepatocytes participate in the metabolism of?
Carbs, ptns, lipids
All 3
*What 2 major processes does the liver play a part in w/r/t carbohydrate homeostasis?
- GNG (conversion of other sugars to glc)
2. Glucose buffer fcn (stores glycogen)
How would blood sugar levels before and after meals be altered w/impaired liver function?
Hyperglycemia during/after meals and hypoglycemia between meals.
*What 3 major processes does the liver play a part in w/r/t lipid homeostasis?
- Hepatocytes are a rich store of enzymes for FA oxidation (contributes to energy generation)
- Convert products of carb metabolism into lipids: synthesis of lipoproteins, cholesterol and phospholipids.
- Convert cholesterol to bile acids.
*What 3 major processes does the liver play a part in w/r/t protein homeostasis?
- Synthesizes all of the non-essential AAs; also modifies AAs so they can enter pws for carb synthesis.
- Synthesizes almost all plasma ptns, including albumin (determines plasma oncotic pressure) and the clotting factors.
- Converts ammonia to urea (excreted in urine)
How could liver failure lead to problems w/blood oncotic pressure?
Major symptom?
- Hypoalbuminemia (can’t make enough)
- Sx: Peripheral edema due to low plasma oncotic P (lack of clotting factors as well)
What general types of materials does the liver detox?
How many times do they pass thru the blood before being detoxed?
- Endogenous or exogenous toxic molecules (including pharmaceutical drugs); bacterial toxins
- Modifies them in “first pass metabolism” so little/none can enter systemic circulation
Describe the phases of “first-pass metabolism” during detoxification.
(what types of enzymes catalyze phase I rxns?)
1) Phase I reactions – oxidation, hydroxylation etc. – catalyzed by cytochrome P-450 enzymes.
2) Phase II reactions – conjugate the substances with glucuronide, sulfate, amino acids or glutathione.
What happens to the products of “first pass metabolism” after they’re processed (for detox)?
The products are excreted in feces (via bile) or in urine (via kidney).
*Are water-soluble catabolites excreted in the feces or the urine? What is the exception?
Urine, unless they are large, in which case they are excreted in the feces via bile.