Hepatobiliary System Flashcards
Identify the basis for the anatomic subdivision of the liver and the specifics of its blood supply
Anatomic divisions:
o Divided into right and left lobe
o Subdivided into 8 functional segments
Dual blood supply to liver
o Portal vein (~1300 ml/min)
o Hepatic artery (~500 ml/min)
o Result: infarcts are rare
Single blood supply to biliary tree
o Hepatic artery
o So with obstruction → necrosis and stricture formation (ischemic cholangitis)
o If bile escapes → biloma formation (bile accumulation in liver parenchyma outside of bile ducts) → infection → abscess formation within liver
Blood drainage:
o 3 hepatic veins (right, middle, left)
NOTE: Caudate lobe (segment 1) = functionally separate
• Has own venous drainage directly to vena cava; partly through middle hepatic vein
• Result: compensatory hypertrophy when hepatic outflow obstruction at level of main hepatic veins (“Budd-Chiari Syndrome”)
Identify the basis for the anatomic subdivision of the liver and the specifics of its blood supply
Anatomic divisions:
o Divided into right and left lobe
o Subdivided into 8 functional segments
Dual blood supply to liver
o Portal vein (~1300 ml/min)
o Hepatic artery (~500 ml/min)
o Result: infarcts are rare
Single blood supply to biliary tree
o Hepatic artery
o So with obstruction → necrosis and stricture formation (ischemic cholangitis)
o If bile escapes → biloma formation (bile accumulation in liver parenchyma outside of bile ducts) → infection → abscess formation within liver
Blood drainage:
o 3 hepatic veins (right, middle, left)
NOTE: Caudate lobe (segment 1) = functionally separate
• Has own venous drainage directly to vena cava; partly through middle hepatic vein
• Result: compensatory hypertrophy when hepatic outflow obstruction at level of main hepatic veins (“Budd-Chiari Syndrome”)
Identify the basis for the anatomic subdivision of the liver and the specifics of its blood supply
Anatomic divisions:
o Divided into right and left lobe
o Subdivided into 8 functional segments
Dual blood supply to liver
o Portal vein (~1300 ml/min)
o Hepatic artery (~500 ml/min)
o Result: infarcts are rare
Single blood supply to biliary tree
o Hepatic artery
o So with obstruction → necrosis and stricture formation (ischemic cholangitis)
o If bile escapes → biloma formation (bile accumulation in liver parenchyma outside of bile ducts) → infection → abscess formation within liver
Blood drainage:
o 3 hepatic veins (right, middle, left)
NOTE: Caudate lobe (segment 1) = functionally separate
• Has own venous drainage directly to vena cava; partly through middle hepatic vein
• Result: compensatory hypertrophy when hepatic outflow obstruction at level of main hepatic veins (“Budd-Chiari Syndrome”)
Compare and contrast the morpho-functional unit of the liver and the distinction between the liver lobule and the portal acinus.
Portal acinus
o Smallest functional unit
o Cluster of hepatocytes supplied by terminal portal vein → through liver sinusoids → collected in terminal hepatic venule
Hepatocytes in acinus occupy 3 zones:
• Zone 1: closest to terminal portal vein, receive highest O2 and nutrient concentration
• Zone 2: between 1 & 3
• Zone 3: closest to the terminal hepatic vein; exposed to lowest O2 concentration and most susceptible to hypoxic injury
Hepatic lobule
o Morphological liver lobule
o Cluster of hepatocytes centered by central vein (terminal hepatic venule)
Space of Disse
o Space between sinusoid and hepatocytes; contains Stellate cells
o No true basement membrane
Endothelial Cells in the liver
- Form the sinusoids
- Have fenestrae = regulation of traffic of macromolecules
- Pathologic states (alcoholic liver disease = fenestrae get shut off)
- No true basement membrane
Kupffer cells
- 90% of tissue-bound macrophages in body
- Located in sinusoids
- Clear portal blood of endotoxins from gut; general defense and clearance of bacteremia
- With cirrhosis = less blood flow to liver → Kupffer cells can work on pathogens → more prone to infection
Stellate cells (Ito or lipocytes)
- Storage of vitamin A
- Activation = lose vitamin A and become myofibroblasts
Able to:
• Contract → obliterate sinusoid → portal HT
• Secrete collagen = deposited in space of Disse → barrier formation; impair blood flow
Pit Cells
- Large granular lymphocytes with natural killer ability
- Located in sinusoids
- Hyperplasia → hepatomegaly and liver dysfunction
Compare the drainage of the lymph (lymphatic system) and of the bile (biliary tree) from the liver.
Bile canaliculi
Created by plasma membrane domains of 2 adjacent hepatocytes
• From apical membrane of other epithelial cells
Drain into bile ducts (in portal triad) → ductules (“Canals of Hering”)
• Ductule cells = stem cells of liver
Lymph
o Formed in space of Disse
o Drains into space of Mall (in periphery of portal triad between limiting plate and CT in portal space)
o Drains into lymphatic vessels → cysterna chhyli
Contrast apoptosis vs. necrosis
Apoptosis o Cell shrinkage o Endonucleases cleave DNA o Fragmentation → small condensed bodies with intact organelles (apoptotic bodies) o No inflammation
Necrosis o Cell swelling o Formation of plasma membrane blebs → rupture (cytolysis) o Rupture and release of cell organelles o Non-specific DNA hydrolysis
Identify the two main mechanisms of new hepatocyte formation in liver regeneration.
Compensatory hyperplasia
o Decrease in hepatocyte mass (up to 70%) → stimulates hepatocyte division
o Chronic liver disease: fibrous tissue may be deposited = distorts liver architecture → cirrhosis (fibrosis encircles regenerative nodules destroying acinar architecture)
Stem cell regeneration
o Sudden diffuse hepatocyte necrosis (ex: acute liver failure) → division and differentiation of cells in Canal of Hering (stem cells forming the ductule)
o Potential of becoming bile duct cells and hepatocytes
o Process takes months to occur (so may still need a transplant)
Compare and contrast the morpho-functional unit of the liver and the distinction between the liver lobule and the portal acinus.
Portal acinus
o Smallest functional unit
o Cluster of hepatocytes supplied by terminal portal vein → through liver sinusoids → collected in terminal hepatic venule
Hepatocytes in acinus occupy 3 zones:
• Zone 1: closest to terminal portal vein, receive highest O2 and nutrient concentration
• Zone 2: between 1 & 3
• Zone 3: closest to the terminal hepatic vein; exposed to lowest O2 concentration and most susceptible to hypoxic injury
Hepatic lobule
o Morphological liver lobule
o Cluster of hepatocytes centered by central vein (terminal hepatic venule)
Space of Disse
o Space between sinusoid and hepatocytes; contains Stellate cells
o No true basement membrane
Endothelial Cells in the liver
- Form the sinusoids
- Have fenestrae = regulation of traffic of macromolecules
- Pathologic states (alcoholic liver disease = fenestrae get shut off)
- No true basement membrane
