Chapter 18 – Liver and Biliary Tract Flashcards
What is the normal live weight?
The normal adult liver weighs 1400 to 1600 gm, constituting approximately 2.5% of body weight.
What is the blood supply of the liver?
The liver has a dual blood supply:
- the portal vein provides 60% to 70% of hepatic blood flow,
- and the hepatic artery supplies 30% to 40%.
What is the porta hepatis?
The portal vein and the hepatic artery enter the
- *liver through the hilum,** also called porta hepatis, which is a transverse fissure in the inferior
- *surface of the liver**.
Within the liver, the branches of the portal veins, hepatic arteries, and bile ducts travel in parallel in portal tracts, ramifying variably through 17 to 20 orders of branches
erminology of the hepatic microarchitecture is based on two different concepts:
- T the hepatic lobule and
- the hepatic acinus.
What does the lobal model of the liver says?
According to the lobular model, the liver is divided into 1- to 2-
mm diameter hexagonal lobules oriented around the terminal tributaries of the hepatic vein
(terminal hepatic veins) , with portal tracts at the periphery of the lobule.
The hepatocytes in the
vicinity of the terminal hepatic vein are called “centrilobular”; those near the portal tract are
“periportal” ( Fig. 18-1 ).
What does the acinar model of the liver says?
In the acinar model the hepatocytes near the terminal hepatic veins are the distal apices of roughly triangular acini, whose bases are formed by the penetrating septal venules from the portal vein extending out from the portal tracts. [1]
In the acinus the
parenchyma is divided into three zones,
- zone 1 being closest to the vascular supply,
- zone 3 abutting the terminal hepatic venule and most remote from the afferent blood supply, and
- zone 2 being intermediate.
In the acinar model of the liver acinus the
parenchyma is divided into three zones,
Which zone is closest to the ,vascular supply?
zone 1 being closest to the vascular supply,
No 1 gets the most nutrients! Kaya number 1 in class!
In the acinar model of the liver acinus the
parenchyma is divided into three zones,
Which zone most remote from the afferent blood supply?
zone 3
Third place always last! Last kahit sa nutrients!
Regardless of the model used, zonation of the parenchyma is an important concept for what reason?
because of the gradient of activity displayed by many hepatic enzymes, and the zonal distribution of certain types of hepatic injury.
While the acinar model best describes
the physiologic relationships between hepatocytes and their vascular supply, the histopathology
of the liver is usually discussed on the basis of a lobular architecture.
Histopathology of the liver is usually discussed on the basis of what?
lobular architecture.
FIGURE 18-1 Microscopic anatomy of the liver;
the two models, hepatic lobular model and
acinar model, are illustrated. In the lobular model the terminal hepatic vein (CV) is at the center of a “lobule,” while the portal tracts (PV) are at the periphery.
Pathologists refer to the
regions of the parenchyma as “periportal and centrilobular.” In the acinar model, on the basis
of blood flow, three zones can be defined, zone 1 being the closest to the blood supply and
zone 3 being the farthest. BD, bile duct; HA, hepatic artery.
How are the hepatocytes organized?
- Hepatocytes are organized into cribriform, anastomosing sheets or “plates” extending from portal tracts to the terminal hepatic veins.
- Between the plates of hepatocytes are vascular sinusoids.
- Blood traverses the sinusoids and exits into the terminal hepatic veins through numerous orifices in the vein wall.
- Hepatocytes are thus bathed on two sides by well-mixed portal venous and hepatic arterial blood, making hepatocytes among the most richly perfused cells in the body.
- The sinusoids are lined by fenestrated and discontinuous endothelial cells.
- Deep to the endothelial cells lies the space of Disse, into which protrude abundant microvilli of hepatocytes.
- Scattered Kupffer cells of the mononuclear phagocyte system are attached to the luminal face of endothelial cells, and fat-containing hepatic stellate cells (HSCs) are found in the space of Disse.
- Between abutting hepatocytes are bile canaliculi, which are channels 1 to 2 μm in diameter, formed by grooves in the plasma membranes of facing hepatocytes and separated from the vascular space by tight junctions. These channels drain into the canals of Hering, ductular structures that connect the bile canaliculi to bile ductules in the periportalregion.
- The ductules empty into the terminal bile ducts within the portal tracts. [2]
- The liver also contains lymphocytes, including relatively large numbers of natural killer cells, and NK-T cells (
- Chapter 6 ).
What is in between the plates of the hepatocytes?
vascular sinusoids.
Blood traverses the sinusoids and exits into the terminal hepatic veins through numerous orifices in the vein wall.
Hepatocytes are thus bathed on two sides by well-mixed portal venous and hepatic arterial blood, making hepatocytes among the most richly perfused cells in the body.
What lines the sinusoids?
The sinusoids are lined by fenestrated and discontinuous endothelial cells.
What lies deep to the endothelial cells?
the space of Disse, into which protrude abundant microvilli of hepatocytes.
Scattered Kupffer cells of the mononuclear phagocyte system are attached to the luminal face of endothelial cells, and fat-containing hepatic stellate cells (HSCs) are found in the space of Disse.
