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20 Cards in this Set
- Front
- Back
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What are the functions of the liver?`-
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Intermediary metabolism of carbs, fats, proteins
Synthesis and secretion of plasma proteins (lipoproteins, albumin, clotting factors) Production and secretion of bile Alcohol metabolism, detox. of drugs/chemicals, as well as their activation Immune function and generation of inflammatory cytokines Storage of glycogen + vitamin A |
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What is the portal triad?
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Portal vein, hepatic artery, bile duct
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Describe the blood supply to the liver
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75% = deoxygenated nutrient rich blood from Portal vein --> venules
25% = oxygenated blood from hepatic arteries --> arterioles arterioles, venules --> sinusoids --> central veins --> sublobular veins --> hepatic veins |
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What are the cell types in the liver?
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Parenchymal cells: Hepatocytes (80%)
Nonparenchymal cells: -endothelial cells -hepatic stellate cells -Kupffer cells Biliary epithelial cells: line bile ducts and bile ductules |
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What is the normal ratio of portal veins to bile ducts in the portal triad?
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PV/BD = 8:1
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What separates the portal tract from the liver parenchyma?
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The limiting plate
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What lines the sinusoids of the liver?
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Fenestrated endothelium - blood cells cannot pass through these fenestrations, but, small particles can pass through to and from the hepatocyte.
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What do hepatic stellate cells do? How to demonstrate them histologically?
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aka "fat storing cells"; Reside in the space of Disse; contain lipid droplets for vitamin A storage; produce EXM. Use immunohistochemical staining against alpha-smooth muscle actin.
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What do Kupffer cells do?
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Liver macrophages of the monocyte-macrophage system. They phagocytize bacteria in the portal blood. The are Antigen Presenting Cells. They generate Inflammatory cytokines (TNF-α, TGF-β), and produce ROS: H2O2
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Describe the hierarchy of the biliary system in the liver
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Bile canaliculi -> canals of Hering -> bile ductules -> R, L hepatic ducts -> common hepatic duct -> common bile duct -> Duodenum
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What is a bile canaliculus?
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The bile canaliculus is a space formed by two apposing hepatocytes. Note: microvilli, functional complex that seals the canaliculus lumen from the intercellular space.
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How to stain for bile canaliculi?
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Bile secretion is an energy-dependent process: stain for ATPase
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What is the structural organization of the liver?
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1. The classic liver lobule as a structural and functional unit
2. The hepatic acinus as a functional unit |
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Describe the structural organization of a liver lobule
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Each lobe is roughly hexagonal around a central vein. Base on the direction of blood flow, the classic liver lobule is divided into 3 zones: perilobular, mid and centrilobular.
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Describe the properties of the blood received by the perilobular and centrilobular hepatocytes.
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The hepatocytes in the perilobular zone are first to be exposed to blood rich in O2, nutrients, and metabolites form the gut. The hepatocytes in the centrilobular area will receive blood low in oxygen, and nutrients as well as blood that has been altered by cells in the perilobular zone.
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Describe the metabolic activities of perilobular hepatocytes
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Increase glycogen storage, plasma protein production, Krebs cycle enzymes, and bile acid synthesis. They are resistant to injury and have a higher regenerative capacity.
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Describe the metabolic activities of centrilobular hepatocytes
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Increase in alcohol metabolism, fat deposition, drug detox/activation. Susceptible to injury, possess lower regenerative capacity
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Describe the organization of the liver acinus
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Divided into 3 zones: zone 1 closest to vasculature, zone 3 closest to central vein.
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What happens to the SER of hepatocytes upon phenobarbital treatment or alcohol consumption?
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SER proliferates in association with an induction of cytochrome P450 enzymes.
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What is the mechanism of liver fibrosis caused by alcohol consumption?
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Alcohol --> activates Kupffer cells --> increased production of transforming growth-factor beta, ROS species, free radicals --> activates Hepatic stellate cells --> increase Collagen I production
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