Normal liver structure and blood supply

The liver is one of the heaviest organs in the body,weighing 1.2-1.5kg.It is classically divided into left and right lobes by the falciform ligament,but a more useful functional division is into the right and left hemilivers, based on the hepatic blood supply the right and left hemilivers are further divided into a total of eight segments in accordance with subdivisions of the hepatic and portal veins.Each segment has its own branch of the hepatic artery and biliary tree,and this segmental classification is used clinically to describe the position of liver tum ours on radiological imaging.A liver segment is made up of smaller units known as lobules,comprised of a central vein, radiating sinusoid separated from each other by single liver cell (hepatocyte)plates,and peripheral portal tracts.The functional unit of the liver is the hepatic acinus.
Blood flows into the hepatic acinus via a single branch of the portal vein and hepatic artery situated centrally in the portal tracts.The blood flows outwards along the hepatic sinusoids into one of several tributaries of the hepatic vein at the periphery o the acinus.Bile flows in the opposite direction from the periphery of the acinus through channels termed cholangioles,which converge in interlobular bile ducts in the portal tracts.The hepatocytes in each acinus lie in three zones,depending on their position relative to the portal tract. The hepatocytes  in zone 1 are closest to the terminal branchesof the portal vein and hepatic artery and are richly supplied with  oxygenated blood,and blood containing the hughest concentration of nutrients and toxins. Conversely,hepatocytes in zone 3 are furthest from the portal tracts and closest to the hepatic veins,and are therefore relatively hypoxic and exposed to lower concentrations of nutrients and toxins comparted with the zone 1 hepatoctes.