Illustration of the structure of a liver lobule. Oxygenated blood is supplied to the hepatocytes (liver cells) by the hepatic artery (red). The portal vein (blue, outer) carries blood that contains substances absorbed from the digestive system for processing by the hepatocytes. The hepatic artery and portal vein drain into the central vein (blue, centre), which in turn drains into the hepatic vein (not seen) and back into the general circulation. Bile is produced by hepatocytes and collected for transport to the gall bladder via the bile duct (yellow).