== Introduction ==

The liver functions as a vast biosynthetic chemical factory, synthesizing large complex molecules from substances brought to it in the blood, particularly substances recently absorbed by the intestine and transported by the portal blood system. All of the biochemical functions of the liver are carried out by the epithelial parenchymal cells of the liver, the hepatocytes. Hepatocytes are responsible for bile synthesis and secretion, excretion of bilirubin, protein carbohydrate and lipid metabolism, storage (vitamins A, D and B12 and iron as ferritin), and conjugation and elimination of metabolites and toxins.