Hepatocytes (liver parenchymal cells) perform the liver's metabolic functions: Formation and excretion of bile as a component of bilirubin metabolism (see Overview of bilirubin metabolism) Regulation of carbohydrate homeostasis Lipid synthesis and secretion of plasma lipoproteins Control of cholesterol metabolism Formation of urea, serum albumin, clotting factors, enzymes, and numerous other proteins Metabolism or detoxification of drugs and other foreign substances Overview of liver structure At the cellular level, portal triads consist of adjacent and parallel terminal branches of bile ducts, portal veins, and hepatic arteries that border the hepatocytes.