Figure 4.

Schematic diagram of the urea cycle, ammonia detoxification, and glutamine synthesis inside a hepatocyte. (A) Periportal hepatocytes receive blood with high oxygen supply and nutrition from the portal vein and hepatic artery. In these hepatocytes, the ammonia detoxification is represented by the synthesis of the urea. Perivenous hepatocytes, aligned near the central vein, are supplied with less nutrition and low oxygenated blood, the ammonia detoxification here is accompanied by glutamine synthesis. (B) Ammonia enters the hepatocytes urea cycle as carbamoyl phosphate, passes through four enzymatic reactions and at final stage urea excretes to the blood.