The liver is the second largest organ and the largest gland of the human body. It lies on the right of the stomach and makes a kind of bed for the gallbladder. Liver is also one of the few human internal organs that are capable of natural regeneration of lost tissue. 25% of the remaining liver can regenerate into a whole liver again.
The functions of liver in human body include metabolism, glycogen and several other substances storage, plasma protein synthesis, and drug detoxification. In lipid metabolism, the liver produces and excretes bile, a liquid required for emulsifying fats. It synthesizes cholesterol and produces triglycerides (fats). The liver also synthesizes glucose from certain amino acids, lactate or glycerol, forms glycogen from glucose and vice versa, breaks down isulin and other hormones. In a process known as drug metabolism, the liver breaks down most medicinal products and toxic substances. In addition, it stores substances such as glucose in the form of glycogen, vitamin B12, iron and copper. Those functions are carried out by the liver cells called hepatocytes which make up 70-80% mass of the liver.
Because of its complex functions, the liver cannot be replaced (yet) by any artificial organ or device. The only way to replace the liver is liver transplant. However, some of the functions, especially detoxification, of the liver can be emulated by liver dyalisis, a experimental treatment for liver failure. The treatment employs artificial filtration and absorption devices.