Liver

The liver is the largest gland in the body, weighing about 1,500 g, located in the right hypochondrium. It performs over 500 different functions and is the body's central biochemical laboratory.

Anatomical structure

The liver consists of the right (larger) and left lobes, separated by the falciform ligament. The quadrate and caudate lobes are also distinguished on the visceral surface. In surgical practice, segmental division is used - 8 segments according to Quinaud, each with its own blood supply and bile outflow.

Hepatic hilum is the area on the lower surface where the portal vein and hepatic artery enter and the bile ducts exit.

Microstructure: hepatic lobule

The functional unit of the liver is the hepatic lobule (there are about 500,000 of them). This is a hexagonal prism with a diameter of 1–2 mm, in the center of which runs the central vein. Hepatocytes (liver cells) are arranged radially, like the spokes of a wheel, with sinusoids flowing between them - special capillaries where arterial and portal blood mix.

In the walls of the sinusoids there are Kupffer cells - macrophages that filter bacteria and toxins from the blood coming from the intestines.

Dual blood supply

The liver is unique in that it receives blood from two sources:

• Portal vein (75% of blood flow) - carries blood from the intestines, rich in nutrients
• Hepatic artery (25%) - carries oxygenated blood

1.5 liters of blood per minute passes through the liver - a quarter of cardiac output.

Main functions

• Detoxification - metabolism of drugs, alcohol, ammonia
• Protein synthesis - albumin, coagulation factors, transport proteins
• Bile production - 500–1000 ml per day for emulsification of fats
• Storage - glycogen, vitamins A, D, B12, iron
• Regulation - levels of glucose, cholesterol, amino acids in the blood

Regeneration

The liver has a unique ability to regenerate. When up to 75% of the tissue is removed, it is able to restore the original volume in a few weeks. This property is the basis of living donor transplantation: part of the liver is transplanted into the recipient, and in both of them it grows back to normal size.

You can see the lobes, segments and vessels of the liver in volume in 3D anatomy atlas Humio - rotate the model, zoom in and study the topography of this unique organ.