Final answer:
The liver is divided into eight segments according to the Couinaud classification system, with each having its own vascular and biliary supply. This system is based on the distribution of the hepatic and portal veins.
Step-by-step explanation:
The Couinaud classification divides the liver into eight functionally independent segments, each with its own vascular inflow, outflow, and biliary drainage. In this system, the segments are numbered from one to eight. Typically, segments are arranged in a clockwise fashion when viewed from below (the inferior aspect), with segment I being the caudate lobe and segments II through VIII corresponding to areas in both the right and left lobes of the liver. The division of these segments relies heavily on the hepatic vein and portal vein distribution within the liver.
The liver, which is the largest internal organ and the largest gland in the human body, performs a range of essential functions, such as detoxification, synthesis of plasma proteins, and production of bile. It receives oxygenated blood from the hepatic artery and nutrient-rich blood from the gastrointestinal tract via the hepatic portal vein. Inside each of the liver's lobules, metabolic cells known as hepatocytes are arranged in plates radiating outward from a central vein. The hepatic sinusoids are specialized blood capillaries that receive blood from the hepatic portal vein and the branches of the hepatic artery.