Medical Health Encyclopedia

The Architecture. The liver is a built on a framework of lobes:

• The lobes. The liver is divided into two major lobes, a right and a smaller left, that are separated by tough, fibrous connective tissue.
• The lobules. The liver's two major lobes contain about 100,000 smaller lobes, called lobules. Each lobule contains microscopic columns of liver cells and blood vessels. Bracing the corners of each lobule column are an artery and a vein that carry blood and a bile duct that drains bile.
• The arteries and veins. The arteries bring oxygen-rich blood to nourish the liver cells. The veins supply the liver cells with blood containing the nutrients and toxins that the liver cells process. A central vein runs through each column and collects the processed blood from both sources. These veins join to form the hepatic vein.
• The bile ducts. The bile ducts in the column corners collect bile draining from tiny canals around the liver cells. These ducts eventually join to form the large common bile duct that leads from the liver to the gallbladder.

The Liver's Blood Supply

The liver is rich in blood. It holds about a pint, or 13% of the body's supply. It is furnished with blood from two large vessels, the hepatic artery and the portal vein, and is drained of blood by the hepatic vein. (The word "hepatic" derives from the Latin word for liver.)

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The hepatic artery. This artery supplies blood to the liver directly from the heart, and it is this blood that nourishes the liver.

The portal vein. The portal vein carries blood into the liver that has been circulating through the stomach, spleen, and intestine. This is the blood that the liver processes. The liver extracts nutrients and toxins from this blood.

The hepatic vein. This vein carries blood from the liver and connects to the inferior vena cava, a large vein that conducts blood back to the heart.