The liver receives the oxygen and nutrients it needs in blood that comes from two large blood vessels. The portal vein, provides about two thirds of the blood. This blood contains oxygen and many nutrients brought to the liver from the intestine for processing. The other, the hepatic artery, provides the remaining one third of blood. This oxygen-rich blood comes from the heart and provides the liver with about half of its oxygen supply. Receiving blood from two blood vessels helps protect the liver: If one of these blood vessels is damaged, the liver can often continue to function because it receives oxygen and nutrients from the other blood supply.

Did You Know... Unlike the rest of the body, the liver is the only organ in the body that gets most of its oxygen supply from a vein.

Blood Supply of the Liver

Blood leaves the liver through the hepatic veins. This blood is a mixture of blood from the hepatic artery and from the portal vein. The hepatic veins carry blood to the inferior vena cava—the largest vein in the body—which then carries blood from the abdomen and lower extremities to the right side of the heart.

Blood vessel (vascular) disorders of the liver usually result from inadequate blood flow.

• If blood flow (and thus oxygen supply) to the liver is inadequate, ischemia results.
• If blood flow out of the liver is inadequate, blood backs up in the liver, causing congestion.

For example, in heart failure, blood flow to (pump failure) and from the liver (congestion) is inadequate. Both can result in ischemia. In people with blood clotting disorders, blood flow to the liver through the obstructed portal vein or from the liver through the hepatic veins may be slowed or blocked.

Last full review/revision December 2007 by Eldon A. Shaffer, MD