What is the blood supply of the liver?

The liver is unique in that it has a dual blood supply, both the portal venous system and the systemic circulation. 75% of the blood that flows through the liver is from the portal venous system, venous blood (deoxygenated) that has drained from the organs of the GI tract. This blood has no oxygen in it but it very rich in nutrients absorbed from the gut. The other 25% of the blood that flows through the liver is arterial blood (oxygenated) that has branched off the aorta, the main artery exiting the heart. This blood is very rich in oxygen from the lungs, but has no nutrients. The 'hepatic artery proper' is the name of the artery that supplies oxygenated blood to the liver.