The liver receives a quarter of its blood supply from the hepatic artery, which comes from the heart. The other three quarters of its blood supply comes from the portal vein, which drains the intestine.
Blood draining from the intestine is filled with digested food substances for the liver to process.
Blood leaves the liver through the hepatic vein. This blood is a mixture of blood from the hepatic artery and blood from the portal vein. The hepatic artery provides the only blood supply to certain parts of the liver, particularly the supporting tissue and the walls of the bile ducts. Narrowing or blockage of the artery or its branches can cause considerable damage to these areas. Flow through the artery may be disrupted by an injury, such as a gunshot wound or surgical trauma, or by a blood clot.