The Circulatory Routes of the Liver

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The liver is unique among organs in that it receives blood via two distinct circulatory routes: systemic circulation and hepatic portal circulation. Each of these routes provides blood of differing compositions that allow the liver to perform its unique and vital digestive and metabolic functions.

Oxygenated blood leaving the heart first passes through the aorta, which descends from the thorax into the abdomen as the abdominal aorta. The celiac trunk branches from the abdominal aorta and splits into three major branches, one of which, the common hepatic artery, supplies blood to the liver and gallbladder along with the stomach, small intestine, and pancreas. The common hepatic artery further divides into three more branches, with the proper hepatic artery supplying blood to the liver, gallbladder, and part of the stomach. The common hepatic artery further bifurcates into the left and right hepatic arteries to deliver blood the left and right sides of the liver. As the right hepatic artery approaches the gallbladder, it branches off to form the cystic artery, which supplies the gallbladder and cystic duct with oxygenated blood. These arteries further branch off into many smaller arteries and arterioles and, finally, capillaries to provide oxygen and nutrients to all of the tissues of the liver and gallbladder.

The hepatic portal vein provides the liver's tissues with deoxygenated blood that has passed through the tissues of the stomach, pancreas, spleen, and intestines. This blood is rich in dissolved nutrients absorbed from digested food, as well as any toxins or medications consumed by the body. Before this material can reach the other tissues of the body, it passes through the hepatic portal vein and enters the liver, wherein it is divided among many specialized capillaries, known as sinusoids. In the sinusoid, the deoxygenated blood is processed by hepatocytes, which can absorb or release nutrients as needed and metabolize dangerous chemicals before they can affect the rest of the body.