How the liver works

The Hepatobiliary System

The liver is attached to the gallbladder. It secretes bile into the hepatic ducts. The bile then flows into the gallbladder to be stored before draining into the duodenum during digestion. The liver, gallbladder and hepatic ducts are collectively known as the hepatobiliary system.

The pancreas also secretes digestive juices into the duodenum and is sometimes considered a subsidiary part of the hepatobiliary system.

The liver’s blood supplies

The liver is a reddish brown colour because it is saturated in blood. Every two and a half minutes a gallon of blood passes through the liver’s complicated network of arteries, veins and capillaries.

Unlike any other organ in the body, the liver has two blood supplies:

  • 75% of its blood comes in through the portal vein system. This is a network of blood vessels which transport blood through the intestine, stomach, the spleen and the pancreas, draining into the portal vein and then into the liver. All the products of digestion from nutrients to toxins pass into the liver via this route.
  • The liver’s second blood supply comes via the hepatic artery which delivers highly oxygenated blood from the lungs. Once the liver has deoxygenated and processed this blood, it is transported to the liver’s central hepatic vein. It then leaves the liver and travels up to the heart.

The portal vein and hepatic artery enter the liver through a through a fissure called the Porta Hepatis, before dividing to the right and left lobes of the liver.

How the liver is held together

The sinusoids, lymph vessels and bile ducts are supported by connective tissue. This tissue branches out and extends throughout the liver. The tissue provides the scaffolding through which these various channels and ducts are threaded.