The Hepatobiliary System
The liver is attached to the gall bladder. The liver secretes bile into the hepatic ducts. The bile then flows into the gall bladder 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
Because it is saturated in blood the liver is a reddish brown colour. Every two and 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:
- The largest amount of blood (about 75%) 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 spleen releases iron, which is taken from the destruction of red blood cells, for use by the liver
- The liver’s second blood supply comes via the hepatic artery which delivers highly oxygenated blood from the lungs. Once the liver has de-oxygenated 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 fissure called the Porta Hepatis, before dividing into branches to the right and left lobes of the liver.