The liver is a unique organ because of its role in the body's processes of digestion, metabolism, toxin filtration and blood clotting. Because it has so many responsibilities, the liver is a robust organ and able to heal and regenerate if injured (which is especially important if it is damaged by the very toxins it helps filter out). The liver interacts with the rest of the body via the bile ducts and its blood supply, which consists of the hepatic artery and the portal vein.
Digestion and Metabolism
One of the liver's main duties is to interact with the digestive system. It does this in two different ways. First, the liver makes a compound called bile. Bile is needed in order for the body to absorb fats and oils from the diet. Oil-based substances do not mix well with the liquids in the rest of the digestive system because these liquids are mostly water (that is, oil and water don't mix). Bile acts as a sort of bridge between the oils and the water, which allows the oils (also known as lipids) to be absorbed by the intestines. Second, the liver is important in maintaining blood glucose levels. The liver takes sugar from the blood and stores it in the form of a carbohydrate called glycogen. As a result, the liver can pull sugar out of the blood when blood sugar levels are high and can replenish blood sugar by breaking down glycogen when blood sugar is low.
Toxin Filtration
Another function of the liver is to help rid the body of toxins. Toxins may be produced by the body itself (sometimes because cells have used up energy or because cells have died), or may come from an outside source (e.g, when a harmful substance has been consumed). In either case, the liver is in charge of filtering the blood and helping eliminate any chemicals that could be poisonous to the body. It does this by chemically changing toxins in the blood so they can dissolve more easily in water and be excreted through the urine. One of the main mechanisms involves a series of proteins called the cytochrome P450 system, which helps metabolize and eliminate a number of compounds, including many drugs. Too much of a toxin (such as alcohol) can damage the liver, causing some of the cells to die. Fortunately, as long as the damage is not too extensive, the liver can heal itself.
Blood Clotting
The liver is also an important source of proteins necessary for proper blood clotting, including prothrombin and fibrinogen. These proteins can detect breaks in blood vessels and cause other cells in the blood to clump together to help stop the flow of blood, thus preventing excessive bleeding. People with extensive liver damage often have trouble getting their blood to clot and may bruise or bleed very easily.
