In this section we’ve outlined details about the liver, including its location, functions, internal structure, and how it interacts with complementary organs in your body. To learn about liver diseases we treat with transplantation, please visit our “Liver Diseases” section.
Functions
The liver is, in essence, a gland. It performs over 500 functions, and produces over 1,000 enzymes. It is currently impossible to imitate the multifaceted role of the liver. Artificially sustaining life is impossible without it, although liver dialysis can be used for the short term. Some of its most important tasks include:
Many food nutrients digested in the intestines are carried into the liver via the portal vein to be converted into enzymes, minerals, vitamins, hormones, and other molecules that the body needs to function.
Some molecules are stored within the liver. Glycogen (a form of energy storage for cells), vitamins, and minerals are kept in the liver after a meal until needed by other organs.
The liver decomposes harmful substances, such as alcohol and poisons, into less harmful ones, returning the body to its normal function. The liver is responsible for breaking down about 90% of alcohol in the bloodstream, while the remainder gets exhaled through the lungs, or expelled through urine and sweat.
The liver creates the dark-green fluid that aids with the digestion of fats and other lipids in the small intestine. Without it, the body wouldn’t be able to absorb these nutrients.
Location
The liver is the largest internal organ in the human body, weighing between 3.2 to 3.7 pounds. It is located in the right upper quadrant of the abdominal cavity. The liver lies just below the diaphragm, to the right of the stomach and on top of the gallbladder. Its top side spreads from left ribcage to right ribcage, and its bottom corner ends at the bottom of the right ribcage.
Self-regeneration
The liver is the only internal organ capable of full regeneration. As little as 25% of a liver can regrow into a full liver. Through the process of compensatory growth, the remaining portion of the liver regrows to make up for the body's functional demand. The regenerated liver will not recreate the missing lobes, but will enlarge the existing portion until complete function is restored.
This regenerative property is the essence of live-donor adult liver transplant (LDALT), where only a portion of the donor’s liver is transplanted into the recipient. Both livers will regenerate in volume and return to normal function in a matter of months.
Lobes
The liver is divided into four lobes, all of which perform the same functions mentioned above. The left and right lobes are easily distinguished on the front side, since they're divided by the falciform ligament. The caudate and quadrate lobes can only be seen from behind the liver; the caudate is positioned in the upper back side, and the quadrate is found in the lower back side.
Blood Vessels
The liver receives 25% of its blood supply from the hepatic artery. The remaining 75% comes from the portal vein, which brings blood from the intestines, spleen, and pancreas, carrying essential nutrients from food that the liver uses in enzyme production. Blood is then taken away through the hepatic vein, back to the heart, where all the molecules produced are distributed throughout the body.
Biliary Structure
Bile produced in the liver flows out through a system of vessels named the biliary tree (due to its tree-like structure). These vessels, individually, are hepatic ducts, and they all merge to eventually form the common hepatic duct. If bile isn’t needed for digestion at the moment, it will flow up the cystic duct to be temporarily stored within the gallbladder. Once needed, this bile will flow to the duodenum via the bile duct, where it aids in digestion of fats.
Supplementary Organs
When needed for digestion, bile will flow down the bile duct to meet the pancreatic duct and mix with a combination of digestive enzymes produced in the pancreas. This mixture enters the duodenum (the top part of the small intestine), where it mixes with food coming from the stomach, aiding in its digestion.