The liver is the largest vital organ. A vital organ is one that organisms cannot survive without. It is found in the abdomen of all vertebrates. The liver has many functions, some of which are very complicated. Some of its main functions are to clear toxins from the body and to regulate body metabolism. The liver also filters blood from the digestive system.
Liver as food
Liver is high in iron and Vitamin A and animal liver is often eaten by human beings. Incidentally, the concept of hypervitaminosis arose from the lethal adverse effects of consuming the liver of polar bear  and sled dogs .
Disorders of the liver
Nonsurgical diagnosis and treatment of liver disease comes under the purview of the medical specialty of gastroenterology; liver disorders are sometimes considered a tertiary specialty of hepatology.
Physical examination may be difficult as much of the liver is protected by the ribs, but the lower edge may be palpable just below the rib cage. Percussion can detect hepatomegaly. Abnormal percussion is percussing in the mid-clavicular line to more than 12 cm by soft percussion or 9 cm by hard percussion; however, size varies by gender and lean body mass. An enlarged liver, may extend well below the last ribs and be detected by palpation.
Liver disease can affect the skin. If there is a disorder of bile metabolism, the pigments involved may produce jaundice, a yellow discoloration of the skin and possibly of the whites of the eyes. Another skin symptom can be red-purple patches that appear to radiate lines of the same color; they suggest the body and legs of a spider and are called spider angiomas. Inadequate liver function can also produce severe itching.
Liver function tests principally measure serum enzymes that are normally present in hepatocytes, or liver cells, and are released when the cells are destroyed. Many of these enzymes, such as alanine aminotransferase, lactic dehydrogenase and aspartate aminotransferase occur in other tissues, so the diagnostician looks for a pattern of multiple elevations that would be common to the liver alone.
Destruction of hepatocytes, however, is not the only reasons these enzymes may be elevated. Increased alkaline phosphatase, for example, is more indicative of obstructions to flow in the organ than destruction. Elevated bilirubin, both in serum and urine, is another indication of obstructive disease.
- NEJM -- Hypervitaminosis A and Fractures.
- sBMJ -- Man's best friend?.
- Castell DO, O'Brien KD, Muench H, Chalmers TC (1969). "Estimation of liver size by percussion in normal individuals.". Ann Intern Med 70 (6): 1183-9. PMID 5795743.