Liver

Liver

The liver is an organ that performs many functions. It produces bile to aid digestion. It extracts toxins and synthesizes nutrients in the blood. When necessary, the liver also breaks down glucose, which gives the body energy. One of the symptoms of liver disease is lethargy and lack of energy.

The liver is attached to the lower part of the diaphragm and takes up almost the entire upper right section of the abdominal region. It is divided into two parts, or lobes, and resembles a triangle in shape. The liver is about 2 percent of an adult's body weight; roughly 2.5 to 3 pounds. It is about 3 to 4 percent of a child's body weight.

The liver can remain viable for up to 12 hours outside the body.

-UNOS

There were 17,033 people on the national waiting list for a liver transplant as of April 2003, according to data from the Organ Procurement and Transplantation Network. In 2000 there were 4,536 liver transplants from deceased donors performed; in 2002, 4,968 were performed, according to OPTN data.

The first living donor liver transplant, in which a portion of the donor's liver is transplanted, was performed in 1989. In 2000, 385 living donor liver transplants were performed. The number jumped to 518 in 2001 and fell back down to 358 in 2002.

The liver's ability to regenerate itself also makes it an ideal organ for a living donation. For the donor, the liver grows back and regains full function.

This is probably because most of the other organs of the body are made up of specialized sub-organs to some extent, says Dr. Nicholas Jabbour, a liver transplant surgeon at the University of Southern California. Consider the kidney. It is divided into glomeruli, which are basically kidney units, and the sum of them will perform the functions of the kidney, he says.

The liver, on the other hand, is made up of many cells each of which does everything the liver does, Jabbour says. Hepatocyte and Kupffer cells are the liver's principal cell types and both can regenerate.

"Each one is a complete organ by itself," Jabbour says. "The hepatocyte is a cell that does what the liver does. Even without removing part of the liver, it will regenerate itself anyway, because the cells of the liver don't have an unlimited life span."

In many cases, a liver from a small child would be preferred to those of adults because the longer a person lives, the longer the cells must duplicate themselves. The organ also accumulates fat and debris. All these events lead to the liver becoming less functional over time.

"Even so, the liver from brain-dead patients over age 70 have been implanted and function properly," Jabbour say. "That is why we don't exclude brain-dead donors purely based on age."