Living Donation Some organs and tissues can be donated by living people. A healthy body easily replaces blood, blood platelets, and bone marrow, so they can be donated more than once. A person can donate a single kidney or part of the liver while alive. The remaining kidney can provide some of the function of the donated kidney, and the liver grows back (regenerates) to its original size in a few weeks. It is also possible to donate part of one lung, part of the pancreas, or part of the intestine, although these organs do not regenerate. It is also possible, although unusual, for a living person to donate a heart. People with severe lung disease may receive a combined heart and lung transplant because outcomes may be better in some cases if the heart and lungs are transplanted together. If the heart-lung recipient's own heart is in good condition, it may be donated to an individual who needs a heart transplant alone. Blood stem cells from the bone marrow or circulating blood of volunteer adults or from umbilical cord blood after the birth of a healthy baby are available for transplantation. Each potential living donor is assessed to determine his or her suitability to donate. Generally, living donors should be physically fit, in good health, between the ages of 18 and 60, and not have or have had diabetes, cancer, high blood pressure, kidney disease, or heart disease. Since the first successful kidney transplant in 1954, and as a result of the growing need for organs for transplantation, living donation has become a common alternative to deceased donor transplantation. Of the 24,817 transplants performed in 2004, around a quarter of the organs (6,406) were from living donors. Single kidney donation was the most frequent living donor procedure. Donation after brain death Most of the organs used in transplants come from people who have suffered brain death as the result of an accident, heart attack, or stroke. Brain death is total cessation of brain function, including brain stem function. There is no oxygen or blood flow to the brain; the brain no longer functions in any manner and will never function again. The organs and tissues that are in good condition are removed in a surgical procedure and all incisions are closed so an open casket funeral can take place. After the organs have been removed, the patient is taken off artificial support. While organs must be used between 6 and 72 hours after removal from the donor's body (depending on the organ), tissues such as corneas, skin, heart valves, bone, tendons, ligaments, and cartilage can be preserved and stored in tissue banks for later use. Donation after cardiac death (DCD) Some patients that have sustained traumatic brain injury cannot be declared dead based on the definition of brain death. In these cases, the patient is declared dead upon cardiac death, which is the cessation of cardiac and respiratory function when the patient is withdrawn from life support. Donation after cardiac death occurs only after the patient or family has decided to withdraw life-sustaining therapies for reasons entirely apart from any potential for organ donation. Whole body donation People who wish to donate their entire body to medical science should contact the medical school or willed body program of their choice and make arrangements to do so before they die. Medical schools need bodies to teach medical students about anatomy, and research facilities need them to study disease processes so they can devise cures. Since the bodies used for these purposes generally must be complete with all their organs and tissues, organ donation is not an option. Some programs, however, make exceptions. You can inform your family that organ donation is your first choice, but if it is found that you are not medically suitable for organ donation, your family can carry out your wishes for whole body donation.