Organs are systems of cells and tissues that perform a specific task -- respiration, for example, or ridding the body of waste. Organs are equipped with higher than necessary capacity. For instance, a 20-year-old's heart can pump 10 times more than the amount of blood needed [source: NLM]. This reserve capacity diminishes as we age, however. The heart, lungs and kidneys especially diminish over time, more so than other organs.
While organs deteriorate over a lifetime along with the rest of your body, disease or genetics may ultimately destroy one specific organ while the rest of your body remains relatively healthy. Depending on which organ is wearing down, there are many life-sustaining measures short of transplantation that can be taken to improve your health. For instance, dialysis helps a person with damaged kidneys. However, the rest of the body is negatively affected by these measures. A person on dialysis has a higher risk of cardiovascular disease because the process can reduce the amount of antioxidants that normally fight toxins within the body.
In many cases, the best (and sometimes the only) answer is to replace the damaged organ with a healthy one. Healthy organs aren't easy to come by, though. As of 2015, there were more than 116,000 people on waiting lists for organs [source: OPTN]. The wait period for 53.2 percent of the people added to transplant waiting lists in 2006 was longer than one year [source: UNOS].
Each organ has its own waiting list, but the lists share a common characteristic -- there are more organs needed than are available. Though many lives are saved through organ donation, many people die while waiting on a list. On average, about 106 people are added to an organ waiting list every day, and 18 people die each day waiting for an organ [source: LifeShare].
A person, living or dead, who provides an organ is called a donor. The person into whom the organ will be transplanted is the recipient. Collecting an organ from a donor is known as retrieval or procurement.
Almost anyone of nearly any age and average health can donate an organ. Anyone who has cancer, HIV or disease-causing bacteria in the bloodstream or body tissues is exempt from donation. Decisions about an organ's usability are made at the donor's time of death or, in the case of living donors, in the process leading to donation.
Most religious and spiritual groups either strongly endorse the act of donating organs or believe it's up to the donor to decide. Only a very few -- namely gypsies and Shinto -- are opposed to organ donation. (Gypsies do not have a formalized religion but do have a shared belief system in which the body is still needed in the first year of the afterlife as the soul retraces its steps.) The Amish support organ donation if there's a relative certainty of success for the recipient, but they're more reluctant if the probable outcome is questionable. Jehovah's Witnesses are not opposed to organ donation or transplantation, so long as the organs are first emptied of all blood [source: [Transplant for Life].
So how can you become an organ donor? And what organs you can donate before you give up the ghost? We'll find out next.