When an organ in the human body gets irreparably damaged, the only way out would be replacement with a healthy organ i.e., Transplantation. The only way to obtain an organ is through an act of charity, Organ donation. Organ donation can be one of the four types
A kidney or a part of the liver can be removed safely from a healthy volunteer and transplanted in to a patient whose organ has failed. Such is the reserve capacity of the body, that the remaining kidney or portion of the liver will take over the whole function immediately. This is similar to blood donation. It is essential that the donor is investigated thoroughly to estimate the function of the remaining organ and suitability of the organ to the recipient.
After brain death:
A vital part of the brain, brain stem some times gets irreversibly damaged due to trauma, or a sponataneous bleed. In such condition all purposeful body movements and breathing cease. If left unintervened, eventually all other organs including heart stop functioning. The person is said to be brain dead. How ever the functioning of organs can be prolonged for a few days with the support of a breathing machine. The organs of the deceased in such a situation can removed and transplanted into a suitable patient
After cardiac death:
The more common mode of death is by cessation of heart beat. Once the heart stops, the rest of organs become dysfunctional with in minutes due to lack of blood supply. However cornea, bone and skin grafts can be taken and stored for transplantation.
Non-heart beating donation:
'Procurement of organs for the purpose of transplantation after withdrawal of treatment in terminally ill patients who have no chance for recovery', is legal in some parts of the world. This is not an option in India .