The answer is obvious. Many of the organs transplanted are organs that people cannot live without. These organs are transplanted from people who have passed on and left it their will to transplant certain organs from their body.
kidney and heart
Organs and tissues successfully transplanted since 1950 include the heart, liver, kidneys, lungs, pancreas, and corneas. Currently, the most commonly transplanted organs are the kidneys and livers due to the high demand for these organs and the success rates of the procedures.
The skin
The most commonly transplanted organs include kidneys, liver, heart, lungs, and pancreas. These organs are often transplanted to patients suffering from organ failure or life-threatening conditions.
To be transplanted on another human being.
yes
All organs have been successfully transplanted except the brain.
Hearts, liver, kidneys, lungs, small intestine, pancreas, corneas, heart valves. Some other things have been transplanted (both successfully and unsuccessfully), but typically only "life saving" organs are routinely transplanted.
Routinely transplanted organs are: heart, kidneys, liver, lungs, pancreas, small intestine and cornea. Other transplants are available, but are not routine. Some organs are just not routinely transplanted because you can live without them, e.g stomach, bladder, spleen, colon etc... (Yes, you can live without your stomach, it's only the small intestine which is necessary for food absorption.)
tissues or whole organs transplanted from one species to another =D
No, not vital organs. Just kidneys and stuff like that. P.S. GO SLAPPY!