I used to work for an organ transplant company. The organs need to be harvested from "live" humans because they spoil quite rapidly without blood/oxygen going through them

Corneas, veins, skin, joints, and other non-critical parts are removed after the patient is well and truly dead.

My advice for everyone: do not sign the "I want to be an organ donor" line on your driver's license form. Let your family make that decision based on your wishes when the time comes.

You may be donating your body parts, but everyone else involved is making money from them. We know how corrupt the medical/pharmaceutical industries are. Don't give them a reason to kill you before your time.