6. What is brain death? Doesn't the person's heart have to stop for them to be dead?

A person is legally dead when a licensed physician, having carefully examined the person, declares that death has occurred. Before scientists learned that the brain could die before the heart stops, the only way of determining death was to observe the absence of heartbeat and breathing. Now we have learned that once the brain dies, the person is dead and cannot recover.

Brain death is death that results from the total, irreversible loss of all brain function. All of the brain cells die and cannot come back to life. Since the brain causes breathing, a brain dead person does not breathe spontaneously. However, if a mechanical machine called a ventilator (also called a respirator) is used to breathe for the person, the heart will still beat for a period of time after they become brain dead, and the other organs such as the kidneys and liver will continue to function normally. It is this relatively rare kind of death that makes organ donation possible.

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