What Is
Death People in the past did not question the difference
between life and death. They could see that a person died when his heart stopped
beating. People have learned, however, that the body does not die immediately
when the heart stops beating. They discovered that we remain alive as long as
our brain remains active. Today the difference between life and death is not as
easy to see as in the past. Modern medical devices can keep the heart beating
and the lungs breathing long after the brain stops. But is this life
This question has caused much debate among citizens in the United States.
Many of them want a law that says a person is dead when the brain dies. A person
should be considered dead when brain waves stop even if machines can keep the
body alive. Such a law would permit doctors to speed removal (切除) of undiseased
(没病的) organs for transplant (移植) operations. The brain is made
of thousands of millions of nerve cells. These cells send and receive millions
of chemical and electrical messages every day. In this way the brain controls
the other body activities. Nerve-cell experts say it usually is easy to tell
when the brain has died. They put small electrodes (电极) on a person’s skull (头骨)
to measure the electrical signals that pass in and out of the brain. These brain
waves are recorded on a television screen or on paper. The waves move up and
down every time the brain receives messages from the nerve cells. The brain is
dead when the waves stop moving. Although there are people who
oppose the idea of a law on brain block for variouis reasons, the idea of brain
wave activity as a test of death is slowly being
accepted.
The brain controls the other body activities through______.
