Ｑ：Is there really the zombie that a human being who died once revives?？
Ａ：There is no zombie on this earth. Because most of the cells of the brain die when heart stops and blood is not able to be sent to the brain from the heart at all for 5-10 minutes.
Even if it passes more than 15-20 minutes, and heart begins to move again, the body does not move, and we cannot breathe by ourselves nor mostly respond.
It may be said that brain is a delicate organ.
２．Next, what is the autonomic nervous system which does not help with own intention?
For example, let’s watch a pupil when we move to the bright place from the slightly dark place. It becomes small, doesn’t it? If we move to the slightly dark place from the bright place, it becomes large. The pupillary size cannot be decided by one's intention.