It seems that what we thought we knew about death was wrong. It turns out that the cells of our body don't actually die that quickly when deprived of oxygen, they die quickly when the oxygen is restored.
How messed is that? Personally it boggles my mind.....anyway onward with the science :)
"But if the cells are still alive, why can't doctors revive someone who has been dead for an hour? Because once the cells have been without oxygen for more than five minutes, they die when their oxygen supply is resumed."