Look at it this way, anyone that gets split in half with a tree is not living for over 20 seconds. Only reason Tsunade is alive is because of Byakugo..
not exactly. The heart and lungs will still be working, but the amount of blood in the body will be reduced very quickly.
As I said, The brain cannot survive over 10 seconds without oxygenated blood, and it will take a bit of time before all of the blood in the body is expelled. I say that a person who is split in half has a total time of 2-3 minute to live.
Attacking a heart, brain or lungs on the other hand, will kill the person much faster.
Without the lungs, the body will not have any oxygenatied blood remaining to feed the brain in about 15 seconds, so they probably have only 30 seconds to live.
without the heart to pump blood, there wouldnt be any oxygenated blood moving throught the brain to nurish it, so they would die even quicker than that
severe damage to the brain can spell instant death or give the person only moments of life to live.