Why do brain cells die so quickly while other body parts can survive without blood for much longer?
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they do the most work.
Your muscles dont demand much when the body is in a resting state so your heart cells dont have to be super active outside of baseline stasis if need be. But your brain is responsible for constant sympathetic and parasympathetic response regardless of you being awake or sleeping etc.
The brain is only 5% of your body mass yet it consumes 20% of all the oxygen in your blood stream. The brain uses so much energy that without a near constant supply of blood, it will die in only a minute or so.
Actually, while it is true that the brain uses a lot of oxygen, it turns out that lack of oxygen isn’t what causes death to occur so quickly. It is actually getting oxygen that kills the brain quickly.
It turns out that as your brain starves for oxygen, the cells in the brain slow down more and more. When oxygen returns, the cells grab it and rev up activity.
However, if your brain is starved for oxygen for more than about five minutes, this revving up triggers the brain cell’s defenses against brain cancer. Certain cell activities running amok mean cancer to these defenses, and so the cell valiantly martyrs itself to save the brain from its cancerous self. It is rather like shooting yourself in the head to save your friends when you have the zombie plague.
This is what causes the phenomenon of cold water drowning, where a person can be underwater for up to thirty minutes without suffering brain damage. What happens is that when oxygen gets to the brain, everything is slowed by the cold. The revving up is held back by this, and thus the cell doesn’t panic about cancer and doesn’t suicide.
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