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Response 1: When your heart stops beating, the blood stream to you brain is cut off. On average you get 70mL of blood every pump. The brain needs about 20% of that blood pumped. When blood is pumped it carries oxygen with it. After the blood is used up, it returns to the heart and is refilled with oxygen to be used again. When your heart stops, the blood can't return to the heart and stays where it is. When this happens, the brain doesn't receive oxygen. The oxygen in the blood is what feeds the brain. So when your brain doesn't get enough oxygen, it experiences brain damage. If the heart were not pumping, the oxygen in the stagnant blood would be used up by the cerebral cortex in two minutes. The nerve cells in the mid brain that control unconscious activity such as breathing can last thirty minutes and the nerve e cells in the spinal cord can last an hour without blood flow. The brain has no way of storing oxygen. So when your heart stops, you have until your brain completely runs out of oxygen before you are physically dead. You are alive until your brain is dead. It takes two minutes for the brain to die after the heart stops.

Ethan Barlow 8.3

Additional Responses:
The heart beats to push blood throughout the body. All tissues require delivery of oxygen and nutrients via the blood to survive. The most sensitive organ to blood flow is the brain. If the heart stops, the blood flow to the tissues ceases. The brain can only survive for a few minutes without blood flow and resuscitation of the heart so that it beats again would eventually not be possible.

Taylor Fraser 8.3
Expert - Douglas Fraser!

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