How Stroke Happens Strokes occur in the brain. Although your brain represents just 2 percent of your total body weight, it receives about 20 percent of the your entire body's blood supply. That's because your brain controls every action your body makes, from walking and talking to breathing and that constant blood flow provides the brain with the essential nutrients it needs to keep functioning properly. A stroke, or Brain Attack, occurs when the blood flow to the brain is somehow disrupted and brain cells lose their supply of nutrients. This happens when the brain receives too little, or too much, blood.
Brain cells can only survive for a few hours in a state of non-function.
If this problem is not fixed within hours, brain cells die and there is permanent brain damage. Once brain cells die, they cannot be re-grown, revitalized or replaced. Ischemic stroke is more common and occurs when blood flow to the brain is blocked, often by a clot. Hemorrhagic stroke is less common, but more deadly, and occurs when there is bleeding into and around the brain itself. Both types of stroke can be caused by several factors and there are a variety of treatment options available for each of the causes.