Step inside the human body to see how your brain and vascular system are vitally linked to keep you alive and well. Though your brain occupies only 5% of your body, it needs 20% of the blood supply to function properly. When that blood supply is restricted or blocked, the life-giving oxygen in the blood can’t get to the delicate brain tissues that need it. The tissues start to die, and parts of the brain stop working. You can think of a stroke as the same as a heart attack, except it happens in your brain. In this video, you can see a stroke "in action," understand the different types of strokes, the causes, the symptoms to look for, what to do in an emergency and what you can do to avoid one.