what fuel used by the brain
Brain Tour. 2. Supply lines. Your brain is nourished by one of your body's richest networks of blood vessels. With each heartbeat, arteries carry about 20 to 25 percent of your blood to your brain, where billions of cells use about 20 percent of the oxygen and fuel your blood carries. When you are thinking hard, your brain may use up to 50 percent of the fuel and oxygen.