The brain is the control center for everything from memories to movement, eyesight to emotions. This incredible computer processes messages from billions of microscopic cells called neurons, which link up to form nerves. Covering every inch of the body, nerves can carry messages from your fingertip to your brain and back at speeds of up to four hundred feet per second. With stunning full-color photographs and a fascinating text, award-winning author Seymour Simon continues his fantastic journey through the human body.