Just think, every single thing you do is handled by an amazing computer inside your head—your brilliant brain! And it's helped by your body's internet—your

Muscles help you run, jump, play sports, and even sit still long enough to read this book. Your bony skeleton holds you up and keeps everything in its place. Le

All day long, the human body is sending messages between the brain and other body parts. These messages control the body's movements and many other basic functi

Food is the body's fuel—but what happens to each yummy mouthful from the moment you take a bite? The Stickmen unravel the long process of digestion carried ou

Ba-boom, ba-boom, ba-boom . . . your incredible heart beats more than once every second, no matter what you're doing. And your lungs pull in up to 145 gallons o