Human Body: Pushing the Limits

The human body is engineered for strength, power and endurance. Bone is sturdy as concrete but flexible enough to resist breaking and light enough to allow us to be quicker off the mark than a racehorse. Our muscles, ligaments and joints have far greater strength and endurance than we know. In this episode, we feature extraordinary tales of human strength told with stunning see-through "anatomy in motion."

Sight is the king of the senses. More than 80 percent of what we know of the world comes through our eyes -- without our sight we're lost. In this episode, we reveal the inner workings of our visual system as they've never been seen before, vividly confirming that ancient human adaptations prove no less crucial in modern life.

Less than one-twentieth of an inch below the surface of the skin are the "antennae" that allow us to sense the world around us. This vital layer is the gateway to the original information superhighway -- the nervous system. Millions of nerves carry sensations across the body and up to the brain at hundreds of miles an hour. But our nervous system also has abilities almost beyond imagining.