Digestion: Bill Nye explains how the body's digestive system is like a fine-tuned machine that turns food into energy. Bill demonstrates the process with a steam engine that runs on corn flakes. Respiration: Bill Nye gets aerobic about the importance of respiration as he jogs, bikes, swims, and scuba dives. Discover how to measure the amount of air each breath contains and see a demonstration of how cigarette smoke can infiltrate and injure the lungs.