Lungs allow us to speak, sing, talk, and so much more! Learn about how your respiratory system allows you to breathe.

Rachel Ray brings on an expert to her show to compare lungs of a healthy nonsmoker and those of a smoker of cigarettes. They look at the shape, color and texture to understand how smoking can affect the lungs.

The group escapes from hepatitis B and enters Alveoli Forest, where they encounter the bronchial tubes, alveoli, and the disease, tuberculosis. Dr. Bloom explains that the human has latent tuberculosis, as the disease is usually found in many people's lungs but is not active. He changes his opinion, however, when he sees that tuberculosis bacteria has escaped from its inactive state.

Using limited resources, the team at NASA needs to invent a way to fit a square cartridge into a round hole in order to create a CO2 filter. This filter would prevent the CO2 levels from rising too high in the spacecraft. Otherwise, the crew will face complications such as impaired judgment and blackouts.

Krishna Sudhir explains how cigarettes and their smoke damage lungs through the build up of tar, carbon monoxide, and chemicals.