We need oxygen every moment of our lives, yet we don't even need to think about breathing! The brain makes sure our lungs keep working, whether we're aware of it or not. In this informative volume, readers will follow the path of a breath of air, both in and out of the lungs. Along the way, they'll learn biology vocabulary and the importance of body parts working together to provide the body with life-giving oxygen and rid it of carbon dioxide. Simple illustrations and photographs further elucidate this beginner's guide to the respiratory system.