Did you know the average adult takes 12 to 20 breaths per minute when not doing physical activity? Adults take between 17,000 and 23,000 breaths per day. Discover more fascinating facts in Respiratory System, a title in the Body Systems series. Each title in Body Systems guides readers through the fascinating inner workings of the human body. The human body contains several complex systems that work closely together to support life and allow the body to function properly. Each book explores the characteristics and interactions of these systems, their makeup, and their importance. This is an AV2 media enhanced book. A unique book code printed on page 2 unlocks multimedia content that brings the book to life. This book comes alive with audio, video, weblinks, slideshows, activities, quizzes, and much more.