"Did you know that there are approximately 500 species of bacteria in the intestines? The surface area of the small intestine is 2,700 square feet (250 square meters). Discover more fascinating facts in How the Human Body Works - The Digestive System. This series 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"--