Digestive System (a True Book: Your Amazing Body)

"Digestion starts the minute you put food or a drink in your mouth. And by the time the process ends, your body has taken every bit of nutrition possible from your food. Did you know that the average person produces enough saliva in one year to fill a bathtub? Or that the small intestine is the longest part of the digestive system? Learn all this and more in Digestive System"--