The human digestive system works by introducing water and enzymes into food in order to extract nutrients and minerals from it. This process is assisted by smooth, involuntary muscles along the tract that help push food along. All waste products are excreted at the end of the digestive cycle. Charts that show the inner workings of the digestive system make it easier for students to visualize precisely how the process works. This may be easier for some people to understand by visualization, rather than relying on written descriptions.