The document compares the digestive system and brain to parts of a school. It describes how:
1) The mouth, esophagus, stomach, intestines, liver, pancreas, and rectum each break down and move food through the body like students move through areas of the school.
2) The brain sends messages through the thalamus, cerebrum, cerebellum, and brain stem to control the digestive system, similar to how announcements, the school board, gym, and secretary direct activities.
3) The digestive system and brain work together, with the brain sending messages to allow the digestive system to function, just as the school functions under coordinated leadership.