The Mouth and Esophagus

The teeth break down food into smaller pieces. Saliva moistens the food and changes it into a soft, pasty mass.

A special enzyme in the saliva called ptyalin changes the food partly into glucose. An enzyme is a substance that speeds up chemical reaction.

The tongue is a muscular organ that tastes, holds, and pushes food into the esophagus. The esophagus is a muscular tube about 25 cm long. From the esophagus, food is pushed to the stomach through a wavelike motion called peristalsis.