The digestive system is the part of our bodies in which the food we eat is so changed that it can be made use of by the little cells in the body. It is composed of a long canal with many parts and enlargements, each part necessary for a certain required work. This canal as a whole is called the alimentary canal.
Teeth
The mouth does the first part of the work for the digestive system. Here we find the teeth, which are used for grinding the food. The teeth are composed of three parts, the head (or crown), the neck and the root. The head, or crown, is very hard. Each tooth is hollow, and in the hollow portion there are nerves and blood vessels.
The salivary glands
Opening into the mouth are three pairs of glands known as salivary glands. One pair of glands is located just above the angle of the jaw. It is these glands that become swollen when we have mumps. Another pair of glands is placed just inside the jaw bone, near the root of the tongue, and the third pair is located under the tongue. These three pairs of glands secrete the saliva which moistens the food and aids in digesting the starch.
Fig. 82. The alimentary canal.
The esophagus
The food passes from the mouth; through a passage called the esophagus, or gullet, to the stomach.
The stomach