The Digestive System: An Overview
Life is all about using energy. The energy that your body uses comes from the food
you eat. This food or fuel is broken down to release its energy and to create
building blocks for cell growth and repair in the digestive system.
The digestive system makes your body somewhat like a donut with a hole running all
through you body. This hole is called the digestive tract and is composed of
numerous parts. Look at the diagram on page 847 and list what each of the
following parts do.
In addition to this hole you have accessory organs that help the digestive tract do its
job. List the accessory organs and say what they do.
Read about the functions of the digestive system on page 846 and summarize each in
the space below.
2. Mechanical Processing
If you cut the digestive tract crosswise, you will discover that it has four layers
including (1) the mucosa, (2) the submucosa, (3) the muscularis externa, and (4)
the serosa. Read about each of these layers and complete the table below:
Wall Layer Subdivisions of the layer Major Functions
The two layers of smooth muscle in the muscularis externa play an important role in
moving material along the digestive tract. The two layers are arranged in
different directions. The Inner layer is arranged so that the muscle fibers run in a
____________ while the outer layer has muscle fibers that run
The contractions of these two layers create two different kinds of movement.
Movement through _______________ helps move material along the tract and
_________________ helps in the mechanical processing of material.
Describe these two kinds of movement below: