SMALL INTESTINE--PRIMARY ORGAN
a. The major parts of the process of digestion and absorption take place in the
small intestine. This organ is a tube about one inch in diameter and 20 feet long. Refer
to figure 1-1 for position of the small intestine.
b. There are three major divisions in this organ: the duodenum, the jejunum,
and the ileum. The duodenum, about ten inches long, is the upper-most part of the
small intestine and is attached to the pyloric end of the stomach. The jejunum, about
eight feet long, begins at the point where the small intestine turns abruptly forward and
downward. The ileum, the third part of the small intestine, is about 12 feet long. Villi,
finger-like projections from the membrane covering the inside of the small intestine,
increase the surface area of the intestinal wall. This allows larger amounts of digested
nutrients to move into the wall of the small intestine.
LARGE INTESTINE--PRIMARY ORGAN
a. The large intestine is the broad, shorter part of the intestines. This tube-
shaped organ has a diameter of about two and one half inches and is about five to six
feet long. The large intestine extends from the ileum to the anus. See figure 1-1 for
position of the large intestine.
Figure 1-4. Large intestine.