common bile duct. The common bile duct then usually joins with the duct of the
pancreas as the fluid enters the duodenum.
The pancreas is a soft, pliable organ stretched across the posterior wall of the
abdomen. When called upon, it secretes its powerful digestive fluid, known as
pancreatic juice, into the duodenum. Its duct joins the common bile duct.
Section V. THE LARGE INTESTINES
6-12. GENERAL FUNCTION
The primary function of the large intestines is the salvaging of water and
electrolytes (salts). Most of the end products of digestion have already been absorbed
in the small intestines. Within the large intestines, the contents are first a watery fluid.
Thus, the large intestines are important in the conservation of water for use by the body.
The large intestines remove water until a nearly solid mass is formed before defecation,
the evacuation of feces.
6-13. MAJOR SUBDIVISIONS
The major subdivisions of the large intestines are the cecum (with vermiform or
"worm-shaped" appendix), the ascending colon, the transverse colon, the descending
colon, and the sigmoid colon. The fecal mass is stored in the sigmoid colon until
passed into the rectum.
6-14. RECTUM, ANAL CANAL, AND ANUS
Rectum means "straight." However, this six-inch tubular structure would actually
look a bit wave-like from the front. From the side, one would see that it was curved to
conform the sacrum (at the lower end of the spinal column). The final storage of feces
is in the rectum. The rectum terminates in the narrow anal canal, which is about one
and one-half inches long in the adult. At the end of the anal canal is the opening called
the anus. Muscles called the anal sphincters aid in the retention of feces until