Required in very small quantities from outside the body are substances called
vitamins. These can be considered in two major categories--water-soluble and
Water-soluble vitamins include the B-complex vitamins, vitamin C, and others.
There is a daily requirement for water-soluble vitamins because they are continuously
excreted with the urine.
On the other hand, fat-soluble vitamins accumulate in the fat of the body.
An important nondigestible food material is cellulose, commonly referred to as
"fiber" or "bulk." Other undigested materials may be due to the consumption of great
quantities of food. Undigested food materials enter the large intestines through the
A major function of the large intestines is to salvage water. To facilitate
movement, mucus is added to the contents of the large intestines. Microorganisms in
the large intestines manufacture vitamin K. Some microorganisms can act upon certain
foods to produce gases. Feces is stored in the rectum and the lower portion of the
sigmoid colon. Defecation is accomplished by relaxation of the anal sphincter muscles.
End of Lesson 6