The Intestinal System
Lesson 7, Page 1 of 5

The intestinal system extends from the stomach to the anus and includes both the small and large intestines. The small intestine is involved with the digestion and assimilation of food. The large intestine is primarily involved with the storage and disposal of waste material. The small intestine was covered in the lesson on the digestive system. For the remainder of this lesson, we will concern ourselves with the large intestine.

Outline of Lesson

  1. Introduction
  2. What is the Function of the Colon?
  3. What are the Keys to Colon Health?
  4. What are Some Things That Can Go Wrong with the Colon?
  5. What the Experts Say
  6. Conclusion
    • Lifestyle Suggestions - Video
    • Intestinal System Product List
    • Assignments
    • Recommended Reading
    • Word Review List
  7. The Intestinal System Flow Chart
  8. Self-Evaluation


The large intestine, also known as the lower bowel or colon, is anatomically divided into the cecum, the ascending colon, the transverse colon, the descending colon, the sigmoid (meaning "S-shaped") colon, the rectum, and the anus.

A typical adult colon is approximately five feet long. It is not as long as the small intestine, which typically measures 20 feet in length; but the colon is about two and a half inches in diameter—or three times larger than the diameter of the small intestine—and that is why it is referred to as the "large intestine."

By the time the food reaches the colon, it is in a semi-fluid state and is referred to as chyme. The chyme passes from the small intestine to the colon via the ileocecal valve. This valve opens and closes by the action of a sphincter muscle, which allows the chyme to pass from the small intestine to the colon while keeping the contents of the colon from backing up into the small intestine.

The colon is also known as the large intestine because
it is longer than the small intestine.
its diameter is three times larger than that of the small intestine's.
it was named after the man who discovered it, Dr. Edmond Large.

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