Anatomy Intestine

The list below describes parts of the intestinal system and their function. For other terms related to the intestinal system, see the list of intestine terminology.

Bowel: This is another name for intestine. It is part of the alimentary canal, the long tube that extends from the mouth to the anus, and aids in digestion. The bowel has two parts: the small intestine and the large intestine.

Colon: This is the main part of the large intestine, and is comprised of four sections: ascending, transverse, descending and sigmoid. While the colon does not contribute to food digestion, fluids from undigested foods are absorbed here. The colon has peristaltic action, which pushes the stool closer to the rectum to be expelled.

Ileum: The final segment of the small intestine.

Large Intestine: Forming the lower part of the digestive system, the large intestine consists of the cecum, ascending colon, transverse colon descending colon, sigmoid colon and rectum. The primary function of the large intestine is absorbing water and electrolytes.

Mucosa: The lining of the gastrointestinal tract, the mucosa is a moist layer of epithelial (surface) cells with digestive functions and glands that secrete mucus. Layers of connective tissue lie under the mucosa.

Mucus: A protective barrier covering the membranes in the intestines. A viscous fluid secreted by the mucous membranes.

Perianal: The area near or around the anus.

Rectum: The last part of the large intestine, right after the sigmoid colon, the rectum connects to the anal canal. The rectum is where the fecal material is stored before it is released.

Small Intestine: Extending about 20 to 25 feet, the small intestine is made up of three parts: the duodenum, the jejunum and the ileum. This is where the absorption of nutrients from the foods we eat occurs.

Sphincter: Muscles that form a ring around the orifice of the anus.

Villi: These are tiny finger-like projections along the inside surface of the small intestine, which increase the surface area allowing for better and faster absorption of nutrients.