Intestine

"The intestines are a long, continuous tube running from the stomach to the anus. Most absorption of nutrients and water happen in the intestines. The intestines include the small intestine, large intestine, and rectum.
The small intestine (small bowel) is about 20 feet long and about an inch in diameter. Its job is to absorb most of the nutrients from what we eat and drink. Velvety tissue lines the small intestine, which is divided into the duodenum, jejunum, and ileum.
The large intestine (colon or large bowel) is about 5 feet long and about 3 inches in diameter. The colon absorbs water from wastes, creating stool. As stool enters the rectum, nerves there create the urge to defecate."

Enteritis

Enteritis is inflammation of the small intestine. Enteritis is usually caused by eating or drinking substances that are contaminated with bacteria or viruses. The germs settle in the small intestine and cause inflammation and swelling.
Enteritis may also be caused by:
1. An autoimmune condition such as Crohn's disease
2. Certain drugs, including ibuprofen, naproxen sodium, and cocaine
3. Damage from radiation therapy.