The bacteria, yeasts, and fungi that normally grow in the intestines and colon.

The sugar found in milk. The body breaks lactose down into galactose and glucose.

The place on a chromosome where a specific gene is located, a kind of address for the gene. The plural is “loci.”

The lining of gastrointestinal tract organs that absorb nutrients and fluid, form a barrier, and produce mucus.

An irritation of the pancreas that can cause it to stop working. It is most often caused by gallstones or alcohol abuse.

A wavelike movement of muscles in the gastrointestinal (GI) tract. Peristalsis moves food and liquid through the GI tract.

Medicines that cause muscles in the gastrointestinal tract to move food. Examples are bethanechol and metoclopramide. (Brand names: Duvoid, Reglan.)

The surgical removal of an organ.

The organ where most digestion occurs. It measures about 20 feet and includes the duodenum, jejunum, and ileum.

The abnormal narrowing of a body opening. Also called stenosis.