Overview of Vomiting
Vomiting, also called emesis, occurs with many types of gastrointestinal disorders and other conditions. Feelings of nausea often precede vomiting, which involves ejecting material from the stomach out of the body through the mouth (called vomit or vomitus).
In some cases (e.g., bowel obstruction), contents of the intestines also are ejected during vomiting. In addition to normal contents of the digestive system, vomit sometimes also includes blood from the GI tract and bile (fluid secreted by the liver).
Vomiting is a reflex that results from a combination of voluntary and involuntary muscles. First, a valve in the throat (called the glottis) closes to help prevent vomit from entering the windpipe (trachea) and lungs. Then, the muscle that surrounds the opening of the esophagus into the stomach (called the lower esophageal or cardiac sphincter) relaxes and the diaphragm (muscle that separates the chest from the abdomen) and various abdominal muscles contract in waves (called retching). Retching without producing vomit is called dry vomiting or dry heaves.