Saliva
A mixture of water, protein, and salts that makes food easy to swallow and begins digestion.

Salmonella
A bacterium that may cause intestinal infection and diarrhea. See also Gastroenteritis.

Sarcoidosis
A condition that causes small, fleshy swellings in the liver, lungs, and spleen.

Schatzki's Ring
See Lower Esophageal Ring.

Scintigraphy
See Radionuclide Scans.

Sclerotherapy
A method of stopping upper GI bleeding. A needle is inserted through an endoscope to bring hardening agents to the place that is bleeding.

Secretin
A hormone made in the duodenum. Causes the stomach to make pepsin, the liver to make bile, and the pancreas to make a digestive juice.

Segmentation
The process by which muscles in the intestines move food and wastes through the body.

Shigellosis
Infection with the bacterium Shigella. Usually causes a high fever, acute diarrhea, and dehydration. See also Gastroenteritis.

Short Bowel Syndrome
Problems related to absorbing nutrients after removal of part of the small intestine. Symptoms include diarrhea, weakness, and weight loss. Also called short gut syndrome.

Short Gut Syndrome
See Short Bowel Syndrome.

Shwachman's Syndrome
A digestive and respiratory disorder of children. Certain digestive enzymes are missing and white blood cells are few. Symptoms may include diarrhea and short stature.

Sigmoid Colon
The lower part of the colon that empties into the rectum.

Sigmoidoscopy
Looking into the sigmoid colon and rectum with a flexible or rigid tube, called a sigmoidoscope.

Sitz Bath
A special plastic tub. A person sits in a few inches of warm water to help relieve discomfort of hemorrhoids or anal fissures.

Small Bowel Enema
X-rays of the small intestine taken as barium liquid passes through the organ. Also called small bowel follow-through. See also Lower GI Series.

Small Bowel Follow-Through
See Small Bowel Enema.

Small Intestine
Organ where most digestion occurs. It measures about 20 feet and includes the duodenum, jejunum, and ileum.

Solitary Rectal Ulcer
A rare type of ulcer in the rectum. May develop because of straining to have a bowel movement.

Somatostatin
A hormone in the pancreas. Somatostatin helps tell the body when to make the hormones insulin, glucagon, gastrin, secretin, and renin.

Spasms
Muscle movements such as those in the colon that cause pain, cramps, and diarrhea.

Sphincter
A ring-like band of muscle that opens and closes an opening in the body. An example is the muscle between the esophagus and the stomach known as the lower esophageal sphincter.

Sphincter of Oddi
The muscle between the common bile duct and pancreatic ducts.

Spleen
The organ that cleans blood and makes white blood cells. White blood cells attack bacteria and other foreign cells.

Splenic Flexure Syndrome
A condition that occurs when air or gas collects in the upper parts of the colon. Causes pain in the upper left abdomen. The pain often moves to the left chest and may be confused with heart problems.

Squamous Epithelium
Tissue in an organ such as the esophagus. Consists of layers of flat, scaly cells.

Steatorrhea
A condition in which the body cannot absorb fat. Causes a buildup of fat in the stool and loose, greasy, and foul bowel movements.

Steatosis
See Fatty Liver.

Stoma
An opening in the abdomen that is created by an operation (ostomy). Must be covered at all times by a bag that collects stool.

Stomach
The organ between the esophagus and the small intestine. The stomach is where digestion of protein begins.

Stomach Ulcer
An open sore in the lining of the stomach. Also called gastric ulcer.

Stool
The solid wastes that pass through the rectum as bowel movements. Stools are undigested foods, bacteria, mucus, and dead cells. Also called feces.

Stress Ulcer
(STRES UL-sur)
An upper GI ulcer from physical injury such as surgery, major burns, or critical head injury.

Stricture
(STRIK-sher)
The abnormal narrowing of a body opening. Also called stenosis. See also Esophageal Stricture and Pyloric Stenosis.