Science and Profession (Magill’s Medical Guide, Sixth Edition)
The gastrointestinal (GI), or digestive or alimentary, tract is a hose of layered membranes, about seven to nine meters long, that runs from the throat to the anus, allowing matter from the external world to pass through the human body. Along with its allied organs, glands, and nerve networks, the GI passage extracts the nutrients from food that are needed to fuel the body and excretes any substances that are left over. Physicians specializing in the GI system, gastroenterologists, care for everything from the upper esophageal sphincter to the anus; other specialists care for the mouth.
The GI tract has five major sections, each performing a different service: the esophagus, the stomach, the small intestine, the colon, and the anorectum. The esophagus begins where the throat ends, just below the vocal cords. It is a straight tube, about 20 to 22 centimeters long, with a valve at the top (upper esophageal sphincter). When food, formed into a ball and softened by chewing, enters from the mouth, rhythmic waves of muscle contractions (peristalsis) squeeze it smoothly toward the stomach, a trip that lasts about seven seconds. Peristaltic pressure triggers the lower esophageal sphincter to open, dropping the ball of food into the stomach; the sphincter immediately closes so that no stomach acids wash up into the esophagus.
The stomach, an ear-shaped bag that holds one to two liters of material, has three adjoining...
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Diagnostic and Treatment Techniques (Magill’s Medical Guide, Sixth Edition)
An extensive battery of tests, procedures, and medications enable gastroenterologists to cure or palliate many GI diseases. In addition to the traditional physician’s tools of the physical examination and the patient’s medical history, high-tech instruments let gastroenterologists see inside parts of the gut, produce images of it, remove tissue and stones, stop bleeding, and destroy tumors. Medicines kill bacteria, help regulate motility, speed the healing of damaged tissue, and control diarrhea and constipation. Yet the GI tract is a very intricate system, and at times the gastroenterologist’s most effective remedy is sympathy and advice about changing behavior or diet so that patients learn to live with their diseases.
Before treatment can begin, the disease must be identified. An interview with the patient and a medical examination constitute the first step in narrowing the range of possible causes of distressing symptoms. Symptoms described by the patient or discovered by the physician are clues to the underlying causes and suggest the kinds of tests that will most likely isolate the actions of a specific disease. Blood tests can reveal abnormal levels of white cells or chemicals and the presence of infection. Samples of digestive juices likewise can show chemical imbalances, infections, and bleeding, as can stool samples. Biopsies of the gut membrane, liver, and tumors allow pathologists to...
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Perspective and Prospects (Magill’s Medical Guide, Sixth Edition)
Jan Baptista van Helmont, a seventeenth century medical chemist, was the first to describe the diseases and digestive juices of the GI tract scientifically. Gastroenterology can be said to have started with his studies (he also coined the word “gas”). Yet no one directly observed the operations of digestion until 1833, when U.S. Army surgeon William Beaumont cared for a French Canadian with a bullet wound to the stomach. The wound remained open, and Beaumont could watch the action of gastric juices and the stomach’s mixing and grinding action. Throughout the nineteenth century, there were advances in the understanding and treatment of the GI tract, including the introduction of enemas and gastric lavage (washing out), X rays, and an early form of endoscopy.
As it did for most branches of medicine, twentieth century technology greatly expanded the role of gastroenterology in diagnosing, preventing, and treating disease. Imaging and endoscopy especially have revolutionized the field. In 1932, Rudolph Schindler developed a flexible gastroscope, and in 1943, Lester Dragstedt performed the first vagotomy (surgically cutting the vagus nerve) to reduce stomach acid secretions. Advances were also made to heal peptic ulcers with a special diet. The second half of the twentieth century saw an escalating number of refinements and innovations in procedures but was most remarkable for the development of drugs.
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For Further Information: (Magill’s Medical Guide, Sixth Edition)
Brandt, Lawrence J., ed. The Clinical Practice of Gastroenterology. 2 vols. Philadelphia: Current Medicine, 1999. Details virtually all of the adult and pediatric gastroenterologic problems encountered in practice. Features a full section on liver disease and synthesizes new advances in molecular immunology and imaging techniques.
Heuman, Douglas M., A. Scott Mills, and Hunter H. McGuire, Jr. Gastroenterology. Philadelphia: W. B. Saunders, 1997. This volume in the Saunders text and review series discusses digestive system diseases, the physiology of the digestive system, and the methods employed in the field of gastroenterology. Includes a bibliography and an index.
Janowitz, Henry D. Indigestion: Living Better with Upper Intestinal Problems, from Heartburn to Ulcers and Gallstones. New York: Oxford University Press, 1994. Janowitz discusses common ailments of the upper GI tract with special attention to degenerative diseases afflicting people as they age. His style is clear and straightforward, aimed at general readers who want to prevent illness or to manage an existing one. Accompanied by charts and illustrations.
Massoni, Margaret. “Nurses’ GI Handbook.” Nursing 20 (November, 1990): 65-80. Intended as a primer on GI problems for nurses, this article contains many illustrations of the gut, surgical techniques, and physical examination methods; lists of...
(The entire section is 309 words.)