Overview of Gastrointestinal Motility
The Enteric Nervous System
The ENS is a self-contained system within the gut with its own reflexes and control of movement. It controls motility, secretion, and sensation. The main "movement" of the gut is called peristalsis, the progressive wave of contraction and relaxation of the muscular gut tube, by which the contents are forced through the system.
Sensations from the gut are typically not perceived most of the time unless pain receptors are stimulated. These receptors are usually activated by stretching of the gut wall (called distension), cramping, or inflammation. Usually when the insult subsides, the pain does as well. In certain cases, silent pain receptors (called nociceptors) are activated that do not “turn off” after the insult has gone away, and the patient is left with a chronic pain situation. The reasons for this happening are not known, but this concept underlies many disorders of hypersensitivity, such as post-infectious Irritable Bowel Syndrome (IBS).
Abnormalities of gut motility, secretion, and sensation can lead to a wide range of diseases and disorders. These disorders can be from damage to nerves, muscle, or both of these ENS components. Very often motility problems may be due to drug side-effects, for example diarrhea from the antibiotic erythromycin which stimulates gut motility, or constipation from narcotics which suppress gut motility. Many motility disorders have no known cause but are very common (such as IBS). Some are less common but can be life-threatening, such as gastroparesis or intestinal pseudo-obstruction.
For a description of some of the major gut motility disorders, please click on the links to the left. For more information about digestive motility disorders, read the latest here.