The primary purpose of the gastrointestinal tract is to digest and absorb food. In order to fulfill this purpose, food must be ground, mixed, and transported through the intestines, where it is digested and absorbed. In addition, undigested and unabsorbed portions of the food must be eliminated from the body.
In functional diseases of the gastrointestinal tract such as Irritable Bowel Syndrome Symptoms, the grinding, mixing, digestion, and absorption functions are disturbed to only a minor degree. These functions are essentially maintained, perhaps because of a built-in over-capacity of the gastrointestinal tract to perform these functions. The most commonly affected function in these diseases is transportation. In the stomach and small intestine, the symptoms of slowed transportation are nausea, vomiting, abdominal bloating, and abdominal enlargement. The symptom of rapid transportation usually is diarrhea. The interpretation of symptoms, however, may be more complicated than this. For example, let’s say that a person has abnormally rapid emptying of the stomach. The sensing of this rapid emptying by the intestinal sensory nerves normally brings about a motor nerve response to slow emptying of the stomach and transportation through the small intestine. Thus, rapid emptying of the stomach may give rise to symptoms of slowed transportation.
In the colon, abnormally slowed or rapid transportation results in constipation or diarrhea, respectively. In addition, there may be increased amounts of mucus coating the stool or a sense of incomplete evacuation after a bowel movement.
Other researchers argue that the cause of functional diseases is abnormalities in the function of the motor nerves. For example, abnormal commands through the motor nerves might produce a painful spasm (contraction) of the muscles. Still others argue that abnormally functioning processing centers are responsible for functional diseases because they misinterpret normal sensations or send abnormal commands to the organ. In fact, some functional diseases may be due to sensory dysfunction, motor dysfunction, or both sensory and motor dysfunction. Still others may be due to abnormalities within the processing centers One area that is receiving a great deal of scientific attention is the potential role of gas produced by intestinal bacteria in patients with IBS. Studies have demonstrated that patients with IBS produce larger amounts of gas than individuals without IBS, and the gas may be retained longer in the small intestine. Among patients with IBS, abdominal size increases over the day, reaching a maximum in the evening and returning to baseline by the following morning. In individuals without IBS, there is no increase in abdominal size during the day.
Sometimes irritable bowel syndrome is referred to as spastic colon, mucous colitis, spastic colitis, nervous stomach, or irritable colon.IBS is also associated with non-gastrointestinal conditions such as headache, low back pain, arthritis, non-cardiac chest pain, difficult urination and fibromyalgia.
Dietary fat in healthy individuals causes food as well as gas to move more slowly through the stomach and small intestine. Some patients with IBS may even respond to dietary fat in an exaggerated fashion with greater slowing. Thus, dietary fat could–and probably does–aggravate the symptoms of IBS.