What are intestinal disorders?

Process and Effects

Intestinal diseases and disorders are sometimes included with those of the digestive system. For the sake of clarity, this article makes the distinction between the structures of the digestive and intestinal tracts. The entire digestive tract, which includes the intestinal tract and is approximately 7.6 to 9.1 meters in length in adults, begins in the mouth and ends with the anus. It includes organs specific to digestion, such as the esophagus and stomach and their substructures. The intestinal tract, which constitutes the major part of the digestive tract, includes the small intestine, the large intestine (also known as the colon), and the organs that branch off these structures (the liver, pancreas, and gallbladder). The function of the small and large intestines is to break down food, absorb its nutrients into the bloodstream, and carry off waste products of digestion as feces.

The
small intestine is approximately 6.1 meters long and 3.8 centimeters in diameter and is made up of the duodenum, the jejunum, and the ileum. It is where the process of digestion begins in full. The smaller products broken down by the stomach are received by the small intestine, where they are absorbed into the bloodstream through its lining by villi combined with bile (from the liver) and pancreatic juices.

Almost all food nutrients are absorbed in the small intestine. What passes into the large intestine is a mix of unabsorbed nutrients, water, fiber, and electrolytes. Most of the moisture from this process is removed as the mix passes through the large intestine, leaving solid waste products. Before excretion as feces, approximately 90 percent of the liquid that entered the large intestine has been reabsorbed. This reabsorption is necessary for health because the liquid contains sodium and water.

The large intestine is approximately 1.5 meters long and connected to the small intestine at the ileocecal valve. Waste products from the digestive process pass through this valve into a large holding area of the large intestine called the cecum. The appendix is attached to this structure. The large intestine consists of the ascending colon (which begins on the right side of the abdomen and moves up toward the liver), the transverse colon (which crosses the abdomen), and the descending colon (which moves down the left side of the abdomen). The sigmoid colon is an S-shaped structure that connects to the descending colon and joins the rectum, a tube 12 to 20 centimeters long that leads to the anus. Small microorganisms in the large intestine break down waste products not broken down by the stomach and small intestines, resulting in gas (also known as flatus).

Complications and Disorders

Diseases and disorders of the intestinal tract constitute a major health problem affecting many individuals at one point or another in their lives. The common diseases and disorders that affect the intestinal tract include acute inflammatory disorders (such as appendicitis), diverticular disorders (diverticulosis and diverticulitis), chronic inflammatory bowel disease (Crohn’s disease and ulcerative colitis), intestinal infections (such as intestinal parasites and bacterial infections with Salmonella, Shigella dysenteriae, and Escherichia coli), intestinal obstructions, cancers or tumors of the rectum and colon, and polyps.

The most common acute inflammatory disorder is appendicitis. Its usually affects individuals between the ages of ten and thirty, and its symptoms include abdominal pain and tenderness, nausea and vomiting, loss of appetite, rapid heart rate, fever, and an elevated white blood cell count. Normally, the appendix, whose function is not clearly understood, fills and empties with food as regularly as does the cecum, of which it is a part. It sometimes becomes inflamed because of either kinking or obstruction, producing pressure and initiating symptoms. The most common major complication associated with appendicitis is perforation, which causes severe pain and an elevation of temperature. In these cases, a physician must be notified immediately. Treatment consists of surgical removal of the appendix.

Diverticular disorders include diverticulosis and diverticulitis. Diverticulosis is the presence of diverticula without any inflammation or symptoms. Diverticulitis is the result of an inflammation or infection of the intestine produced when food or bacteria are retained in a diverticulum. Signs of diverticulosis include cramplike pain in the left lower part of the abdomen, bowel irregularity, diarrhea, constipation, and thin stools. There may be some intermittent rectal bleeding with diverticulitis.

Inflammatory bowel disease (IBD) of unknown cause is most common in whites (usually female) between the ages of fifteen and thirty-five, occurring most frequently in the American Jewish population. The two types of IBD are Crohn’s disease, which is also known as regional enteritis, and ulcerative colitis. The disorders are considered to be separate diseases with similar characteristics.

Crohn’s disease may affect any part of the intestinal tract but often affects the small intestine. The inflammation usually involves the entire thickness of the intestinal wall. Treatment for Crohn’s disease depends on the presence or absence of symptoms. If there are no symptoms, treatment is not necessary. If there is evidence of inflammation, however, anti-inflammatory medication may be prescribed. Vitamin and mineral replacement may be given because of the problems of absorption associated with this disease. Surgery may be required at some point in the disease process because of its associated complications, such as obstruction.

Ulcerative
colitis is characterized by tiny ulcers and abscesses in the inner lining of the colon, where it is usually confined. There is a tendency for these ulcerations to bleed, causing bloody diarrhea. The chronic nature of inflammatory bowel disease may cause a stricture, which can result in an obstruction requiring surgical intervention. As with Crohn’s disease, the treatment for ulcerative colitis depends on the type of symptoms and may consist of medication, nutrition, or surgery. Anti-inflammatory drugs are used for flare-ups of the disease. Liquid food supplements may be given to compensate for nutrients lost in diarrhea. Intravenous therapy may be prescribed if the colon is considered too diseased to tolerate food.

There are many types of infections that affect the intestinal tract. The most common bacterial infections are caused by microorganisms such as
Salmonella and Shigella. Salmonella bacteria are commonly found in meats, fruits (through contaminated fertilizer), poultry, eggs, dairy products, and contaminated marijuana. Pet turtles are also a source of this bacteria. The source of Shigella bacterial infection is feces from an infected person, with the route of transmission being oral-fecal—for example, changing the soiled diaper of an infant or having a bowel movement and then eating or preparing food without properly washing one's hands.

Intestinal parasites may also cause infection. The most common of these parasites, Giardia lamblia, is present where water supplies are contaminated by raw sewage. The primary treatment for these conditions is replacement of lost fluids and essential electrolytes. Antidiarrheal medications may be prescribed, although they are not normally used because they may interfere with the elimination of the causative agent.

Intestinal obstruction occurs when the normal flow of the intestine is partially or totally impeded due to an accumulation of contents, gas, or fluid. It may also be caused by the intestine’s inability to propel contents along the intestinal tract, a process called
peristalsis. Peristalsis may be obstructed by scars that bind together two normally separate anatomic surfaces (adhesions), hernias, or tumors. Another cause may be paralytic ileus, a paralysis of the peristaltic movement of the intestinal tract, caused by the effect of trauma or toxins on the nerve endings that regulate intestinal movement. Conservative treatment consists of decompression of the bowel using a nasogastric tube. Surgical treatment may be indicated if the bowel is completely obstructed.

While tumors of the small intestine are rare, those of the colon are common.
Cancer of the colon and rectum is the second most common type of cancer in the United States (with lung cancer being the most common). The majority of intestinal tumors are benign (noncancerous) and discovered between the ages of forty and sixty. There are several types of benign tumors, which do not spread. They include lipomas, leiomyomas, angiomas, and adenomas. A small percentage of tumors of the small intestine are malignant (cancerous). The most common are adenocarcinomas, leiomyosarcomas, carcinoid tumors, and lymphomas. The symptoms of these tumors include weight loss, abdominal pain, nausea, vomiting, and bleeding. Treatment is dependent on the stage and location of the tumor. Surgical removal of the tumor may be coupled with chemotherapy or radiation therapy.

Polyps are benign tumors of the large intestine and are common in individuals over the age of sixty. They arise from the lining of the colon and are usually found during tests to diagnose other conditions. Polyps include several different varieties, the most common of which is a hyperplastic polyp. Hyperplastic polyps are less than one-half of a centimeter in diameter and do not pose a health risk. Juvenile polyps can occur in childhood, and inflammatory polyps are believed to result from injury or inflammation, such as after an episode of ulcerative colitis. Neither of these conditions poses a health risk. There is a major category of polyps known as adenomas, however, which have the potential for malignancy. These types of polyps are generally removed to prevent the development of cancer.

Rectal cancer and colon cancer
are common among both men and women. Factors that predispose an individual to these types of cancer include family history or a prior history of adenomatous colon polyps, colon cancer, or ulcerative colitis. The precise cause of these cancers is unknown, but diet is believed to play a significant role, specifically diets low in fiber and high in animal fat. One of the key symptoms of these conditions requiring immediate attention (especially for individuals over the age of forty) is rectal bleeding. Treatment consists of surgery to remove the affected part of the colon. The physician may prescribe additional treatment in the form of chemotherapy or radiation therapy.

Perspective and Prospects

Problems associated with the intestinal tract are characterized by a variety of symptoms and treatments. These problems may be temporary in nature or may be manifestations of more serious underlying conditions interfering with the normal functions of absorption, fluid and electrolyte balance, and elimination. Symptoms are signs of malfunction and should not be ignored or go untreated.

Preventing problems associated with the intestinal tract may not always be possible because the causes of some intestinal diseases and disorders are unknown. Nevertheless, there has been substantial research related to intestinal diseases and disorders to support a strong correlation between nutrition and intestinal tract health. For example, there is evidence to support the relationship between the consumption of sugars, high amounts of animal protein and fat, and cholesterol and cancer-causing agents in the intestinal tract. Stress and its resulting influence on stomach acidity also contribute to intestinal ill health. Smoking and lack of regular exercise may also negatively influence normal peristalsis.

The prevention of these and other problems related to intestinal health is important not only to general health but also to work productivity. In the United States, for example, intestinal problems account for a large percentage of lost work time. Education about intestinal health and health issues beginning early in one’s life will lower the incidence of some of the more common intestinal diseases and disorders.

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