Digestive diseases refer to diseases along the gastrointestinal tract from the mouth to the end of the system and includes several other organs such as the liver, gallbladder, biliary tree and pancreas. There are many causes of digestive diseases. One specific type of digestive problem, which is not really a disease but a food intolerance, is lactose intolerance.
Genetic Differences and Changes
Genes are sequences of DNA that code for the construction of proteins. Proteins serve many functions in the body, such as support structures, hormones and transporters of molecules. Diffferent sequences of genes code for different proteins, and some may be more or less effective. In addition, genes can be turned on or off by the body throughout life.
Lactose is a sugar common in dairy products that is broken down by the enzyme lactase. Normally the enzyme is not made in the body after about age four, and most people are actually lactose intolerant. However, some people have a mutation that prevents this. These people do not become lactose intolerant. Very rarely, a person may have a genetic difference that prevents the normal production or function of lactase; these people will be lactose intolerant from birth.
Immune System Dysfunction
Immune system dysfunction is another cause of many digestive disorders. The exact mechanisms, or in other words what causes the immune system to attack the digestive organs, is an area of active research. Common examples include Crohn's disease, in which inflammatory lesions can develop anywhere in the digestive tract, and ulcerative colitis, characterized by an inflamed colon.
Infection
Many different types of infections can cause digestive disorders. Viral, bacterial, fungal and protozoan infections are responsible for many diseases of the digestive tract. Bacteria may directly damage and invade the walls of the GI tract or produce toxins that make you sick. Many viruses also cause GI disease, such as the Norwalk virus that frequently causes outbreaks of GI distress on cruiseships. Protozoal infections are more common in developing nations and those with suppressed immune systems.
Tumors
Tumors, benign or cancerous, can cause disease of the digestive system. These are less frequent causes than those above. Cancers of the mouth, esophagus, stomach, pancreas, liver and colon continue to cause significant disease, however. These cancers are generally easiest to treat when caught early and cause more problems when they spread from their origin of growth. The causes of many of these cancers are unknown, but genetics and environmental factors such as tobacco both make contributions.
Further Systemic Problems
Further problems to other systems in the body can contribute to significant disease in the GI tract. Vascular diseases can restrict blood flow to the GI tract or lead to inflammation. Trauma and ingested toxins and drugs can directly damage the tissues or change its function. Congenital problems can lead to organs being formed improperly or in the wrong location.
References
- "Robbins and Cotran Pathologic Basis of Disease, 8th Ed."; Vinay Kumar et al; 2009
- "Harrison's Principles of Internal Medicine, 17th Ed."; Anthony S Fauci et al; 2008
