The digestive system performs the vital function of breaking down large particles of food into molecules that the body then uses for nourishment and energy. The entire digestive tract consists of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum and anus. Many diseases and disorders interfere with the process of digestion. Structural disorders involve an abnormality of the digestive system, while functional disorders interfere with normal function without the presence of any structural abnormality.
Irritable Bowel Syndrome
Irritable bowel syndrome, often called IBS, affects approximately 20 percent of the American population, making it the most common digestive disorder, according to the UCLA Center for Neurovisceral Science and Women's Health. Symptoms, which range from mild to severe, include frequent diarrhea, abdominal pain, gas, bloating and bowel urgency.
IBS is a function disorder of the lower digestive tract, affecting mostly the large intestine, also known as the colon. The colon functions to absorb water and salts while moving the remaining wastes toward the rectum through a series of muscle contraction controlled by nerves, hormones and electrical impulses. Because those with IBS have no structural abnormality, it is a functional disorder that responds to emotional conflict and stress.
Dyspepsia
Dyspepsia, upper abdominal pain and discomfort, is considered functional when is occurs in the absence of another systemic or metabolic disease. Although dyspepsia and IBS often occur together, dyspepsia can occur on its own, according to the Mayo Clinic. Possible causes of dyspepsia include increased acid production, delayed stomach emptying, abnormal responses to food, or poor circulation between the upper and lower parts of the stomach.
Gastroesophageal Reflux Disease
Gastroesophageal reflux disease, called GERD for short, occurs when the lower esophageal sphincter---a ring of muscle between the esophagus and the stomach---fails to function properly. GERD occurs when the lower esophageal sphincter fails to close completely or opens spontaneously, allowing stomach acid to rise into the esophagus. The symptoms include a burning sensation in the chest often referred to as heartburn or acid indigestion, difficulty swallowing, chronic cough and asthma-like symptoms, according to the National Digestive Diseases Information Clearinghouse.
Chronic Constipation
Chronic constipation is a functional digestive disorder characterized by either the difficulty in passing stools or infrequently---defined as fewer than three times a week---passing stools. Chronic constipation often occurs as a result of an inadequate diet. Although rarely a sign of a more serious condition, chronic constipation causes fissures, or tiny tears, or hemorrhoids around the anus.
