Digestive system disease

 digestive system disease, any of the diseases that affect the human digestive tract. Such disorders may affect the esophagus, stomach, small intestine, large intestine (colon), pancreas, liver, or biliary tract. A prevalent disorder of the digestive system is gastroesophageal reflux disease (i.e., the passage of gastric contents into the esophagus), which causes heartburn on a regular basis in some individuals. Cirrhosis of the liver primarily results from excessive alcohol consumption, but it may also develop after infection with the hepatitis C virus. Other common diseases of the digestive system include peptic ulcers, colorectal cancer, and gallstones. Many disorders of the digestive system can be prevented by a diet low in fats and high in fruits and vegetables, limited alcohol consumption, and periodic medical examinations.

This article discusses the common infections, inflammations, ulcers, and cancers that affect each organ of the digestive tract. For a detailed discussion of the anatomy and physiology of the digestive system, see digestive system, human.

Mouth and oral cavity

Besides local disease, features characteristic of systemic disorders are often present on the mouth and in the oral cavity. The lips may be fissured and eroded at the corners in riboflavin deficiency. Multiple brown freckles on the lips associated with polyps in the small intestine is characteristic of Peutz-Jeghers syndrome. Aggregates of small yellow spots on the buccal mucosa and the mucosa behind the lips due to the presence of enlarged sebaceous glands just below the mucosal surface indicate Fordyce disease.

Dental caries

Dental caries, or cavities, are due to the destruction of the dental enamel and underlying tissues by organic acids. These acids are formed by bacteria growing in debris and food accumulated in pockets between the base of the teeth and the gum margins. Poor oral hygiene is the underlying predisposing circumstance.

Pharyngitis

Inflammation of the posterior wall of the mouth and of the tonsils and adjoining tissue on each side of the oral pharynx is very common, especially in young persons. Such infections are due to bacteria of the streptococcal and staphylococcal species or from viral infections. In viral pharyngitis the tissue is usually less red and swollen than is true of streptococcal pharyngitis, and it is less often covered by a whitish exudate (protein-rich fluid). Other tonsillar tissue in the upper part of the pharynx and at the root of the tongue may be similarly involved. In diphtheritic pharyngitis, the membranous exudate is more diffuse than in other types of pharyngitis, it is tougher, and it extends over a much larger part of the mucous membrane of the mouth and nose.

Stomach

Indigestion

Indigestion, also called dyspepsia, is any or all of the unpleasant symptoms that are associated with the malfunctioning of the digestive system. Indigestion may be caused by a disease, but it primarily occurs because of stress or improper eating habits, smoking, drinking excessive quantities of coffee or alcohol.

Ulcerative diseases

Ulcers are produced when external factors reduce the ability of the mucosal lining to resist the acidic effects of gastric juice (a mixture of digestive enzymes and hydrochloric acid).

Crohn disease

Crohn disease is characterized by chronic inflammation of the digestive tract, usually the terminal portion of the small intestine. The cause of Crohn disease is unknown. Apart from the greater tendency for fistulas to form and for the wall of the intestine to thicken until the channel is obstructed, it is only distinguishable from ulcerative colitis by microscopic findings. In Crohn disease, the maximum damage occurs beneath the mucosa, and lymphoid conglomerations, known as granulomata, are formed in the submucosa. Crohn disease attacks the perianal tissues more often than does ulcerative colitis. Although Crohn disease and ulcerative colitis are not common, they are disabling.