Mucin

A secretion containing carbohydrate-rich glycoproteins produced by mucous membrane. Mucins are sythesized and secreted by the epithelial cells of gastrointestinal, respiratory and genitourinary tract. Mucin plays an important role in the normal functioning of the airways and in the various obstructive airway diseases (asthma, cystic fibrosis, bronchiectasis and chronic bronchitis). It acts as a protective agent in many vital organs of the body. For example, in gallbladder, mucin functions as a protective agent against toxic bile acids. In the intestine, insufficient production of mucin may cause inflammatory bowel disease. Dry eye conditions are associated with reduced tear film mucin as well as alterations and mucin composition and distribution.