mucoasele

Mucoasele, in English mucous membranes, are moist protective linings that cover surfaces and cavities that communicate with the exterior of the body. They line the respiratory, digestive, urinary, and reproductive tracts, as well as parts of the oral and nasal cavities and the eyelids. Structurally, they consist of an epithelial layer, a supporting lamina propria (connective tissue), and, in many sites, a thin muscularis mucosae. The epithelial type varies by location: stratified squamous in the mouth, esophagus, and vaginal canal; simple columnar in much of the stomach and intestines; pseudostratified ciliated columnar in much of the respiratory tract; and transitional epithelium in the bladder. Goblet cells and glands secrete mucus, which keeps surfaces moist, traps particles, and helps protect against pathogens. The mucous layer also contains immune components such as secretory IgA, antimicrobial peptides, and resident immune cells.

Functions include protection from mechanical damage and pathogens, lubrication to ease movement of food and air, and participation in immune defense and selective absorption. Ciliated mucosa in the airways helps clear inhaled debris by moving mucus toward the pharynx. Maintaining hydration and a healthy mucus layer is important for barrier function; dryness, infection, or inflammation can disrupt the mucosa and predispose to disease.

Clinical relevance: mucosal infections (rhinitis, gastritis, enteritis), inflammatory mucosal diseases, and conditions such as xerostomia or chronic rhinitis. Mucosal routes are used for certain vaccines and drug delivery.

See also: mucosa; mucous secretion; mucosal immunity.