Mukus

Mukus, commonly spelled mucus in English, refers to the slippery, gel-like secretion produced by mucous membranes and certain glands in many animals, including humans. In humans it lines and protects the respiratory, gastrointestinal, and genitourinary tracts, as well as the ocular surface and oral cavity.

Composition and properties: Mukus is mainly water, with mucins—large glycoproteins that give it its viscous, sticky quality—along with salts, lipids, enzymes, and antibodies such as secretory IgA. The precise composition and viscosity vary by tissue and physiological state, allowing mukus to moisturize surfaces while trapping particles and microbes.

Functions: The primary roles of mukus are lubrication and protection of mucosal surfaces, trapping dust, microbes, and irritants, and facilitating removal through mucociliary clearance in the airways. In the digestive tract, mukus helps cushion and protect the mucosa; it also contributes to the stability of the tear film and overall ocular surface health.

Production and regulation: Mukus is produced by goblet cells in the epithelium and by submucosal glands. The rate and viscosity of production are influenced by hydration, irritation, infection, and inflammatory conditions. Infections or allergic responses often raise mucus production and can thicken its consistency.

Clinical notes: Abnormal mucus production or altered viscosity is associated with a range of conditions, including infections, allergies, asthma, chronic obstructive pulmonary disease, and cystic fibrosis. Color or texture changes can reflect underlying processes but are not by themselves diagnostic.

Linguistic note: In Turkish and some other languages, the term mukus refers to the same substance described here. See also mucous membranes, mucociliary clearance, and goblet cells.