Is a slimy, viscous substance produced by mucus glands in mucous membranes. It forms a thin protective film over the underlying epithelium acting as a lubricant and helps prevent drying of the damage to the surface layers of the mucous membrane.  Mucus is composed chiefly of large protein molecules called mucins and inorganic salts suspended in water. The mucus in the nose and air passages also captures small inhaled particles of dust, pollutants and irritants. The mucus is wafted backwards through the nose or upwards from the lungs into the throat where it is swallowed. Although the vocal folds are lubricated by mucus, this comes from other areas within the larynx as the vocal folds themsleves do not have any mucus gland themselves.