MUC5B is a polymeric protein secreted from submucosal glands and some goblet cells, and this is in the form of strands. MUC5AC is the main gel-forming mucin secreted by goblet cells, in the form of threads and thin sheets. The major mucins secreted – MUC5AC and MUC5B - are large polymers that give the mucus its rheologic or viscoelastic properties. Mucus is made up of a fluid component of around 95% water, the mucin secretions from the goblet cells, and the submucosal glands (2–3% glycoproteins), proteoglycans (0.1–0.5%), lipids (0.3–0.5%), proteins, and DNA. The mucus blanket aids in the protection of the lungs by trapping foreign particles before they enter them, in particular through the nose during normal breathing. The periciliary liquid layer surrounding the cilia consists of a gel meshwork of cell-tethered mucins and polysaccharides. The periciliary liquid layer is so named as it surrounds the cilia and lies on top of the surface epithelium. The airway surface liquid consists of a sol layer termed the periciliary liquid layer and an overlying gel layer termed the mucus layer. In the human respiratory system, mucus is part of the airway surface liquid (ASL), also known as epithelial lining fluid (ELF), that lines most of the respiratory tract. Respiratory system įurther information: Mucociliary clearance Illustration depicting the movement of mucus in the respiratory tract Plants produce a similar substance called mucilage that is also produced by some microorganisms. Most of the mucus in the body is produced in the gastrointestinal tract.Īmphibians, fish, snails, slugs, and some other invertebrates also produce external mucus from their epidermis as protection against pathogens, and to help in movement and is also produced in fish to line their gills. Mucus serves to protect epithelial cells in the linings of the respiratory, digestive, and urogenital systems, and structures in the visual and auditory systems from pathogenic fungi, bacteria and viruses. It is a viscous colloid containing inorganic salts, antimicrobial enzymes (such as lysozymes), immunoglobulins (especially IgA), and glycoproteins such as lactoferrin and mucins, which are produced by goblet cells in the mucous membranes and submucosal glands. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. Mucus ( / ˈ m j uː k ə s/ MEW-kəs) is a slippery aqueous secretion produced by, and covering, mucous membranes. Mucous cells of the stomach lining secrete mucus (pink) into the lumen For other uses, see Mucus (disambiguation).
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