Mucus, goblet cell, submucosal gland

Abstract

Airway mucus blankets all mucosal surfaces, providing a physicochemical barrier that protects underlying epithelium against bacteria, viruses, and inhaled particles and gases. Mucus maintains airway hydration and plays an important role in the innate immune system by trapping foreign and endogenous substances, facilitating clearance by mucociliary activity. Mucus also has antioxidant, antiprotease, and antimicrobial functions. Composed of water, ions, serum protein exudates, epithelial secretions, and glandular and goblet cell products, mucus contains various defensive components such as glycoproteins (mucins), antibodies, defensin, lysozyme, and lactoferrin.