Airway secretions and mucous glands

Airway secretions and mucous glands represent a complex physiological system essential for respiratory health and innate immunity. The primary function of this system is the production of mucus, a viscoelastic gel that traps inhaled particulates, allergens, and pathogens, facilitating their removal through mucociliary clearance (StatPearls, 2023). This mucus is primarily composed of water, ions, and large gel-forming glycoproteins known as mucins, specifically MUC5AC and MUC5B (PubMed, PMID: 29030104). Submucosal glands, located beneath the airway epithelium, and surface goblet cells are the principal sites of secretion, regulated largely by parasympathetic signaling via muscarinic M3 receptors (NIH, 2022). In chronic respiratory diseases like asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis, the system becomes dysfunctional, leading to mucus hypersecretion, increased viscosity, and impaired clearance, which contribute to airway obstruction and recurrent infections (PubMed, PMID: 30243718). Therapeutic strategies targeting this system include mucolytics to reduce viscosity, expectorants to enhance clearance, and anticholinergics to suppress glandular secretion (PubChem, 2024).

Other names

Bronchial secretionsTracheobronchial mucusAirway submucosal glandsRespiratory mucus

Pharmacological agents modulate this system through several pathways: mucolytics like acetylcysteine disrupt disulfide bonds in mucin polymers to decrease viscosity; expectorants like guaifenesin increase the volume of secretions to facilitate coughing; and muscarinic antagonists like ipratropium block cholinergic stimulation of submucosal glands to reduce total mucus output (StatPearls, 2023; PubChem, 2024).