Bronchial mucous glands and airway mucus

Bronchial mucous glands and airway mucus constitute a critical component of the respiratory system's innate defense mechanism, known as the mucociliary escalator (StatPearls: Physiology, Mucociliary Clearance). The submucosal glands, located primarily in the cartilaginous airways, secrete a complex mixture of water, ions, and glycoproteins (mucins) that form the airway surface liquid (PubMed: PMC6016586). This mucus layer traps inhaled particulates, pathogens, and toxins, which are then transported out of the lungs by ciliary beating (NIH: How the Lungs Work). In pathological states such as asthma, COPD, and cystic fibrosis, mucus production can become excessive or its rheological properties can be altered, leading to airway obstruction and increased infection risk (PubMed: 30243719). Pharmacological intervention typically aims to either reduce mucus hypersecretion through anticholinergics or modify the physical properties of the mucus using mucolytics and expectorants to facilitate clearance (StatPearls: Mucolytics). Specific molecular components within this system, such as MUC5AC and MUC5B mucins, are often the focus of research into targeted therapies for muco-obstructive lung diseases (PubMed: 29097370). Effective management of airway mucus is essential for maintaining lung function and preventing secondary bacterial infections in chronic respiratory conditions (PubMed: 31513778).

Other names

Airway surface liquidBronchial secretionsSubmucosal glandsRespiratory mucusTracheobronchial secretions

Drugs targeting this system act via several mechanisms: mucolytics (e.g., acetylcysteine) break disulfide bonds in mucin polymers to reduce viscosity; expectorants (e.g., guaifenesin) increase the volume and reduce the adhesiveness of secretions; and anticholinergics (e.g., ipratropium) inhibit muscarinic receptors on submucosal glands to decrease mucus production.