Bronchialsekretion

Bronchialsekretion is the mucus and serous secretions produced by the respiratory epithelium of the conducting airways. It is generated mainly by goblet cells and by submucosal glands in the trachea and bronchi. The secretion contains water, mucins (notably MUC5AC and MUC5B), electrolytes, antimicrobial proteins such as lysozyme and lactoferrin, secretory IgA, and various immune cells when inflammation is present.

Functions of bronchial secretions include moisturizing and protecting the airways, trapping inhaled particles, and supporting mucociliary clearance. The ciliated epithelium moves secretions toward the pharynx for swallowing or expectoration, helping to prevent infection and maintain airway patency.

Regulation of secretion is influenced by neural and chemical mediators. Parasympathetic activity and acetylcholine can increase glandular and goblet cell secretion. Inflammatory conditions such as asthma, chronic bronchitis, and chronic obstructive pulmonary disease can cause goblet cell hyperplasia and an overall increase in mucus production, often accompanied by changes in mucus viscosity and composition.

Clinical relevance: changes in bronchial secretion are common in many respiratory diseases. Excessive or thick secretions can contribute to coughing, dyspnea, and airway obstruction. Infections may render sputum purulent. Diagnosis can involve sputum collection for cytology, microbiology, and inflammatory markers. In cystic fibrosis, secretions are particularly viscous due to ion transport defects, leading to impaired clearance. Treatment focuses on hydration, mucolytic agents, bronchodilators, anti-inflammatory therapy, and airway clearance techniques to improve mucus expectoration.