This typically clears particles from the bronchi and trachea, the tubes that feed air to lung tissue from the nose and mouth.
Cough receptors in the surface cells (epithelium) of the respiratory tract are also sensitive to chemicals.
The efferent neural pathway then follows, with relevant signals transmitted back from the cerebral cortex and medulla via the vagus and superior laryngeal nerves to the glottis, external intercostals, diaphragm, and other major inspiratory and expiratory muscles.
[2][3] Weakness of the respiratory muscles, tracheostomy, or vocal cord pathology (including paralysis or anesthesia) may prevent effective clearing of the airways.
The cough reflux as a result of irritants, can be tested by inhaling air with nebulized 200 μmol/L capsaicin.