Cough reflex

The cough reflex is a coordinated response that expels irritants, foreign material, and secretions from the airways through a forceful burst of airflow.

Airway sensory receptors: Nerve endings in the airways detect mechanical, chemical, and inflammatory stimuli. These receptors detect irritants that initiate the cough reflex.
Respiratory tract: The connected airways that conduct air between the atmosphere and the lungs. The cough reflex protects this passage from obstruction and contamination.
Cough: A forceful expiration, often reflexive, that clears material from the airways. The cough reflex is the neural mechanism behind many coughs.
Sneeze reflex: A reflex that expels irritants from the nasal passages through a sudden burst of air. It shares an expulsive pattern with coughing but begins chiefly in nasal pathways.
Vagus nerve: A cranial nerve carrying sensory and motor signals between the brain and organs including the lungs. Sensory cough signals travel centrally through vagal pathways.
Larynx: The organ connecting the pharynx and trachea that contains the vocal folds. It closes and reopens during the pressure-building and expulsion phases.
Chronic cough: A cough lasting longer than the duration thresholds used in clinical guidelines, commonly eight weeks in adults. Persistent coughing can signal ongoing activation or heightened sensitivity of the reflex.
Gag reflex: A protective reflex that contracts the throat muscles in response to stimulation of the pharynx. It protects the upper digestive passage rather than clearing the lower airways.
Medulla oblongata: The lower part of the brainstem, which contains centers coordinating vital autonomic functions. Brainstem networks organize the respiratory pattern of coughing.
Trachea: The cartilage-supported airway that carries air from the larynx to the bronchi. Its sensory lining can trigger coughing when irritated.

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