The cough reflex has both sensory and motor components. Pulmonary irritant receptors (cough receptors) in the epithelium of the respiratory tract are sensitive to both mechanical and chemical stimuli. Stimulation of the cough receptors by dust or other foreign particles produces a cough, which is necessary to remove the foreign material from the respiratory tract before it reaches the lungs. The cough receptors, or rapidly adapting irritant receptors are located mainly on the posterior wall of the trachea, pharynx, and at the main carina, the point where the trachea branches into the main bronchi...