The applied physiology of cough.

The cough reflex is such an important defense mechanism of the respiratory tract that a thorough knowledge of its applied physiology in respiratory disease is essential for clinicians. It is a well-integrated reflex, which has afferent limb consisting of receptors and afferent nerves, the central cough center in the brainstem and the efferent limb consisting of motor nerves supplying the muscles of coughing. The cough process consists of inspiratory phase, compressive phase and expiratory phase.