MECHANISM OF COUGH
The mechanism of the cough includes:
(1) A deep initial inspiration;
(2) The tight closure of the glottis and it is reinforced by the supra glottic structures;
(3) The contraction of the expiratory muscles;
(4) The sudden opening of the glottis while the contraction of the expiratory muscles continues.
In the last two phases of the mechanism, the very high intrapulmonary pressure is generated so that the rapid airflow from the lungs is formed and it opens the glottis. Along with it, the pressure difference forms between outside and inside the intra thoracic airways. This causes their dynamic compression and narrowing. This air flow and the airway narrowing cause the expulsion of the air stream. Its linear velocity sometimes reaches the speed of sound. This air flow expels the secretion in the trachea with a great force. The combination of a high airflow and airway narrowing results in the expulsion of an air stream with a linear velocity sometimes nearing the speed of sound. The blast of air thus produced is capable of expelling the secretions with a great force.
Tags: Cough, Sputum Formation,Rapid air flow from lungs, glottis open cough.