Coughs are very common, and can be caused by a variety of triggers. A cough is a reflex response that aims to clear the airway of irritants, and several parts of the body are involved in the cough action.

Cough receptors are located in the walls of the airways and are triggered by irritants such as smoke, microorganisms or conditions such as asthma. The receptors trigger an impulse that runs along the vagus nerve to the cough centre, which is located in the medulla oblongata of the brain.

This in turn sends nerve impulses to the respiratory muscles, causing a sudden inhalation of air. This air becomes momentarily trapped in the lungs due to closure of the glottis and vocal cords in the throat.

The intercostal muscles between the ribs, the abdominal muscles and the diaphragm then contract and force air out through the re-opened glottis. The pressure of the air forces the glottis and vocal cords to open. The pressure of the air as it leaves the body, hopefully taking with it the original airway irritant, causes the sensation €“ and characteristic noise €“ known as a cough.