The cough is a contraction spasmodic sudden and often repetitively, the human thoracic cavity, which causes a violent expulsion of air from the lungs, and usually accompanied by a distinctive sound. The cough is usually initiated to get rid of an accumulation of mucus in the airways, the air can move through this transition to a speed of 480 km / h. The cough can also be induced by a bolus of food entering the trachea instead of the esophagus by a deficiency of the epiglottis. A frequent cough or chronic typically indicates the presence of a disease.
The cough is to block the flow of air into the airway by voluntary closure of the glottis, then to increase intra-thoracic pressure by contraction of respiratory muscles. This increases the pressure of air trapped in the airways. It follows a sudden release of obstruction, which allows expulsion of air at high speed because of this pressure, carrying with it the elements may be present in the airways.
The droplets are of cough and the sneeze factor of contagion. It protects the environment of germs pathogenic coughing cons his arm and not his hand, which is an important vector of infection.