Final answer:
Coughing is an involuntary response of the respiratory system that helps to remove mucus and debris from the upper respiratory tract to the mouth.
Step-by-step explanation:
The material that moves up the mucociliary escalator to the throat is generally removed from the respiratory tract by clearing the throat or coughing. Coughing is a largely involuntary response of the respiratory system that occurs when nerves lining the airways are irritated. It helps to remove mucus and debris from the upper respiratory tract to the mouth. The mucus may be expectorated or swallowed and destroyed by stomach acids.