Why do we cough and sneeze when we have a cold?

When we have a cold, the disease-causing germs reach the respiratory tract, and mucus builds in the bronchia. These are the branches of the air pipe that go inside the lungs. The body tries to get rid of this mucus by coughing vigorously and throwing the disease-causing germs out of the lungs along with air. The same thing happens when we sneeze. The nasal mucus is stimulated and the nose starts to tingle. We have to sneeze and in this case too, the germs are thrown outside forcefully.