The path from mouth and nose to lungs might seem simple, but it is actually full of many more parts. One such part is called the epiglottis. The epiglottis is a flap that covers the entrance to the top of the tube that leads to the lungs, the trachea, when you swallow. The trachea is lined with tiny hairs called Cilia, and mucus. Cilia help remove dust and other things from the air, and mucus, found in the nasal passages and sinuses, warms and moistens the air, while also helping trap dust particles. Mucus also protects mucous membranes, which is a type of tissue that lines body cavities and creates more mucus. Once the air goes past the epiglottis and trachea, and cleaned by the cilia and mucus, it travels through two tubes called the bronchi.