The respiratory tract serves to add warmth and moisture to inhaled air, and it protects the respiratory tract by purifying the air of impurities. The respiratory tract consists of the nose, throat, larynx, trachea, bronchial tubes and lungs. The mucous membrane of the respiratory tract is rich in blood supply, so it can add warmth and humidity to the inhaled air. The mucus and plasma secreted by the mucous membrane of the respiratory tract can adhere to larger dust or particles in the air and expel them from the body. The respiratory tract is covered with pseudo-complex or monolayer ciliated columnar epithelium, with the wall of the cup-shaped cells and mucus glands secrete mucus together constitute mucus – ciliated drainage system, with the air into the dust particles, by the cilia swinging from the bottom upward drainage, until the cough and be cleared. If you have respiratory symptoms, you need to go to the hospital as soon as possible, by the doctor according to the specific conditions, to develop individualized diagnosis and treatment plan, so as not to delay the condition.