The lungs are located in the thoracic cavity, above the diaphragm and on either side of the mediastinum.1. The lungs are located in the thoracic cavity, between the clavicle and the abdomen. Using the sternum as a dividing line, there is a lung in each of the right and left lateral thoracic cavities. Above the clavicle is the upper end of the lungs, called the apices. The lower part of the lung is between the lowermost ribs and the abdomen and is called the base of the lung. The central depressions of the right and left lungs are the hilums, and in the middle of the lungs are the large blood vessels and the heart. The lungs have a total of five lobes, namely the left lung has two lobes and the right lung has three lobes. The two lungs are different in shape, with the right lung being wide and short and the left lung being narrow and long. Inhaling oxygen and expelling carbon dioxide, this gas exchange is the most important function of the lungs. Lungs have a wide breathing area, in the breathing process, the external environment of organic or inorganic dust, including a variety of microorganisms, protein allergens, harmful gases, etc., can enter the respiratory tract and lungs caused by a variety of diseases, and thus the respiratory system’s defense function is crucial.