The most important function of the lungs is gas exchange. In addition, the lungs also have the functions of defense, metabolism and immunity. 1. Gas exchange function: the main function of the lungs is to send fresh oxygen into the bloodstream to the organs of the whole body, and to expel the carbon dioxide and other exhaust gases produced by the body. 2. Defense function: It has the function of removing pathogenic microorganisms and particulate dust in inhaled gas, and keeping the trachea and bronchial tubes sterile. 3. Metabolic and immune functions: the lungs can secrete interferon, complement and other biologically active substances to regulate their own and other organs’ functional activities. In addition to the above, the lungs also have functions such as blood storage. If there is any lung abnormality, it is recommended to consult a doctor in time, follow the doctor’s instructions for further examination, clarify the cause with the doctor’s help, and carry out targeted treatment or therapy.