人的生命活动需要不停地从外界环境中摄取氧气(O_2),供体内进行代谢,同时产生能量,并将代谢所产生的二氧化碳(CO_2)排放到外界环境中去。O_2的摄入和 CO_2的排出要经过肺泡与外界气体的交换(叫做通气)和肺泡与血液气体的交换(叫做换气)这两个过程,完成这两个过程要具备通畅的呼吸通道,包括鼻腔、咽、喉、气管(总称上呼吸道)、各级支气管、 Human life and activity need to constantly take in oxygen (O 2) from the external environment for metabolism in the body, while generating energy, and the metabolism of carbon dioxide (CO 2) emissions to the external environment. O 2 intake and CO 2 excretion through the alveolar exchange with the outside world gas (called ventilation) and the alveolar and blood gas exchange (called ventilation) of these two processes, the completion of these two processes to have a smooth breathing channel, including Nasal, pharynx, larynx, trachea (collectively, the upper respiratory tract), bronchus at all levels,