The difference between the upper and lower respiratory tracts is that the upper respiratory tract is above the cricoid cartilage and mainly warms, filters and humidifies gases; the lower respiratory tract is below the cricoid cartilage and mainly exchanges gases with the capillary network in the lungs.
The complete respiratory tract refers to the whole section from the nasal cavity to the lungs, and the respiratory tract is divided into upper and lower respiratory tracts with the cricoid cartilage as the dividing line. The two have different locations and contain different organs. The upper respiratory tract mainly includes the nasal cavity, pharyngeal cavity, larynx and so on. The lower respiratory tract includes the trachea, bronchi, and all levels of branching bronchi, alveoli and so on.
The upper respiratory tract has the role of wetting the airway, can moisten the inhaled air, filtering impurities in the air, to prevent the production of respiratory diseases, upper respiratory tract infections to pharyngolaryngitis, tonsillitis and other common.
Lower respiratory tract in addition to maintaining ventilation and respiratory function, but also to maintain the human body ventilation function. The human body ventilation function depends on the contraction and expansion of the lungs, in the lower respiratory tract function infection may cause bronchitis, pneumonia and other diseases.