Physiological Characteristics of the Lung
The physiological characteristics of the lung may be summarized as the following
three aspects
1) As a"Florid Canopy"
The lung is known as "florid canopy", communicating directly with the outside
world. The lung is one of the five zang-viscera, pertaining to the interior. It, however, differs from the four zang-viscera in that it is not only situated in the thorax cavity, occupying the topmost position among the five zang-viscera, and known as the appellation of "florid canopy"; but it also communicates with the natural world through the throat and nose. Wind, cold, dryness, heat evils in the natural world, especially warm-heat evilqi,mostly attack the lung via the mouth and nose. This leads to the pathological changes and failure of lung-qi and defense-qi in dispersion as well as the dysfunction of opening of the lung.
2) Being a"Delicate Organ"
The lung is a "delicate organ" and has aversion to cold and heat evils. The causes of this come from two aspects: On one hand, the lung is a clear and empty organ which
opens into the nose, corresponding to the skin and hair. This allows for the exogenous
evil-qi to directly attack the lung, leading to lung dysfunction. On the other hand, the lung is the "florid canopy" of the five zang-viscera, and the evil-qi due to the pathological changes of other viscera, frequently fumigates the lung. This is characterized by cough and asthma etc. Thus, Chapter 38 in the Plain Questions states: "Each of the five zangviscera and six fu-viscera may lead to cough, not the lung only. " Although the lung pertains to metal in the five element theory, it however is not as unyielding as liver-wood.Cold evil damages the yang-qi of the lung, while heat evil consumes yin-fluid of the lung,thus resulting in various pathological changes of the lung.
3) Correspondence to Autumn
Lung-qi flourishes in the autumn according to the theory of "correspondence between man and nature. " Since the lung derives supplement from the natural world, the lung disorder may improve in the autumn, and the patient may feel more comfortable. It is certain that excessive dry weather in the autumn may consume yin-fluid of the lung, giving rise to a dry cough with scanty sputum, chapped skin, dryness of the nose and throat, etc.
