Not only the Western medical science, but also the traditional Chinese medical science, they are cognizant that lungs are respiratory organs. Our ancestors also found some physiological phenomena of pulmonary circulation.
The active substance of lungs is called “lung-Qi” (肺气). The basic functions of lung-Qi are raising (宣发) and downward purging (肃降). The functions of lungs derive from the two basic functions of lung-Qi.
The first important function of lungs is to control Qi (气) and respiration. Qi is a wide concept. Qi in lungs includes air, lung-Qi and Zong-Qi (宗气). Air is from the nature. Because of the function of raising of lung-Qi, waste and foul air is expelled from lungs. Because of the function of downward purging of lung-Qi, fresh air is inhaled into lungs. If the functions of raising and downward purging work harmoniously, the respiration is balanced and unobstructed. But if lung-Qi is deficient, its two functions won’t be harmonious, and one of them or both of them will be weakened, and then the person will cough or even pant. The main pathological cause of bronchitis, asthma and emphysema is the deficiency of lung-Qi and the disturbance of lung-Qi’s functions.
Zong-Qi is formed in lungs by natural air and nutrient substances which are from food. Zong-Qi is different from lung-Qi, because lung-Qi is only in lungs, but Zong-Qi can run in the whole body, and Zong-Qi always promote the functions of lung-Qi. Zong-Qi is the basic substance which is the motive power of many physiological processes. It enhances lungs to respire and promotes the heart to impulse blood, and also can nourish the Original Qi (元气) which is the basic vital energy of a body. If lung-Qi is deficient, the lung-Qi’s functions of raising and downward purging will be weakened and lose balance, the respiration will be disturbed, and the formation of Zong-Qi will also be reduced, and then the functioning of heart will be impaired.
The second important function of lungs is to promote water metabolism of a body. The promoting of water metabolism is via the lung-Qi’s functions of raising and downward purging. The function of raising promotes water and nutrient substances to be carried upwards to the head and to be carried outwards to the muscles and skin of the whole body. The function of downward purging promotes water and nutrient substances to be carried downwards to other internal organs and also promotes foul and waste water to be carried to kidneys and form urine. The disturbance and weakness of the function of promoting water metabolism can cause edemas.
The third important function of lungs is to promote gas exchange and blood circulation. It shows ancient Chinese had found some physiological phenomena of pulmonary circulation. This function derives from the lung-Qi’s basic functions of raising and downward purging and the Zong-Qi’s function of promoting the heart to impulse blood. As the fourth paragraph says, if lung-Qi is deficient, the formation of Zong-Qi will be reduced, and not only gas exchange but also blood circulation will be disturbed and even obstructed, and then there will be chest distress, palpitation and blood stasis. Conversely, in many heart diseases, the heart-Qi which is the motivity of a heart is deficient, and the blood circulation is obstructed, the lung-Qi’s functions of raising and downward purging also will be impaired, and there will be cough and pant. So we can see, severe pulmonary diseases and heart diseases are always related to each other.
A nose is the only channel for expelling and inhaling air. So the nose is called “the passage of lungs”. The olfaction of the nose depends on the lung-Qi’s function of raising. If the function of raising of lung-Qi is obstructed, the nose will be stuffed and the respiration will be affected badly. If pathogenic heat harms lungs, the nasal mucus will be yellow and thick. If pathogenic cold harms lungs, the nasal mucus will be pellucid and watery. If pathogenic dryness harms lungs, the nasal mucus will be few. So the nasal mucus is called “the liquid of lungs”, though nasal mucus is excreted by the nose. The abnormal phenomenon of the nose’s functioning is always one of the important clinical features for diagnosing the pathological changes of lungs.
Moreover, according to the theory of the traditional Chinese medical science, the feelings of sadness and melancholy are related to lungs. Excessive sadness and melancholy can impair lung-Qi and even cause the shortness of breath. The deficiency of lung-Qi can cause the feelings of sadness and melancholy. It also gives much enlightenment for the treatment of some mental diseases.