Lung is the source of water god, and kidney is the main source of water: lung governs the qi of the whole body, and water can only reach all tissues and organs of the whole body through the spread and decline of lung qi, and then be transported to the bladder, so it is called "lung is the source of water god". Kidney yang is the basis of all yang in human body, and its gasification has the function of ascending and descending water and liquid. The lungs and kidneys cooperate with each other to complete normal water and fluid metabolism. Lung and kidney play an important role in regulating water and liquid metabolism, so there is a saying that "it is in the kidney and its mark is in the lung"

The lung governs qi, and the kidney is the root of qi: the lung is responsible for breathing and the kidney is responsible for receiving qi. Although breathing is the master of the lung, it needs the help of the kidney to receive qi. Only when the essence of the kidney is abundant and the inhaled gas passes through the lungs can it be attributed to the kidney, and the lungs and kidneys cooperate with each other to complete the physiological activities of breathing.

(2) Pathology

The lung is blocked, the waterway can't be opened, the kidney can't control the water, the water evil overflows, and the interaction between lung and kidney leads to the disorder of water and liquid metabolism. Although the disorder of water-liquid metabolism is related to the lung, it is still in the kidney, so "water disease is characterized by abdominal distension in the lower month and wheezing in the upper month, and all specimens are sick", "its source is in the kidney and its end is in the lung". Because lung, spleen and kidney are interrelated, influence each other and play different roles in the process of regulating water-liquid metabolism, the key to treat water-liquid metabolic diseases is to take kidney as the foundation, lung as the standard and spleen as the main factor.

If the kidney qi is insufficient, it has no right to absorb, and the qi floats on the body; Long-term deficiency of lung qi, injury of kidney qi and loss of absorption function of kidney will lead to shortness of breath, shortness of breath, excessive breathing and less inspiration, especially during exercise. This phenomenon is called "kidney does not accept qi" or "qi does not return to its origin". Its treatment must also use the method of tonifying kidney and absorbing qi.

In addition, lung and kidney yin fluid are also mutually nourishing (called golden water), and kidney yin is the basis of all yin in human body, so lung yin deficiency can damage kidney yin; Deficiency of kidney yin can not nourish lung yin, so lung yin is also insufficient, which eventually leads to deficiency of lung and kidney yin, resulting in soreness of waist and knees, hot flashes, night sweats, dry throat, red cheekbones, dry cough, hoarseness, nocturnal emission in men, amenorrhea in women and other symptoms. If it is a patient with tuberculosis and cough and asthma, symptoms of deficiency of both lung and kidney may appear after long-term illness.