① Explain the physiological characteristics of the five internal organs. For example, the liver is "wood" because it has the function of stopping diarrhea and has no hair growth characteristics. Heart yang has the function of warming, and fire has the characteristics of yang heat, so heart belongs to "fire"; Spleen is the source of biochemistry and soil has the characteristics of biochemical things, so spleen belongs to "soil"; Lung qi governs purgation, and gold has the characteristics of clearing away diarrhea and converging, so lung belongs to "gold"; Kidney has the function of controlling water and storing essence, and water has the characteristic of moistening the lower part, so kidney belongs to "water".

② Explain the internal relationship of physiological functions of human viscera. For example, the essence of kidney (water) nourishes the liver, the liver (wood) stores blood and nourishes the heart, the heat of heart (fire) warms the spleen, and the spleen (soil) turns into the essence of water valley to fill the lung, and the lung (gold) helps the kidney. This is the relationship between the five internal organs. The decrease of lung (gold) qi can inhibit the hyperactivity of liver yang; The smoothness of liver (wood) can relieve the depression of spleen and soil; The transportation of spleen (soil) can prevent the flooding of kidney water; Moistening kidney (water) can prevent excessive heart fire; Yang-heart heat (fire) can excessively restrict lung-qi-Jin-Qing-Su, which is the relationship between the five internal organs.

③ Explain the relationship between human body and external environment, such as the four seasons and five flavors of food. In a word, the application of the theory of five elements in physiology lies in explaining the unity of the interrelationship between human viscera and tissues, as well as between human body and external environment.

2. Explain the pathological influence between zang-fu organs.

For example, liver disease can disperse the spleen, and it is a tree to borrow soil; Spleen disease can also affect the liver, which is an insult to wood; Liver and spleen are the same diseases, which affect each other, that is, wood stagnation and soil deficiency or soil stagnation and wood stagnation; Liver disease can also affect the heart, which is a maternal disease and a child disease; Affecting the lungs is a disgrace to gold; Diseases that affect the kidneys, for children and mothers. This is true of liver disease, as is the pathological changes of other organs. The relationship between the five elements can be used to explain their pathological interaction.

3. Used for the diagnosis and treatment of diseases.

Application of (1) in disease diagnosis

Diagnosis of visceral diseases from color, taste and pulse. If you see a blue face, like to eat sour taste, and see a string pulse, you can diagnose liver disease; Red face, bitter taste and red pulse can be diagnosed as excessive heart fire. Patients with spleen deficiency have a blue face and take soil as wood; Heart disease patients, see the dark, take fire as water, and so on.

Diagnose the spread of five zang-organs diseases from its color, taste and pulse. For example, patients with spleen deficiency have a blue complexion and a string-like pulse, which disperses the spleen for liver disease (wood with soil); Patients with lung disease have a red face, red ears and red pulse, which means that heart disease has spread to the lungs. Any one of the five internal organs has pathological changes, which can spread to the other four internal organs. According to the theory of five elements, there are four transmission and change relationships: reproduction, mutual offense, maternal disease, child disease and maternal disease.

Judging the prognosis of diseases from the relationship between color and pulse. If the liver disease looks blue, see the string pulse, which is consistent with the color pulse. If you don't see the string pulse but see the floating pulse, it is a mutually winning pulse, and the pulse of Kese (Jin Kemu) is reverse, and the main prognosis is poor; If the pulse condition is deep, it belongs to the interrelated pulse condition, that is, the color-producing (aquatic wood) pulse condition, which is smooth and has a good prognosis.

(2) Application in disease treatment

(1) Control the spread of diseases of the five internal organs. If liver disease can disperse spleen (wood with soil), replenish spleen in advance to prevent its spread. "When you see the disease of the liver, you know that the liver has to pass on the spleen, so you must first consolidate your temper."

② Determine the principle of treatment. It is summarized as the method of "tonifying the mother and purging the child", that is, "deficiency is tonifying the mother, but it is actually purging the child" Tonifying the mother is aimed at the deficiency syndrome of mother-child relationship, such as tonifying the kidney because of liver deficiency, because the kidney is the mother of the liver, so tonifying the kidney water can produce liver wood. Diarrhea is treated according to the evidence of mother-child relationship, such as liver excess purging heart, because heart is the son of liver, purging heart fire helps purging liver wood.

For example, it can be summarized as the method of "suppressing strength and reducing skin", and the treatment principle is determined according to the relationship between them, that is, suppressing strength and reinforcing weakness. If the liver wood is too strong and the spleen soil is too strong, it must be diarrhea and the spleen soil is weak, so it must be supplemented.

(3) Formulate treatment methods. In terms of drug treatment, such as nourishing water and burying trees, it is a method of nourishing kidney yin and preserving liver yin, which is suitable for diseases with kidney yin deficiency and liver yin deficiency. Another example is the method of nourishing the soil and producing gold, that is, the method of invigorating the spleen and benefiting the lung, which is suitable for the diseases of spleen deficiency and lung deficiency. Another example is the method of supporting soil and restraining wood, which is a method of treating liver depression and spleen deficiency with drugs that soothe the liver and strengthen the spleen.

In addition, in acupuncture and psychotherapy, the restraint of the five elements can be used to select points and adjust emotions. If sadness can overcome anger, it is because sadness belongs to the lungs and anger belongs to the liver.

In the process of practical application, the theory of Yin-Yang and Five Elements is often interrelated and inseparable. The combination of yin-yang and five elements theory can not only explain the general relationship between two contradictory sides of things, but also explain the more specific and complex relationship between things, which is conducive to explaining complex life phenomena and pathological processes.