[PDF ]Wuxing (the five elements)-Part Three
Explaining the physiological functions of the five zang-organs and the relationships among them
The theory of the five elements explains the physiological characteristics and functions of the five zang-organs according to the attributes of the five elements, pairing each of the five zang-organs with the corresponding one of the five elements. For example, wood is characterized by free development while the liver prefers freedom to stagnation, so the liver pertains to wood; fire is hot and tends to flame up while heart-yang warms the whole body, so the heart pertains to fire; earth receives and generates while the spleen transforms food nutrients and is the source of qi and blood, so the spleen pertains to earth; metal depurates and astringes while lung-qi maintains inside and normally descends, so the lung pertains to metal; water moistens and closes while the kidney stores essence and manages water metabolism, so the kidney pertains to water.
Some of the intrinsic relationships among the functional activities of the five zang-organs also reflect the relationships of inter-promotion and inter-restraint. So they can be explained with the theory of inter-promotion and inter-restraint among the five elements. In terms of inter-promotion, the state of wood promoting fire corresponds to the state of the liver promoting the heart because liver-blood can nourish heart-spirit; the state of fire promoting earth corresponds to the state of the heart promoting the spleen because heart-spirit can regulate the transporting and transforming functions of the spleen; the state of earth promoting metal corresponds to the state of the spleen promoting the lung because the spleen can transports and transforms food nutrients to nourish the lung; the state of metal promoting water corresponds to the state of the lung promoting the kidney because the lung depurates and descends qi to help the kidney receive qi; the state of water promoting wood corresponds to the state of the kidney promoting the liver because kidney-yin can nourish liver-yin. In terms of inter-restraint, the state of wood restraining earth corresponds to the state of the liver restraining the spleen because liver-qi relieves stagnation of spleen-earth to bring the transporting and transforming functions of the spleen into full play; the state of wood restraining water corresponds to the state of the spleen restraining the kidney because the spleen governs metabolism of water to prevent edema due to abnormal flow of kidney-water; the state of water restraining fire corresponds to the state of the kidney restraining the heart because sufficient kidney-yin can assist the heart to control hyperactivity of heart-fire; the state of fire restraining metal corresponds to the state of the heart restraining the lung because the warmth of heart-yang can prevent lung-qi from excessively depurating and descending; the state of metal restraining wood corresponds to the state of the lung restraining the liver because lung-qi depurates and descends to prevent liver-qi from excessively ascending.
Explaining interactions among the five zang-organs
The human body is an organic whole. The five zang-organs coordinate with each other physiologically and affect each other pathologically. Under pathological condition, disorder of one organ may be transmitted to another. According to the theory of the five elements, there are two aspects of pathological transmission among the five zang-organs., one includes over restraint and reverse restraint, the other includes disorder of the mother-organ involving the child-organ and disorder of the child-organ involving the mother-organ.
Over restraint and reverse restraint are pathological transmissions due to abnormal change of inter-restraint relationship. Over restraint refers to transmission of disease due to excessive restraint, the order of which is the same as that of inter-restraint. For example, if liver-qi attacks the spleen, spleen-qi will be weakened, leading to dysfunction of the spleen. Reverse restraint refers to transmission of disease due to opposite restraint, the order of which is just contrary to inter-restraint. For example, the lung normally restrains the liver. But if liver-fire becomes hyperactive and invades the lung, it may lead to failure of the lung to depurate.
Mutual involvement or affection of the mother-organ and the child-organ reflects pathological transmission due to abnormal change of inter-promotion relationship. Disorder of the mother-organ involving or affecting the child-organ means that the disease is transmitted from the mother-organ into the child-organ, the order of which is the same as that of inter-promotion. For example, hyperactivity of liver-fire may affect the heart and bring on hyperactivity of heart-fire, leading to superabundance of both heart-fire and liver-fire. Such a transmission is called disorder of the mother-organ involving the child-organ. Disorder of the child-organ involving or affecting the mother-organ indicates that the disease is transmitted form the child-organ into the mother-organ, the order of which is just opposite to that of inter-promotion. For example, prolonged deficiency of liver-yin affects the kidney and causes deficiency of kidney-yin. Such a transmission is called disorder of the child-organ involving the mother-organ, also known as "the child-organ consuming qi of the mother-organ".
Guiding clinical diagnosis
Since the five zang-organs pair with the five elements, the five colors, the five flavors and the five pulses respectively, and because the disorders of the internal organs can manifest on the surface of the body, clinically the theory of the five elements can be used to analyze the changes of complexion, taste and pulse in order to decide which viscus and meridian are involved.
Diagnosis according to complexion, taste and pulse
The five colors, the five flavors and the five pulses co