1. The Six External Pathogens
1-1. Pathogenic Wind
1-2. Pathogenic Cold
1-3. Pathogenic Summer Heat
1-4. Pathogenic Damp
1-5. Pathogenic Dryness
1-6. Pathogenic Fire (Heat)
2. Epidemic Pathogens
3. Internal impairment by the Seven Emotions
3-1. Concept of the Seven Emotions
3-2. Characteristics of the Seven Emotions as pathogenic factors
3-3. Impairing the internal organs
3-4. Disturbing flow of Qi
3-5. Worsening or deterioration of a disease
4. Improper Diet and. Imbalance Between Work and Rest
4-1. lmproper diet leading to disease
4-2. Imbalance between work and rest
5. Traumatic injuries
In the view of TCM , health is a state in which the relations of the components of the human body and the unity between man and nature are kept in harmony. When this harmony is destroyed by certain factors and the body cannot maintain its normal state , disease occurs. So , any factors that destroy the relative balance of the human body are known as causes of disease in TCM.
Etiology in TCM is characterized by three points : First, recognizing etiologic factors under the guidance of the Concept of Holism. Unlike Western medicine, TCM does not emphasize the identification of the specific etiologic factors such as viruses and bacteria of diseases. Instead, it stresses the significance of the environmental or internal conditions of the human body in the occurrence of disease. For example, man depends on the supply of both Heaven Yang and Earth Yin, which affect the human body through different climatic conditions and food and drink. Therefore , abnormal changes of the weather or climatic conditions are regarded as one of the major groups of pathogenic factors that invade the body from the outside; and improper diet , such as excessive or inadequate intake of food, or preference for food of certain tastes , are pathogenic factors that directly disturb the functional activities of the Zang and Fu Organs.
In addition, emotional stress, if in excess, may also become a pathogenic factor as it will lead to dysfunction of the Zang and Fu Organs.
Second, stressing the relativity of pathogenic factors. Whether or not abnormal changes of any factors, such as climatic conditions or emotional changes, can transform into pathogenic factors depends not only on the changes themselves , but also the reaction of the human body to these changes. For example, a sudden and violent climatic change may become one of the Six External Pathogens , but if its effect is limited for some reason, or the resistance of the body is strong enough to defend the body, it will not cause diseases. In such conditions ,it cannot be regarded as one of the Six External Pathogens. Abnormal changes of weather provide the possibility for climatic conditions to become pathogens, but it is the mutual action of the climatic conditions and Vital Qi that determines whether the abnormal weather transforms into a pathogen or not.
Third, identifying pathogenic factors by analyzing the manifestations of a disease. TCM believes that any syndrome is a morbid reflection of the human body under the action and influence of pathogenic factors. There is a correspondence between the pathogens and the manifestations of disease. Therefore, when analyzing causes of a disease, apart from possible objective considera- tions , TCM deduces the nature of the pathogens mainly on the basis of the manifestations. For example, when a patient has fever and chills, lack of sweat, stuffy and running nose and a floating tense pulse, he can be diagnosed as having an Exterior Syndrome due to Wind Cold. Whether or not it is very cold during the occurrence of the disease is not very important in the determination of the pathogens.
1. The Six External Pathogens
This is a general term for Wind, Cold, Summer Heat, Damp, Dryness and Fire. The six kinds of climatic changes in excess, which usually invade from outsidethe body to cause diseases. They are transformed from the six kinds of climatic changes, which, in normal conditions, are the basic conditions for the survival of the human being. In the long period of evolution, man has gradually developed the ability to adapt himself to the changes of weather. However, when these changes are excessive and go beyond the adaptability of the human body, they may disturb the functional activities of the human body, turning into pathogenic factors. As they invade the human body from the outside, diseases caused by them are referred to as External diseases. Generally speaking , the Six External Pathogens have the following common characteristics:
First , invasion of the Six External Pathogens into the human body is closely related to the climatic conditions in different seasons and the environment one lives in. Diseases related to Wind occur more frequently in spring because Wind is prevalent in this season. Summer Heat attacks the body only in the summer because it exists only in this season. Living for a long time in a damp place, one is likely to suffer from arthritis. And working in a hot environment, one is liable to be invaded by Heat and Fire.
Second, each of these pathogens can cause disease alone or in combination with other pathogens. For example, Wind may attack the body alone, causing an Exterior Syndrome due to Wind, or in combination with Cold or Heat, causing Exterior Syn- dromes due to Wind Cold or Wind Heat, or in combination with both Cold and Damp to cause arthralgia.
Third, because they originate in the external environment, the Six External Pathogens invade the body mainly through the skin, or the nose and mouth, the Organs and tissues exposed to the environment.
Fourth, the Six External Pathogens can act not only on one another in the occurrence of diseases, but can transform into each other in accordance with the constitution of an individual. As a result, the nature of the disease's pathogenesis and Syndrome changes accordingly. For example, Cold may transform into Heat due to the Yang Excess constitution of a patient when it invades from the Exterior to the Interior; while Damp, in the case of interlocking in the interior of the body and obstructing the distribution of Body Fluids, may be transformed into Dryness.
1-1. Pathogenic Wind
Wind prevails in spring, but it also exists all the year round. So diseases caused by Wind can be seen in all four seasons. Wind in excess is known as pathogenic Wind, which serves as the most important External pathogen and usually invades the human body by attacking the superficial muscles and skin first. Pathogenic Wind possesses the following features: First, wind is air in motion. Being a pathogen of Yang nature, Wind tends to cause loose striae of muscles, and disease caused by Wind usually occurs in the upper body. As Wind is mobile, going upwardand outward, it is a yang pathogen. When it attacks the body, it tends to attack the superficial muscles, the Yang Channels and the upper part of the body. So, Wind often causes such symptoms as sweating and hesdache.
Second, wind has the property of moving and changing. This means that Wind is mobile in nature and it may cause shaking of trees. So diseases caused by Wind are characterized by their migratory symptoms, sudden onset, and rapid progression. For example, rheumatic arthralgia caused mainly by pathogenic Wind is marked by migratory pain of the joints, and urticaria, which is due to invasion of pathogenic Witid, is marked by migratory itching of the skin and its intermittent occurrence. Third , wind is the predominant pathogen. As Wind exists all year round, it can cause diseases whenever the defensive ability of the body declines. Therefore, a great variety of diseases are related to the invasion of Wind. Furthermore, as Wind is in a state of constant motion and tends to cause loose striae of muscles, other pathogens usually attack the human body following the invasion of pathogenic Wind. So external diseases are usually ascribed to pathogenic Wind or Wind in combination with other pathogenic factors.
1-2. Pathogenic Cold
Cold is prevalent in winter. It usually attacks the body when the temperature is low and man fails to adapt himself to the change by dressing properly. Pathogenic Cold may attack the Exterior of the body or invade the interior of the body directly. Diseases in the former case are called affliction pf pathogenic Cold, and those in the latter case, direct attack of Cold on the interior.
Pathogenic Cold has the following features:
First, being a Yin pathogen, Cold tends to impair Yang Qi. Cold is the prevalent climate in winter, in which Yin Qi of nature is flourishing, so it is a Yin pathogen. Like attracts like. So Yin of the body will become hyperactive in the case of invasion of Cold and Yang Qi is overrestricted. For example, Cold attacking the Exterior often obstructs Defensive Qi (one kind of Yang Qi), leading to failure of the Exterior to be warmed and resultant chills. Direct attack of Cold on the Spleen and Stomach usually cause Cold pain in the abdomen, watery diarrhea, etc. , meaning that Spleen Yang is impaired and its transforming and transporting actions are disturbed.
Second, cold is liable to cause coagulation of Blood and retention of Body Fluids. Blood and body fluids depend on the propelling effect of Yang Qi and a moderate temperature for their free circulation. If Cold invades the body, Yang Qi will be impaired and body temperature will be lowered. So the flow of Blood and Body Fluids will become sluggish, or even coagulated, which is clinically marked by pain. For example, rheumatic arthralgia mainly due to pathogenic Cold is marked by Cold pain of the joints, which is usually severe and fixed.
Third, contracting nature of Cold. This means that pathogenic Cold often leads to ingoing of Qi , contraction of the muscular striae and convulsion of tendons and vessels. If attacked by pathogenic Cold, the muscular striae and the sweat pores will be closed, so Defensive Qi will be obstructed, and fever or chills and absence of sweating will occur as a result. Invasion of patbogenic Cold into the vessels will cause coagulation of Qi and Blood and contraction of the vessels, leading to headache, pantalgia, tense pulse, etc. Inability of the limbs to flex and extend freely or Cold and numbness of the limbs will follow if the Cold attacks the Channels and joints and results in contraction of the tendons and Channels.