What is meant by pathogenesis? By pathogenesis is meant the mechanism of the occurrence, development and outcome of diseases. The occurrence, development and outcome of diseases are closely related both to the body’s vital qi and to the nature of the pathogenic factors. When the pathogens attack the human body, the body’s vital qi is bound to rise against the pathogens, forming the conflict between vital qi and pathogens. Their conflict is bound to destroy the relative balance of yin and yang to cause the dysfunction of the zang-fu organs and meridians, or the disturbance of qi and blood. Thus bringing about a variety of local or general pathological changes. Notwithstanding various diseases and complicated clinical manifestations, their changes of pathogenesis, in general, are inseparable from the excess or deficiency between the vital-qi and the pathogens, the imbalance of yin and yang, or the abnormably of qi and blood and the dysfunction of the zang-fu organs and meridians.

The conflict between the vital-qi and pathogens is not only related to the occurrence of a disease, but also directly affects its development and final outcome. Meanwhile, it has a direct influence on deficient or excessive changes of the syndromes in a certain sense, the processes of many diseases are seen as those of the changes of excess and deficiency in the contest between the vital-qi and pathogens. Therefore, vicissitudes of vital qi and pathogens are considered to be one of the pathogenesises.

Basic Questions says “the exuberance of pathogens results in excess syndrome, while the depletion of essence-qi may bring on deficiency syndrome.” Excess refers to excess of pathogens, or a pathogenic reaction with excessive pathogens as the principal aspect of the contradiction.

That is to say, the pathogens are excessive, the vital qi is also strong. Clinically, a sort of pathological reactions of excess ensue with the fierce and obvious struggle between vital qi and pathogens, which is known as excess syndrome. It is mostly found in the early or middle stage of diseases caused either by the six exogenous pathogens or by the phlegm retention, undigested food, blood stasis, etc. , characterized by high fever, mania, high voice and coarse breathing, abdominal pain with tenderness, obstructive urination and defecation, and full and forceful pulse.

By deficiency syndrome is meant a syndrome caused by inadequate of vital qi, or a pathological reaction with the deficiency of vital qi as the dominant factor of the contradiction. That is, the vital qi become too deficient to resist pathogens because of the dysfunctions of qi, blood, body fluid, zang-fu organ and meridians. Consequently, the conflict of vital qi and pathogens may not produce intense pathological reaction and a series of insufficient manifestations arise, so called deficiency syndrome. This types of syndrome is mostly seen in patients with weak constitutions or in the later stage of a disease and in different kinds of chronic cases, marked by lassitude, pallid complexion, palpitation, short breath, spontaneous perspiration, night sweat feverish sensation in the chest, palms and soles or aversion to cold, cold extremities, feeble pulse, etc.

The rise and fall of vital qi and pathogens can bring about mixed syndromes of excess and deficiency in protracted and complicated diseases. Such syndromes have mainly two kinds of pathological changes: deficiency syndromes mixed with excess ones and excess syndromes mixed with deficiency ones. However, under some particular circumstances, there will be two types of pathological changes: true excess syndrom with pseudo-deficiency symptoms and true deficiency with pseudo-excess symptoms. The former is said to be “symptoms of pseudo-excess in extreme deficiency”, while the latter is said to be “symptoms of pseudo-deficiency in extreme excess”. From the above, to identify a deficiency or excess syndrome of pathogenesis we must see through the appearance to get at the essence and

so only can we not be misted by false phenomena and accurately grasp the changes of excess or deficiency syndrome .

In the course of a disease, the conflict between vital qi and pathogens not only gives rise to their deficiency or excess, but also causes the outcome of a disease. When vital qi prevails over pathogens, the disease tends to improvement or even complete recovery. Otherwise, when pathogens prevail over vital qi, the disease tends to deterioration or even life comes to end.

In the course of occurrence, development and final outcome of a disease, disharmony of yin and yang will occur under the action of pathogens, resulting in such pathological manifestations as relative excess or deficiency of either yin or yang, mutual impairment, repellence and depletion of yin and yang.

The Disturbance of qi and blood refers to a morbid state caused by deficiency and dysfunction of qi and blood, and the breakdown of their interdependent relationship. Qi and blood in the body are the material basis for the physiological activities of the zang-fu and meridians. Therefore, their disturbance will inevitably affect the body’s function to cause diseases. Basic Questions states: “The disharmony between qi and blood will result in various diseases”. However, qi and blood are the products of the functions of the zang-fu organs. Pathological changes of the zang-fu organs may not only lead to qi-blood disturbance, but also affect qi and blood of the whole body. Thus, the pathogenesis of qi-blood disturbance, like that of the rise and decline of vital qi and pathogens and the imbalance of yin and yang, is not only the root cause of pathological changes of the zang-fu organs and meridians, but also the basis for the analysis and research of the pathogenesis of various diseases.

The failure of qi activity refers to such pathological changes as qi stagnation, adverse flow of qi, qi sinking, qi blockage and qi exhaustion due to disturbance in its ascending, descending, exiting and entering. Ascending, descending, exiting and entering are the basic form of qi movement, on which functional activities of the zang-fu organs and meridians as well as the relation ships between the zang-fu organs and meridians, qi and blood, and yin and yang depend to maintain their relative balance. Fort his reason, the disorder of qi activity may bring about various morbid conditions involving the zang-fu organs, qi and blood, yin and yang, exterior and interior, four limbs and nine orifices.

The disorder of blood includes deficient blood production, blood deficiency caused by massive hemorrhage, over consumption of blood caused by prolonged illness, or dysfunction of blood nourishment; it also includes the accelerated blood circulation caused by blood heat and blood stasis caused by sluggish blood circulation.

The metabolism of body fluid is essentially the processes of continuous production, distribution and excretion of body fluid. The disturbance of the metabolism means the disturbance of distribution and the imbalance between production and excretion, thus causing deficiency production of body fluid to form fluid retention in the body, So, normal metabolism of body fluid is the basic condition maintaining normal distribution, production and excretion. Normal production, distribution and excretion of body fluid are inseparable from ascending, descending, exiting and entering movement of qi and its transforming function. And also. they cannot be separated from the functions of the lung, spleen, liver, kidney and the triple energizer.

The five endogenous pathogens refer to the pathological changes caused by the dysfunction of qi, blood, body fluid and the zang-fu organs, namely endogenous wind, endogenous cold, endogenous dryness ， endogenous fire and endogenous dampness. They are not pathogenic factors; they are five comprehensive changes of pathogenesis.

Special phrases

1.The disharmony of qi and blood may cause various diseases.

2.Heat-transformation, fire-transformation, wind-transformation, dryness-transformation, dampness-transformation

3.Insufficiency of vital qi is the intrinsic factor of the occurrence of disease.

4.Pathogenic factors are the predominant factor of disease.