Yin and Yang

Yin and yang form a pair of principles used to generalize categories of syndromes. Being the key link in the application of the eight principles, yin and yang are used to summarize the other three pairs of principles. Exterior, heat and excess fall into the category of yang, while interior, cold and deficiency fall into the category of yin. Yin and yang are also used to explain some of the pathological changes of the zang - fu organs and tissues, e.g. syndromes of collapse of Yin, syndromes of collapse of yang, syndromes of yin deficiency, syndromes of yang deficiency.

Yin syndromes and yang syndromes. Yin syndromes refer to pathological conditions resulting from deficiency of yang qi in the body and retention of pathogenic cold. Yang syndromes refer to pathological conditions caused by hyperactivity of yang qi in the body and excess of pathogenic heat. Syndromes of deficiency type and cold syndromes come within yin syndromes ; syndromes of excess type and heat syndromes come within yang syndromes. Generally speaking, so far as clinical manifestations are concerned, those characterized by excitation, fidgeting, hyperactivity and bright complexion fall into the category of yang syndromes, while those characterized by inhibition, quiescence, hyperactivity and sallow complexion fall into the category of yin syndromes.

Collapse of yin and collapse of yang. Collapse of yin refers to pathological conditions resulting from massive consumption of yin fluid. Collapse of yang refers to pathological conditions caused by extreme exhaustion of yang qi in the body.

Both collapse of yin and collapse of yang are critical syndromes in the process of a disease. They may result from the further aggravation of yin deficiency and yang deficiency. They may also occur as a result of an abrupt aggravation in acute diseases, e.g. severe vomiting and diarrhea or great loss of blood may elicit collapse of yin, and profuse sweating may cause collapse of yang.

As yin and yang depend upon each other, in the case of collapse of yin, the yang qi has nothing to depend upon, and therefore it dissipates from the body. In collapse of yang, yin fluid is also consumed. However, the predominating factors in the two syndromes are different, and corresponding methods of treatment must be adopted.

In addition to the various critical symptoms and signs of the disease which occur initially, sweating may be seen in the both syndromes. The distinguishing points are described as follows :

Collapse of Yin - Sticky sweat, feverishness of the body, warm hands and feet, shortness of breath, irritability, restlessness, thirst with preference for cold drinks. Red and dry tongue. Thready, rapid and weak pulse.

Collapse of Yang - Profuse cold sweat like pearls, coolness of the body, cold hands and feet, feeble breathing, listlessness, absence of thirst or preference for hot drinks. Pale and moist tongue. Thready and fading pulse.