IV. The Vessels
The vessels refer to the blood vessels which are distributed all over the body. These vessels are closely related to the heart and lung. The heart is linked to the blood vessels to form a relatively independent system;while the lung dominates the qi and meets all vessels to aid the heart's function of circulating blood. Therefore, the physiology.and pathology of both the heart and lung are closely related with the function of vessels.
The main physiological functions of the vessels are as follows. First, they are the passages through which the qi and blood circulate. The circulation and perfusion of the qi and blood take place within the blood vessels,which bind to the qi and blood. Thus,the blood circulates in certain directions and paths. Chapter 17 in Plain Questions states £º"The vessels provide residence for the blood. " Second, the vessels carry the essential substances of drink and food to the entire body. Only by relying on the blood vessels can sustenance be conveyed throughout the body to nourish the viscera ,allowing the normal physiological activities of all the internal organs and tissues to be maintained.
The vessels function in transporting nutrition and circulating the qi and blood is related with the functional activities of the heart, liver, spleen, and lung, etc. Disorders of the vessels are actual reflections of the pathological changes of the viscera mentioned above. If the functions of these viscera are abnormal, the vessels' function will be affected,and hemorrhage ,blood stasis ,sclerosis ,or deformity of the blood vessels may result.
In addition ,the cold-evil from the natural environment may attack the blood vessels causing spasms of the vessels. This is characterized by a lack of warmth in the extremities,pain in the body and limbs ,even gangrene ,etc.
