Despite their differences in nature, form and function, qi, blood and body fluid have something in common with each other. They are the basic materials that constitute the human body and maintain life activities; they all derive from cereal essence; they, physiologically, depend on each other for existence and restrain and utilize each other; they, pathologically, act upon each other and have causality between them.

Qi and blood are closely related. Qi is the “commander” of blood, and blood is the “mother” of qi. As the commander of blood, for one thing, qi is the motive power for blood formation, or rather, it produces blood. Blood is formed from mutritive qi and body fluid, both of which come from food and water. All these cannot be separated from the functions of qi. Blood circulation depends on the propelling function of heart-qi. For another, qi controls blood and keep it flowiing in the blood vessels without extravasation. This function of qi is performed by spleen-qi. When qi is deficient, it fails to control blood, thus leading to hemorrhage. Blood is referred to as the mother of qi because, on the one hand, blood is a carrier of qi; and on the other, blood provides adequate nutrients for qi. Therefore, it is impossible for qi to exist without its”mother”, blood.

The relationship between qi and body fluid is rather similar to that between qi and blood. This is shown in the following four aspects. First, qi produces body fluid. The formation, distribution and excretion of body fluid depend upon all the movements of qi and its warming, promoting and controlling functions. The existence of qi in the body not only depends upon blood, but on body fluid which is formed from food essence by the functions of the stomach and spleen. So, whether body fluid is adequate or inadequate depends upon the conditions of spleen-qi and stomach-qi. Second, qi promotes the transportation of body fluid. The movements of qi are the motivity for the transportation, and distribution of body fluid, and the excretion of sweat and urine. Therefore, In case of deficiency of qi or dysfunction of qi, disturbance of body fluid in transportation, distribution and excretion will occur. Thereby leading to the stagnation of body fluid. Third, qi controls body fluid. Qi may control the excretion of body fluid and maintain the balance of the metabolism of body fluid, In case qi fails to control the excretion of body fluid some of body fluid will run off. Fourth, body fluid is a carrier of qi.(Qi resides in body fluid, Body fluid serves as a carrier of qi) That is, body fluid carries qi. Qi cannot exist without body fluid. This is the reason why the loss of body fluid often damages qi. If qi fails to attach to body fluid, qi-deficiency and even qi prostration will ensue. So the medical book Prescriptions of the Golden Cabinet says:”No one has perfect qi after hidrosis, vomiting etc.” Examples in point are:hidrosis, polyuria, enormous vomiting and diarrhea cause great loss of body fluid, which, in turn, gives rise to qi colapse.

Blood and body fluid are liquids and, what’s more, they both perform the nourishing and moistening functions. Body fluid will become and important component of blood when infiltrating into the blood vessels. As blood and body fluid originate from the essence of food and water, they are known as “body fluid and blood are derived from a common source.” Recurrent or severe bleeding may do damage to body fluid, resulting in thirst, scanty urine and dry skin. And severe consumption or loss of body fluid will affect the source of blood, leading to the exhaustion of both blood and body fluid. For this reason, it is not advisable to use diaphoretics for haemorrhagic patients, and the methods of breaking blood or pricking blood should be avoided in treating patients with the inadequate of body fluid and hidrosis. Miraculous Pivot states:” The patients lost bolld should avoid perspiring; while the patients lost perspiration should avoid Losing blood.” And “the first contraindication refers to emaciated patients; the second to patients lost blood; the third to patients after severe perspirationl;the fourth to patients after severe diarrheal and the fifth to patients of postpartum hemorrhage. Purgation is contraindicated in all these cases.”

To sum up, the close and complicated relationships between the three are often shown in physiology and pathology, and are of great importance in TDS.