气血津液

Qi (氣) is at once the most central and the hardest concept in Chinese medicine to render in English. It is both the extremely fine material substance that constitutes the body and the functional activity of every organ and tissue. Qi is formless yet effective — invisible, but recognized by what it does. To translate it as "energy" captures something but misses its substantive aspect; to translate it as "matter" misses its dynamic, functional aspect.

The qi of the body is differentiated by source and distribution. Original qi (元气, yuán qì) is stored in the Kidneys, derived from one's prenatal endowment, and is the most fundamental. Gathering qi (宗气, zōng qì) accumulates in the chest, governing respiration and the circulation of blood. Nutritive qi (营气, yíng qì) flows in the vessels and gives rise to blood. Defensive qi (卫气, wèi qì) flows outside the vessels, warming the muscles, opening and closing the pores, and protecting against external pathogens.

Qi has five functional aspects: propelling (it moves blood and fluids), warming (it maintains body temperature), defending (it guards the surface against external pathogens), containing (it holds blood within the vessels and prevents loss of fluids and essence), and transforming (it drives the conversion of food into qi, qi into blood, and so on). A deficit of any one of these functions produces a corresponding pattern of disease.

Blood is generated from the refined essence of food and water, flows within the vessels, circulates throughout the body, nourishes the internal organs, moistens the sinews, bones, skin, and hair, and serves as the material substrate for mental activity. The classical phrase "blood is the spirit-qi" expresses a tight link between blood and consciousness in Chinese medicine: the Heart governs the vessels and houses the spirit, so when blood is full the spirit is settled and when blood is depleted the spirit "loses its dwelling" — producing insomnia, palpitations, and anxiety.

The relationship between qi and blood is summarized in two pairs of phrases: "qi is the commander of blood; blood is the mother of qi." Qi generates blood, moves blood, and contains blood within the vessels; blood, in turn, carries qi and provides its substantive base. This is why bleeding patterns are so often treated by tonifying qi (to restore the containing function), and why fatigue and breathlessness are often investigated for an underlying blood deficiency.

Jin-ye (津液, jīn yè) is the collective term for all normal physiological fluids in the body, distinguished by relative clarity and weight. Jin are the lighter, thinner fluids that disperse to the skin, muscles, and orifices, providing moisture (sweat, saliva, tears, the moisture of the mucous membranes). Ye are the heavier, more viscous fluids that pool in the joints, the brain, and the deeper organs, providing rich nourishment (synovial fluid, cerebrospinal fluid, the lubricating fluids of the viscera). The two are not sharply separated — they interconvert — but the distinction is clinically useful when judging which kinds of fluid have been lost or are stagnating.

The production, distribution, and elimination of fluids depend on the coordinated action of three organs: the Spleen transforms food and drink into refined essence, the Lung moves and regulates the water passages, and the Kidney drives the steaming transformation that lifts pure fluids upward and excretes the turbid as urine. When this triple coordination fails, fluids accumulate abnormally and become phlegm (痰, tán), thin mucus (饮, yǐn), or edema (水, shuǐ); when fluids are exhausted, dryness patterns appear, with cracked lips, dry stools, and a parched tongue.

In the clinic, qi, blood, and jin-ye are best understood not as three separate things but as three expressions of the same vital matrix — generated together, circulated together, and lost together when illness is severe.