脏腑

The doctrine of the zang-fu organs is the central anatomical-functional framework of Chinese medicine. It divides the internal organs into two classes: zang (臟) and fu (腑). Zang means "to store" — the zang organs store the refined essential substances of the body and do not discharge them. Fu means "hollow administrative quarters" — the fu organs receive food and drink, transmit them through the body, and discharge waste; they are full only intermittently and do not store essence.

The five zang are the Heart (心), Liver (肝), Spleen (脾), Lung (肺), and Kidney (肾). They are yin organs, characterized by storage and stillness. The six fu are the Gallbladder (胆), Stomach (胃), Small Intestine (小肠), Large Intestine (大肠), Bladder (膀胱), and Triple Burner (三焦). They are yang organs, characterized by motion and discharge. Each zang is paired with one fu in an interior-exterior relationship: Lung with Large Intestine, Heart with Small Intestine, Spleen with Stomach, Liver with Gallbladder, Kidney with Bladder, and the Pericardium (often counted with the zang) with the Triple Burner.

A crucial caution for any reader trained in Western medicine: although the zang-fu organs share their names with Western anatomical organs, they are not the same things. The Chinese terms denote functional systems — clusters of physiological activities, tissue relationships, and emotional and mental functions associated with the named organ — and they map only loosely onto their anatomical namesakes. Reading "Spleen" as the cardiac muscle or "Spleen" as the abdominal lymphoid organ will mislead at almost every step.

Heart (心): governs the blood and vessels, and houses the shen (神, spirit). The Heart's functions are not limited to pumping blood — it also governs consciousness, mental activity, and emotional stability. Heart-qi deficiency produces shortness of breath and fatigue; Heart-blood deficiency produces insomnia and dream-disturbed sleep; Heart-fire blazing produces agitation and oral ulcers.

Liver (肝): governs the free flow of qi (疏泄, shū xiè), and stores the blood. The free-flowing function regulates the smooth movement of qi throughout the body and the smooth flow of emotions. Storage of blood means the Liver regulates the volume of blood available to the periphery according to need. Loss of free flow produces hypochondriac distention, irritability, and menstrual irregularity; deficiency of Liver-blood produces blurred vision and brittle nails.

Spleen (脾): governs transportation and transformation, and contains the blood. "Transportation and transformation" (运化, yùn huà) names the entire process of digestion, absorption, and distribution of refined essence from food and drink. "Containing the blood" means the Spleen-qi keeps blood within the vessels. A deficient Spleen produces poor appetite, loose stools, and fatigue; a Spleen that fails to contain blood produces chronic bleeding, including blood in the stool and abnormal uterine bleeding.

Lung (肺): governs qi and respiration; governs the dispersing and descending of qi; regulates the water passages. The Lung opens to the nose, controls the skin and body hair, and is the most superficial of the zang organs — making it the first line of defense against external pathogens. A deficient Lung produces shortness of breath and susceptibility to colds; failed dispersion and descent produce cough and wheezing.

Kidney (肾): stores the essence (精, jīng); governs water; receives the qi from the Lung. The Kidney stores both the prenatal essence inherited from one's parents and the postnatal essence refined from food, and so governs growth, development, reproduction, the bones, the marrow, the brain, hearing, and the lower back. A deficient Kidney produces lumbar weakness, premature aging, reduced fertility, tinnitus, and weakness of the bones.

The six fu share a common operating principle: "they are useful through being open, and well-ordered through descending" (以通为用, 以降为顺). Their health consists in continual movement — none should stagnate or accumulate. The Gallbladder stores and discharges bile and governs decision-making. The Stomach receives food and "rotten-ripens" (initial digestion of) food and drink. The Small Intestine receives the partially digested contents from the Stomach and separates the clear (essence to be absorbed) from the turbid (waste to be passed on). The Large Intestine transmits and discharges the waste. The Bladder stores and discharges urine.

The Triple Burner (三焦, sān jiāo) is the most distinctive of the fu and has no single anatomical correlate. It is best understood as the name for three functional regions of the body considered together — the upper burner (the chest, where the Heart and Lung distribute qi and fluids "like a mist"), the middle burner (the area of the Spleen and Stomach, where food and drink are "fermented like a brewing vat"), and the lower burner (the lower abdomen, the area of the Liver, Kidney, intestines, and Bladder, which discharge waste "like a drainage ditch"). Through the Triple Burner the qi and fluids of the entire body are circulated and coordinated.