Zangfu

The zangfu organs are functional entities stipulated by traditional Chinese medicine (TCM). These classifications are not based in physiology or science. They constitute the technological centrepiece of TCM's general concept of how the human body works. The term zang refers to the organs considered to be "solid" yin in nature – Heart, Liver, Spleen, Lung, Kidney – while fu refers to the "hollow" yang organs – Small Intestine, Large Intestine, Gall Bladder, Urinary Bladder, Stomach and San Jiao.

Each zang is paired with a fu, and each pair is assigned to one of the wuxing. The zangfu are also connected to the twelve standard meridians – each yang meridian is attached to a fu organ and each yin meridian is attached to a zang. They are five systems of Heart, Liver, Spleen, Lung, Kidney.

To highlight the fact that the zangfu are not equivalent to the anatomical organs, their names are often capitalized.

Anatomical organs
To understand the zangfu it is important to realize that their concept did not primarily develop out of anatomical considerations. The need to describe and systematize the bodily functions was more significant to ancient Chinese physicians than opening up a dead body and seeing what morphological structures there actually were. Thus, the zangfu are functional entities first and foremost, and only loosely tied to (rudimentary) anatomical assumptions.

Yin/yang and the Five Elements
Each zangfu organ has a yin and a yang aspect, but overall, the zang organs are considered to be yin, and the fu organs yang.

Since the concept of the zangfu was developed on the basis of wuxing philosophy, they are incorporated into a system of allocation to one of five elemental qualities (i.e., the Five Elements or Five Phases). The zangfu share their respective element's allocations (e.g., diagnostics of colour, sound, odour and emotion etc.) and interact with each other cyclically in the same way the Five Elements do: each zang organ has one corresponding zang organ that it enfeebles, and one that it reinforces.

The correspondence between zangfu and Five Elements are stipulated as:


 * Fire (火) = Heart (心) and Small Intestine (小肠) (and, secondarily, Sanjiao [三焦, ‘’Triple Burner‘’] and Pericardium [心包])
 * Earth (土) = Spleen (脾) and Stomach (胃)
 * Metal (金) = Lung (肺) and Large Intestine (大肠)
 * Water (水) = Kidney (肾) and Bladder (膀胱)
 * Wood (木) = Liver (肝) and Gallbladder (胆)

Details
The zang organs' essential functions consist in manufacturing and storing qi and blood (and, in the case of the Kidney, essence). The hollow fu organs' main purpose is to transmit and digest (传化, ) substances (like waste, food, etc.).

Zang
Each zang has a corresponding "orifice" it "opens" into. This means the functional entity of a given zang includes the corresponding orifice's functions (e.g. blurry vision is primarily seen as a dysfunction of the Liver zang because the Liver channel "opens" into the eyes).

In listing the functions of the zang organs, TCM regularly uses the term "governing" – indicating that the main responsibility of regulating something (e.g. blood, qi, water metabolism etc.) lies with a certain zang.

Although the zang are functional entities in the first place, TCM gives vague locations for them – namely, the general area where the anatomical organ of the same name would be found. One could argue that this (or any) positioning of the zang is irrelevant for the TCM system; there is some relevance, however, in whether a certain zang would be attributed to the upper, middle or lower jiao.

Heart
The Heart:
 * "Stores" (藏, ) the shen (usually translated as "mind"), paired with small intestines
 * Governs xuě (blood) and vessels/meridians
 * Opens into the tongue
 * Reflects in facial complexion

Pericardium
Since there are only five zang organs but six yin channels, the remaining meridian is assigned to the Pericardium. Its concept is closely related to the Heart, and its stipulated main function is to protect the Heart from attacks by Exterior Pathogenic Factors. Like the Heart, the Pericardium governs blood and stores the mind. The Pericardium's corresponding yang channel is assigned to the San Jiao ("Triple Burner").

Spleen
The Spleen:
 * "Stores" the yi
 * Governs "transportation and transformation", i.e. the extraction of jing wei (, usually translated with food essence, sometimes also called jing qi [, essence qi]) – and water – from food and drink, and the successive distribution of it to the other zang organs.
 * Is the source of "production and mutual transformation" of qi and xue (blood)
 * "Contains" the blood inside the vessels
 * Opens into the lips (and mouth)
 * Governs muscles and limbs

Liver
The Liver:
 * "Stores" blood, and the hun (魂, Ethereal Soul) and is paired with the gall bladder.
 * Governs "unclogging and deflation" primarily of qì. The free flow and harmony of qì in turn will ensure the free flow of emotions, blood, and water.
 * Opens into the eyes
 * Governs the tendons
 * Reflects in the nails

Lung
Yin Metal. Home of the po (魄, Corporeal Soul), paired with the yang organ the Large Intestine.

The function of the Lung is to disperse and descend qi throughout the body. It receives qi through the breath, and exhales the waste and helps the peristaltic action of the gastrointestinal tract.The Lung governs the skin and hair and also governs the exterior (one part of immunity) and the closing of the skin pores. A properly functioning Lung organ will ensure the skin and hair are of good quality and that the immune system is strong and able to fight disease. The normal direction of the Lung is defending, when Lung qi "rebels" it goes upwards, causing coughing and wheezing. When the Lung is weak, there can be skin conditions such as eczema, thin or brittle hair, and a propensity to catching colds and flu. The Lung is weakened by dryness and the emotion of grief or sadness.

Kidney
Water. Home of the zhi (志, Will), paired with the Bladder.

The Kidneys store jing Essence, govern birth, growth, reproduction and development. They also produce the Marrow which fills the spinal cord, brain and control the bones. The Kidneys are often referred to as the "Root of Life" or the "Root of the Pre-Heaven Qi".

Criticism
The concept of the zangfu is not scientific – the underlying assumptions and theory have not been (and are not expected to be) verified or falsified by experiment. Probably because of this, the concept (and TCM as a whole) has been criticized as pseudoscientific.