Chinese Medicine : Basic Zang Fu Theory

The Zang-Fu Theory

The zang-fu theory explains the physiological function, pathological changes, and mutual relationships of every zang and fu organ. In traditional Chinese medicine the zang and fu organs are not simply anatomical substances, but more importantly represent the generalization of the physiology and pathology of certain systems of the human body.

Zang and fu consist of the five zang and six fu organs. The five zang organs are the heart (including the pericardium), lung, spleen, liver, and kidney. The six fu organs are the gall bladder, stomach, large intestine, small intestine, urinary bladder and the sanjiao (three areas of the body cavity). Zang and fu are classified by the different features of their functions. The five zang organs mainly manufacture and store essence: qi, blood, and body fluid. The six fu organs mainly receive and digest food, absorb nutrient substances, transmit and excrete wastes. As the Suwen says: The five zang organs store up essential qi and regulate its outflow. The six fu organs transform and transport substances without storing them and for this reason they may be over-filled but cannot be filled to capacity.3

There is another category of organs called the extraordinary fu organs which include the brain, marrow, bone, vessels, gall bladder, and uterus. They are named fu but their functions are similar to that of the five zang organs. Since their physiological functions and pathological changes are closely connected with the zang-fu organs they will be discussed below under the specific zang or fu organ.

The Five Zang Organs

1.1. Heart
The main physiological functions and indicators of the heart are: 1)domination of blood and vessels, and facial complexion; 2)control of the mind; and 3)opening into the tongue. The heart has an "exterior" (biao) and "interior" (li) relationship with the small intestine.

Dominating Blood and Vessels, and Facial Complexion
The heart dominates the blood and vessels indicating its function of promoting blood circulation. In the Suwen, it says, "...The heart is in charge of the blood vessels...."4 The vessels are the pathways of blood circulation while the heart is the motive power of blood circulation. Only if there is ample heart qi can the blood circulate incessantly in the vessels to nourish the whole body. The heart, blood, and vessels are interrelated. Because of the rich distribution of blood vessels in the facial region, the color and luster of the complexion usually reflects the sufficiency or insufficiency of the blood supply and heart qi. If the heart blood supply is sufficient, then the pulse beats normally and forcefully and the facial complexion is rosy with luster. If the heart qi is insufficient, the vessels will be empty, the pulse feeble and weak or irregular and the facial complexion pale. Insufficient heart qi may lead to blood stagnation manifested by a blue complexion. So in the Suwen is says, "The heart is the root of live, ...its luster is manifested in the face, it fills up the blood vessels...."5

Controlling the Mind
Mind here indicates spirit, consciousness, and thinking. Traditional Chinese medicine considers that mind refers to the five zang organs, especially the heart. So in the Lingshu it says, "The organ that is responsible for the performance of activities is the heart."6 This means the process of thinking is accomplished by the heart. Blood is the main foundation for mental activities, thus the function of heart controlling the mind is closely related to the function of heart dominating the blood and the vessels. If there is plenty of heart blood, the mind is clear, thinking is nimble, and one if full of vim and vigor. If heart blood is insufficient, it will lead to the pathological changes of heart-mind manifested by palpitation, insomnia, dream disturbed sleep, poor memory, restlessness, etc. If heat in the blood disturbs the heart-mind, there will be delirium, coma, etc.

Opening into the Tongue
One of the branches of the heart channel directly connects with the tongue. So physiologically the tongue has a close relationship with the heart. The qi and the heart blood all flow up to the tongue in order to assist its normal physiological functions. If there is a pathological change in the heart, it will be reflected in the changes of the tongue. For example, an insufficient supply of heart blood may be manifested by pale tongue proper; heart fire flaring up is reflected by red tongue proper, or even by ulcers of the tongue; blood stagnation in the vessels in presented by a purple tongue or purpura; pathogenic heat invading the pericardium or pathogenic phlegm obstructing the heart orifice, will produce coma, delirium, and stiffness of the tongue. Thus it is said, "The heart opens to the tongue," or "The tongue is the sprout of the heart."

1.2. Pericardium
The pericardium is called xinbaoluo in Chinese. Structurally it is a membrane surrounding the heart, and physiologically it protects the heart. When exogenous pathogenic factors attack the heart, the pericardium is affected first. The Lingshu notes, "Therefore the pathogenic factors that intend to attack the heart must first attack the pericardium."7 Clinically the symptoms of pathogenic invasion of the pericardium are the same as if the heart was ill. If pathogenic heat attacks the heart, the symptoms are unconsciousness, delirium, etc. If pathogenic phlegm causes mental confusion, unconsciousness or mental disorder, it is known as "pathogenic phlegm obstructing the heart orifice."

2. Lung

The lung is situated in the chest, connects with the throat and opens into the nose. Its main physiological functions and indicators are: 1) dominating qi and controlling respiration; 2) dominating the dispersion and descent of qi; 3) regulating water passage; and 4) connecting externally with skin and hair. It also has an exterior and interior relationship with the large intestine.

Dominating Qi and Controlling Respiration
This function is composed of two aspects, dominating the qi (air) of respiration and controlling respiration. It is the organ where the respiratory air is internally and externally exchanged; clean qi from the environment is drawn in and exchanged for waste qi. The other aspect of the lung's function has a close relationship with the formation of collective (zong) qi which is the combination of essential qi transformed from water and food with the inhaled qi of the lung. Collective qi accumulates in the chest, then flows up to the throat to control respiration. Since all the blood vessels lead to the lung, collective qi is distributed throughout the body to nourish the tissues and organs in maintaining the body's normal functional activities. If the lung function is normal, there is an unobstructed circulation of qi, with even and harmonious breathing. If there is a deficiency of lung qi, there will be feeble respiration, uneven breathing, weak speech, lassitude, etc.

Dominating the Function of Dispersion and Descent
The function of dispersion and descent involved the distribution of qi, blood, and body fluid to the zang-fu organs, the channel-collaterals, muscles, skin, and hair. Descending function means that lung qi is clear and descends. The lung is situated in the upper jiao (thoracic cavity) and its qi normally flow downward. If lung qi fails to descend and instead ascends, then the qi will pool together in the lung and be manifested by stuffy chest, cough, asthma, etc.

The two functions of dispersion and descent, although opposite to each other, act in unison. If the dispersing function is not normal, the lung qi will not flow downward and vice versa. Harmonious, downward flowing of lung qi allows for an unobstructed respiratory tract, uniform breathing, and provides a normal exchange of air in the lung. In this was the lung can distribute qi, blood, and body fluid to the entire body, transport waste water down to the urinary bladder, transform it into urine and excrete it.

In pathology, the two functions of dispersion and descent affect each other. If external pathogenic factors attack the exterior of the body, then the lung qi fails to spread. This leads to pathological changes like cough and asthma due to the failure of descending lung qi. If pathogenic phlegm obstructs the lung, it will bring about an abnormal flowing of lung qi leading to pathological changes such as cough, fullness of chest, and gurgling with sputum.

Dominating the Skin and Hair and Regulating Water Passages
Here the skin and hair represent the entire body surface including skin, sweat gland pores, and hire which act as a barrier against the invasion of exogenous pathogenic factors. In this way the lung is understood to have a close connection with the skin and hair. Through the dispersing function of the lung the essentials of food and water are transported to the body surface in order to nourish the skin, hair, and muscles. The lung also spreads defensive (wei) qi to the body's surface, "warms the tissues between the skin and muscles, replenishes the skin, nourishes the muscles, and regulates the opening and closing of the pores." Therefore the lung has the ability to protect the organic body by defending against the invasion of exogenous pathogenic factors.

Pathologically there is an mutual influencing relationship between the lung, and skin and hair. For example, the invasion of exogenous pathogenic factors proceeds from the skin and hair to the lung. The manifestations are aversion to cold, fever, nasal obstruction, nasal discharge, cough, or even asthma. These are signs of the lung's failure to spread defensive qi to the body surface. If lung qi is weak and deficient, defensive qi is not dispersed and the essential nutrients to the skin and hair are not distributed. This not only causes rough skin and dry hair, but also hypoactivity of the defensive qi.

The organic body is easily attacked by external pathogenic factors. Defensive qi controls the opening and closing of the pores. When there is lung qi deficiency the body surface will be weak and manifests the symptom of spontaneous sweating. If external pathogenic cold attacks the body's exterior the lung will lose its function of dispersing and descending and the pores will close not allowing the formation of sweat.

Regulating the water passages means that the lung regulates water circulation and excretion, and keeps the water passages clear. The lung's dispersing function circulates throughout the body the nutrients which have been removed from food and water. Part of the fluid is discharged as sweat and by the descending function of the lung. Another part of the fluid is continually sent down to the kidney and then, by the qi function of the kidney, sent to the urinary bladder to be discharged. Thus the lung is also known as the "upper source of water."

Opening into the Nose
The nose is the gateway of respiration. Clear, unobstructed nasal breathing and smelling rely upon the good functioning of the lung qi. Since the nose is the opening of the lung, it will also be a passage for the invasion of external pathogenic heat which may attack the lung. Pathologically the lung also has a close relation with the nose. For example, if external pathogenic wind and cold block the lung, it will cause a dysfunction of lung dispersion manifested by stuffy nose, nasal discharge, dull olfaction, etc. If pathogenic heat accumulates in the lung there will be nasal discomfort caused by coarse breathing or dyspnea. In treating this condition, the dispersing method with pungent medicinal herbs is used to act on the lung and nose. Acupuncture stimulation is applied on ear acupoint "lung" to treat nasal polypus, chronic rhinitis, etc. The above-mentioned facts demonstrate the close relationship between the lung and the nose. The throat is also a gateway of respiration, and a vocal organ. The lung channel passes through the throat, so smooth qi flow and a clear voice are directly affected by the functions of lung qi. Hence when there is a pathological change of the lung, it will cause hoarseness of voice, sore throat, or other pathological changes.

3. Spleen

The spleen is located in the middle jiao (abdominal cavity). Its main physiological functions and indicators are: 1) governing transportation and transformation; 2)controlling blood; 3) dominating the muscles and four limbs; 4) opening into the mouth, and lip complexion. The spleen has an exterior and interior relationship with the stomach.

Governing Transportation and Transformation
This function includes the transportation and transformation of water, and of essential nutrients.

If the spleen's transportation and transformation functions are sound then the functions of digestion, absorption and transportation will work normally. Otherwise, abdominal distention, diarrhea, lassitude, emaciation, malnutrition, and other symptoms may occur.

The spleen is also involved in water metabolism. When the spleen transports nutrient substances, it simultaneously distributes water to every tissue of the body carrying out its functions of nourishment and moistening. From the spleen, water is also sent down to the kidney and excreted from the urinary bladder. The whole process of distribution and metabolism of water is jointly accomplished by the lung's dispersing and descending functions and the spleen's transportation and transformation functions. If the spleen fails to transport and transform the water it will lead to various pathological changes. If water accumulates inside the body, it will turn into an inflammatory mucus (phlegm-humor); if it is retained in the skin and muscle, it becomes a swelling (edema); if the water retention is in the intestines, it will cause diarrhea; if it is in the abdominal cavity, it will result in serious fluid accumulation (ascites). In the Suwen it says, "...various kinds of diseases caused by dampness with swelling and fullness belong to the spleen."8

Since the functions of transportation and transformation of essential nutrients as well as water are interrelated, their pathological manifestations often accompany each other.

Controlling Blood
The spleen regulates blood circulation inside the blood vessels. If there is a qi deficiency in the spleen, then its function of controlling the blood is lost and the blood flows outside of the vessels. This is evidenced by various hemorrhagic symptoms and diseases, such as chronic uterine bleeding.

In order to control the blood, the spleen uses ying (nutrient) qi, a form of blood qi, which it produces. Qi behaves as the "commander" of the blood and, at the same time, conserves the blood. Therefore the hemorrhagic symptoms and diseases caused by the failure of spleen controlling blood are actually the results of qi failing to conserve blood.

Dominating the Muscles and Four Limbs
The spleen transports and transforms nutrient substances to nourish the muscles. If this function is normal, there will be sufficient nutrition. Any abnormality of transportation and transformation will certainly affect muscle tissue quality. The Suwen records, "The spleen is in charge of the muscles."9

The normal movements and functions of the four limbs are also closely related to spleen qi. When there is sufficient spleen qi, the yang qi distributes ample nutrient substances all over the body so that the muscles are well nourished and the four limbs are strong and able to move freely, Otherwise if the spleen fails to transport and transform the yang qi and nutrient substances, there will be malnutrition of the muscles characterized by muscular atrophy, weakness of the four limbs, etc. Therefore, building up the spleen is the usual clinical treatment for wei syndromes of the four limbs.

Opening into the Mouth and Lip Complexion
The appetite and sense of taste are closely related to the transportation and transformation functions of the spleen. If these functions are healthy, then there will be good appetite and normal sense of taste. If those functions are abnormal, there will be a lack of appetite. A greasy and sweet taste in the mouth is caused by damp obstruction in the spleen. In the Suwen it says, "Spleen qi is in communication with the mouth, and when the spleen functions harmoniously, the mouth will be able to taste the flavors of the five cereals."0

Since the spleen dominates the muscles and opens into the mouth, the strength or weakness of the transporting and transforming functions are reflected in the lips. If the spleen qi is not healthy, those functions will be abnormal, a condition which is characterized by yellowish and lusterless lips.

4. Liver

The liver's main physiological functions and indicators are: 1) storing blood; 2) creating unrestrained conditions for qi; 3) controlling the tendons and the luster reflected in the nails; and 4) opening into the eye.

Storing Blood
The liver stores blood and regulates the volume of blood circulation according to the needs of various tissues and organs. During rest the amount of blood required by the body decreases and the surplus is stored in the liver. During vigorous activity blood is released from the liver to increase the volume of circulating blood. As Wang Bin's Annotations on the Suwen notes, "The liver stores blood, the heart circulates blood. When the body moves blood circulates in the channels, when at rest it flows back to the liver."1 If the liver's blood storage function is abnormal, there will be an affect on normal body activities causing hemorrhagic diseases. For example, if liver blood is deficient the following problems may appear: the symptoms of vertigo, contracture of spasm of muscles and tendons, impairment of flexion and extension of limbs or scanty menstruation and amenorrhea.

Promotion of Unrestrained Conditions for Qi
Liver qi possesses the function of regulation. It is responsible for the ascending, descending, and harmony of bodily qi. If the body's qi activity is harmonious and its ascending and descending are normal then the internal organs will continue their normal physiological activities. This function of the liver involves the following aspects:

1) The liver harmonizes the emotions. Traditional Chinese medicine considers that the normal or abnormal function of an unrestrained and free flowing qi is directly related to emotional activities, and that the mental state is not only dominated by the heart but also the liver. When qi activities are normal, the body has a harmonious circulation of qi and blood, an easy mind and happy emotions. If there is a dysfunction of qi's free flow, it will directly affect the individual's emotional state. For example, liver qi stagnation will give rise to stuffiness and fullness of the chest, unhappy feelings, hypochondriasis, or even mental depression, crying, irregular menstruation, etc. If there is hyperactivity of the liver qi, there may be irritability, anger, insomnia, dream disturbed sleep, dizziness, vertigo, a ringing in the ear (tinnitus), or deafness. Any sudden change in the normal pattern of the emotions, especially great anger or mental depression, can affect and free flowing and spreading function of liver qi resulting in the pathological changes of liver qi stagnation.

2)Liver qi regulation can assist the ascending function of the spleen and the descending function of the stomach. This also involves bile secretion. Bile is necessary for the digestion of food and drink. If liver qi loses its harmonious flowing activities, it will affect the digestive function of the spleen and stomach and the excretion of bile, leading to the pathological symptoms of jaundice and bitter taste. It is very common that patients with stagnation of liver qi may not only have symptoms such as distension, pain in the chest and hypochondriac regions, anxiety, and anger, but also belching due to the failure of the stomach qi to descend and diarrhea caused by the dysfunctional ascending of spleen qi. The former is known as "liver qi affecting the stomach," and the latter as "disharmonious conditions between the liver and the spleen."

Controlling the Tendons and the Luster Reflected in the Nails
The tendons, fascia, and ligaments of the body all rely on the nourishment of liver blood. The movements of limbs and joints are not only the result of tendon flexing but are also related to the strength or weakness of liver blood. Only if liver blood is ample, can it nourish and supplement the tendons to continue the normal movements of the limbs. If the liver blood is insufficient and fails to nourish the tendons, the patient might experience symptoms such as tremors of the hands or feet, numbness of the limbs, or even difficulty in flexing and extending the limbs. If pathogenic heat exhausts the body fluid leading to the consumption of blood, then this will cause convulsion,, opisthotonos and lockjaw (trismus). As the Suwen notes, "various kinds of wind diseases causing the eyes to state upwards, twitching, dizziness, and vertigo, belong to the liver."2

It is said that, "Nails are the remains of the tendons,"3 The dryness or moisture of the nails can reflect the sufficiency or insufficiency of liver blood. When liver blood is plentiful the tendons are supple and the nails appear hard and moist. If liver blood is insufficient and incapable of nourishing the tendons, then the nails may be thin, soft, brittle, and pale. The Suwen records, "The liver communicates with the tendons. The health of the liver is reflected in the luster of the nails."4

Opening into the Eye
The essential qi of the five zang and six fu organs flows upwards to nourish the eye. Thus those organs, especially the liver, have a close relationship with the eye. The liver's function of storing blood nourished the eye as its channel travels upwards connecting to the eye system. In the Suwen it says, "Liver qi is in communication with the eyes, so the eyes will be able to distinguish the five colors."5 Thus an abnormality of liver function can affect the eyes. If the liver blood is insufficient, there will be a dryness of the eyes, blurred vision, or night blindness. If pathogenic wind-heat attacks the liver channel, redness, swelling and pain in the eyes will be the symptoms. If the liver fire flares up, conjunctivitis may occur. If liver yang is in preponderance, dizziness and vertigo occur. Liver wind stirring up produces convulsions with the eyes staring upwards.

5 Kidneys

The main physiological functions and indicators of the kidneys are: 1) storing essence, controlling human reproduction, growth and development; 2) controlling water metabolism; 3) receiving qi; 4) producing marrow, filling up the brain, controlling the bones, manufacturing blood and influencing hair luster; 5) opening into the ear, perineal ante-tract and perineal post-tract; 6) connects with the urinary bladder to which it is connected from the exterior and the interior.

Storing Essence, Controlling Human Reproduction Growth and Development
Essence is defined as the basic substance both constituting the human body and maintaining its functional activities. As described in the Suwen, "Essence is the foundation of the human body."6 Essence consists of two parts: congenital essence inherited from the parents and acquired essence transformed from food.

Essence is stored in the kidney and is known as kidney qi. It greatly influences the ability of reproduction, growth, and development. According to the Suwen:

At the age of fourteen, a woman will begin to menstruate. Her ren channel becomes unobstructed, and the qi of her chong channel is replete. This is why her menstruation becomes regular and she is able to conceive.... At the age of forty- nine, a woman's ren channel becomes deficient, the qi of the chong channel becomes weakened and scanty, sexual energy becomes exhausted, and menstruation stops with the result that her body becomes old and she is no longer able to conceive.7

In reference to men, it continues:

As to a man.... At the age of sixteen, his kidney qi becomes even more abundant, he begins to have sexual energy and is full of semen that he can ejaculate. When he has sexual intercourse with a woman, he can cause conception.... At the age of fifty-six the liver qi begins to weaken, the tendons become inactive, sexual energy begins to run out, the semen becomes inadequate, the kidney becomes debilitated with the result that all parts of the body begin to grow old. At the age of sixty-four his hair and teeth are gone.8

Thus, according to traditional Chinese medicine, kidney qi plays an essential role in the function of reproduction, growth, and development. If this function is abnormal, infertility, infantile underdevelopment, maldevelopment, weakness of bone development, etc. will manifest.

Kidney essence is classified as yin, while qi is yang. Known as kidney yin and yang, they both restrict and depend on each other in order to maintain a dynamic physiological balance. If this balance is disrupted, pathological changes of hyperactivity or hypoactivity of kidney yin and yang will occur.

Clinically, a kidney yin deficiency may be manifested soreness, aching and weakness of the lumbar region and knees, blurred vision, poor memory, etc. A yin deficiency leading to blurred vision, poor memory, etc. A yin deficiency leading to yang preponderance will produce tidal fever, night sweating, dizziness, ringing in the ear(tinnitus), spermatorrhea, and sexual dreams. Kidney yang deficiency decreases the warming function of the kidney bringing on the symptoms of lassitude, coldness and pain in the lumbar region and the knees, cold extremities and frequent urination, leading to pathological conditions such as inadequate reproductive ability, impotence, premature ejaculation and coldness of the uterus. If a certain degree of kidney yin or yang deficiency is reached then either may injure the other resulting in a loss of the body's dynamic physiological balance.

In addition, clinical manifestations such as frequent and clear urination, enuresis, incontinence of urine, spermatorrhea, premature ejaculation, etc. which show no heat or cold syndromes are considered to be a kidney qi deficiency. The clinical symptoms of dizziness, ringing in the ears, soreness and aching of the lumbar or knee region, infantile maldevelopment, etc, which demonstrate no clear cold or heat symptoms, are classified as kidney-essence deficiency.

Controlling Water Metabolism
The kidney plays an essential role in the distribution, regulation, and metabolism of water. As the Suwen says, "The kidney is the organ of water in charge of fluid."9 Water is received by the stomach, transformed and transported by the spleen. Par of the fluid is sent down by the descending function of the lung until it finally reaches the kidney and is divided by the qi activity of the kidney yang into two parts: clear and turbid. The useful clear fluid is sent back up to the lung a jin, and the turbid waste fluid flows down into the urinary bladder to form urine, which is excreted. The distribution of water is related to the functions of the stomach, spleen, small intestine, large intestine, lung, urinary bladder, and sanjiao, but they all rely on the warming and pushing function of kidney yang. If kidney yang is insufficient, this may lead to retention of water resulting in scanty urination, retention of urine or frequent urination, enuresis, etc.

Receiving Qi
The reception of qi is controlled by the kidney, which leads it downward from the lung. If kidney qi is adequate, and its functioning normal, then breathing is even and smooth. In a deficient state, uneven breathing, dyspnea, and asthma exacerbated by exercise will occur.

Controlling Bone, Producing Marrow, and Influencing Hair Luster
Nourishment of the bone structure requires marrow, a product of kidney essence. The term "marrow" includes the bone marrow and the spinal cord. The brain is known as the "sea of marrow." Sufficiency of this essence produces a well developed and functioning skeletal system. Inadequate essence, however, may lead to a variety of syndromes: a sore, aching, and weak lumbar region and knees, weakness or atrophy of the lower limbs, infantile maldevelopment, delayed closing of the fontanelle, etc. Furthermore, according to traditional Chinese medicine, "teeth are the remainder of bone." Poor nourishment by kidney essence also caused looseness and loss of teeth.

Essence and blood generate each other. Ample essence makes sufficient blood. Hair is nourished by the blood and rooted on the basis of kidney qi. Therefore luster, moisture, dryness, roughness growth and falling out of hair is related to the sufficiency of kidney essence. As the Suwen says, "The kidney is in tune with the bones, its prosperity is reflected in the luster and moisture of the head hair."0

Opening into the Ear, Perineal Ante-tract and Perineal Post-Tract
Auditory function is dependent on nourishment from the essential qi of the kidney. If that essence is sufficient, then keen hearing will result. Otherwise, there will be deafness and a ringing in the ears. The perineal ante-tract (including urethra and vagina) and post-tract (anus) have the action of reproduction and excretion through the function of kidney qi. Insufficiency will manifest as frequent urination, enuresis or scanty urine; for the reproductive organs there will be spermatorrhea, impotence, premature ejaculation, or infertility; bowel movements will be subject to either morning diarrhea or constipation.