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What is Qi in Chinese Medicine



1. The Concept of Qi

What is meant by Qi? The concept of Qi is based on the ancient Chinese initial understanding of natural phenomena. That is, Qi is the most basic substance of which the world is comprised. Everything in the universe results from the movements and changes of Qi. This concept was introduced into TCM and became one of its characteristics. After a comprehensive survey of the statements on Qi in TCM documents, we have come to the conclusion that the meaning of Qi in TCM has two aspects. One refers to the vital substances comprising the human body and maintaining its life activities, such as the Qi of water and food (food essence), the Qi of breathing (breathing nutrients) and so on. The other refers to the physiological functions of viscera and bowels, channels and collaterals, such as the Qi of the heart, the lung, the spleen and the stomach and so on. The Qi here referred to, is specifically the physiological functions of these viscera and bowels.

2. The Formation of Qi

The Qi in the human body is different in classification and formation. But, generally speaking, it has no more than two sources. One is the innate vital substance one inherits from one's parents before birth. The other is the food essence and fresh air one receives from air, water and food in the natural world. The materials obtained in the two ways above have to be processed and transformed by the viscera and bowels before becoming the Qi of the human body. The process for Qi to be formed is as follows The innate vital substance acted on by the kidney comes out of the gate of life (the portion between the two kidneys) and goes up to the middle warmer. There it combines with the food essence coming from the spleen and continues upwards until it combines with the fresh air inhaled by the lung. Finally it turns into Qi. It is easy to see from the above that the Qi of the human body is formed through the joint work of the kidney, the spleen, the stomach and the lung in combining the innate vital substance taken from one's parents, the food essence received from water and food, and the fresh air obtained from nature.

3. The Functions of Qi

Different kinds of Qi have different functions. Generally speaking, they can be summarized as follows:

1) Promoting Action

Qi is a sort of essence full of vitality. It can help activate the growth and development of the human body, promote the physiological functions of each viscus, bowel, channel, collateral, tissue and organ and speed up the formation and circulation of blood and the metabolism of body fluid as well. For example, if the above functions are weakened as a result of the deficiency of Qi (vital energy), the following will occur: late and slow growth and development of the human body or senilism; weakened functions of viscera and bowels, channels and collaterals, tissues and other organs; insufficient blood formation or stagnation in blood vessels; and disturbance in the metabolism of body fluid.

2) Warming Action

Nan Jing (Classic on Medical Problems) says: "Qi has a warming action." Qi is the main source of the heat needed by the human body. The body keeps its constant temperature mainly through the warming action of its Qi. A deficiency of Qi can cause lowered body temperature, intolerance to cold and cold limbs.

3) Defending Action

The defending action of Qi is shown in two aspects. One is to guard the surface of the skin against the exopathogen. The other is to combat the invading exopathogen so as to ward it off. When the defending function of Qi is normal, the exopathogen has difficulty in invading the body, even though it may obtain entry, it is not certain to cause any disease. If it does cause a disease, this disease is easy to cure. When the defending function of Qi becomes weaker, when the ability of the human body to fight the exopathogen is lowered, the body is easily invaded and diseases are caused. And what is more, these diseases are hard to cure.

4) Consolidating and Governing Action

By "consolidating and governing action", we mean that Qi has the ability to command, control and consolidate the liquid substances and organs in the abdominal cavity. This is done by:

a. Keeping blood flowing within, not extravasating out of; the vessels;

b. Controlling and adjusting the secretion and excretion of sweat, urine and saliva, and preventing the body fluid from escaping;

c. Consolidating and storing sperm and preventing emission and premature ejaculation;

d. Consolidating the organs so as to prevent them from descending.


The consolidating and governing action and the promoting action of Qi oppose each other and yet also complement each other. On the one hand, Qi has the function of promoting the circulation of blood, and the transportation and distribution of body fluid. On the other hand, it also has the function of controlling and adjusting the movement, secretion and excretion of liquid substances in the body. The coordination and balance of these two functions are essential for maintaining normal blood circulation and water metabolism within the body.

5) Promoting Metabolism and Transformation

"Qi hua" is a specific term in the science of TCM. It refers, in general, to various kinds of changes taking place in the body under the action of Qi. Specifically, it refers to the metabolism of fundamental substances, vital energy, blood and body fluid, and the transformations which can occur between them. For example, vital energy, blood and body fluid are formed in the following manner: ingested food is changed into food essence, and food essence is, in turn, transformed into vital energy, blood or body fluid, and these can then be changed into any one of the others according to the physiological need of the body. The waste from the eaten food and the products produced in the course of metabolism are changed, separately, into feces, urine and sweat which are ready to be removed from the body. All these are the specific manifestations of the action of the activity of Qi. The dysfunction of Qi in performing its action will affect the whole metabolism of the body. That is to say, it will affect the digestion, absorption, transformation and transportation of food: the formation, movement and transformation of vital energy, blood and body fluid; and the excretion of feces, urine and sweat; thus causing various symptoms associated with abnormal metabolism. In short, the process in which Qi performs its functions is the process in which the substances in the body are metabolized, and in which the substances and energy are transformed.

Although the above five functions of Qi are different, they enjoy close cooperation and mutual support.

4. The Movement of Qi

The various functions of Qi are all performed by its movement. TCM calls the movement of Qi as "functional activities of Qi". Different types of Qi move in different ways. Theoretically, however, we can put them in four basic ways: ascending, descending, exiting and entering. Ascending refers to the movement from below; descending, from above; exiting, from the interior; and entering from the exterior. These movements of Qi are vital to life. Once they stop, life comes to an end. They are not only seen in promoting and activating various kinds of physiological activities in the human body, but also seen in motivating the physiological activities of the viscera and bowels, channels and collaterals, tissues and other organs. For example, while the lung performs its function, exhaling is exiting, inhaling is entering, dispersing is ascending and keeping the inspired air flowing downward is descending. Of course, this doesn't mean each organ functions in all four types of movement. Some organs only function in a particular one. For instance, it is appropriate for the Qi of the spleen to ascend and the Qi of the stomach to descend. However, in view of all the physiological activities of the body, the four movements of Qi have to be coordinated and balanced. Only in this way can the physiological functions of the human body remain nor-~a1 In TCM, the physiological state in which the four basic movements of Qi are coordinated and balanced is called "harmonious functional activities of Qi". When they are uncoordinated and unbalanced it is called "disharmonious functional activities of Qi". Because the movements of Qi differ, the disharmonious functional activities of Qi are shown in various ways. For example, over-ascending is known as "the abnormal rising of Qi"; not descending on time, "the non-descending of Qi"; not ascending on time or over-descending, "the sinking of Qi". Exiting too much because it is unable to be contained is known as "the escape of Qi", while an accumulation inside due to its being unable to exit is known as "the accumulation of Qi" or "depressed Qi", and even "closed Qi" when the accumulation is more severe. If Qi has difficulty in moving or its flow is even partially obstructed it is called "the stagnation of Qi". As to individual internal organs, the examples of the disharrn6-nious functional activities of Qi are as follows: the non-descending of the Qi of the lung, the sinking of the Qi of the spleen, the adverse rising of the Qi of the stomach, the nonconsolidation of the Qi of the kidney, etc.

5. The Classification of Qi

The Qi of the human body is classified into the following categories:

1) Inborn Qi

Inborn Qi is also called "primordial Qi" or "genuine Qi". It is the most important and fundamental of all.

(1) Formation

Inborn Qi comes mainly from the innate essence stored in the kidney. But it also depends on the supplement and nourishment of the acquired essence developed in the spleen and stomach. This is what The Acupuncture Therapy And The Relation Between Healthy Energy And Pathogen, a chapter of Miraculous Pivot, says: "The inborn Qi is received from heaven and combined with food essence to nourish the body."

(2) Movement

The inborn Qi commences from "the vital gate", the portion between the two kidneys, passes the triple warmer and circulates throughout the body. It goes inward to the five viscera and six bowels and outward to the muscles and skin, i.e., the superficial layer of the body. It goes everywhere and acts on all parts of the body.

(3) Functions

The inborn Qi has the functions of both activating growth and development and promoting the functional activities of

all the viscera and bowels, channels and collaterals, tissues and other organs. Therefore, the inborn Qi is the motivating power of the vital activities of the human body. Sufficient inborn Qi causes normal growth and development of the body and heal-thy and vigorous activities of all the functions of the body. Insufficient inborn Qi leads to late and slow growth and development, and reduces all physiological functions. This is indicated by lassitude, general debility and susceptibility to diseases.

2) Pectoral Qi

Pectoral Qi is the Qi stored in the chest.

(1) Formation

Pectoral Qi is a combination of the fresh air inhaled by the lung and the food essence derived by the spleen and stomach from water and grain.

(2) Movement

Pectoral Qi is stored in the chest and poured into the channels of the heart and lung just as Five Kinds of Flavor, a chapter of Miraculous Pivot, says: "It goes out of the lung and circulates through the larynx and pharynx. This is the reason why it exits when being exhaled and enters when being inhaled." The book Classified Canon compiled by Zhang Jiebin in 1624 A.D. says: "It goes down to the elixir field to be stored, and fills the Point Qijie of the yangming Channel from which it continues to go downward to the feet."

(3) Functions

Pectoral Qi, in the main, has two functions. One is that it flows through the respiratory tract to promote the respiratory movement of the lung and is involved in the loudness or softness of voice and words. The other is that it fills the heart channel to promote and adjust its beat, and to promote and adjust the circulation of blood and vital energy. It also exerts an influence on the warmth and activities of the limbs. Therefore, the manifestations of a deficiency of pectoral Qi are, often, the weakness of the functions of the heart and lung, such as shallow breathing, soft voice, abnormal heartbeat, slow blood flow, cold limbs, lassitude and moving with difficulties. In clinical practice, it is often by the pulsation on the apex of heart that TCM decides whether pectoral Qi is weak or not.

3) Nourishing Qi

Nourishing Qi refers to the Qi circulating within the blood vessels and having a nourishing function. As it flows through the vessels with blood, it has such a close relationship with the latter that TCM often mentions them in a combined way "nourishing blood". Compared with defending Qi, nourishing Qi belongs to yin, so it is also called "nourishing yin".

(1) Formation

Nourishing Qi comes mainly from the food essence transformed and transported by the spleen and stomach. This is why a chapter on Arthralgia-Syndrome of Plain Questions says: "What is nourishing 9i ? It is the essence of food and water."

(2) Movement

Nourishing Qi originates from the middle warmer and enters the channels by way of the lung. It circulates throughout the body along one after another of the fourteen channels.

(3) Function

Nourishing Qi has two main functions. One is to produce blood, that is, it flows into the channels through the lung and becomes a component of blood. The other is to nourish the whole body. That is, it goes up and down along the channels, circulatng round the body and thus providing nutrients for the physiological activities of all the viscera and bowels, channels and collaterals, tissues and other organs. So, a chapter on the Pathogens Attacking the Body of Plain Questions says: "Nourishing Qi secretes its fluid, which enters the channels and turns into blood, thus nourishing the limbs, the five viscera and the six bowe1s."

4) Defending Qi

Defending Qi is the Qi moving outside the conduits and having protective functions. Compared with nourishing Qi, it belongs to yang, so it is also known as "defending yang".

(1) Formation

Defending Qi also comes from the food essence transformed and transported by the spleen and stomach. It is characterized by braveness in defence. That is why a chapter on Arthralgia-Syndrome of Plain Questions says: "Defending Qi is a brave kind, which is produced by food and water."

(2) Movement

Defending Qi circulates not within but outside the channels. Being vaporized to the diaphragm and scattered in the chest and abdomen, it travels between the skin and flesh. In spite of circulating outside the channels, it still leans against the channels when moving.

(3) Function

Defending Qi has three functions. The first is guarding the surface of the body against exopathogen. The second is keeping a relatively constant body temperature by controlling the opening and closing of the pores and adjusting the excretion of sweat. The third is nourishing the viscera, bowels, muscles, skin and hair.

In addition, the circulation of defending Qi is associated with sleep. Man goes to sleep when defending Qi circulates in the interior of the body, whereas he wakes up when it circulates on the surface of the body.

When defending Qi is insufficient, the defending function of the human body is weakened, the exopathogen invades the body easily, and the disease is hard to cure. Abnormal circulation of defending Qi may cause sleep disorders. The longer defending Qi circulates on the surface of the hod y, the shorter the duration of sleep, while the longer it circulates in the interior of the body, the longer the duration of sleep.

Nourishing Qi and defending Qi have the same source. The former circulates within the channels, has the nourishing function and belongs to yin, whereas the latter circulates outside the channels, has the function of guarding the exterior of the body and belongs to yang. Only when they coordinate with each other can the opening and closing of the pores be kept normal, the body temperature constant, and the defending ability strong. When they can not coordinate with each other because of an attack by exopathogen, such symptoms as aversion to wind, fever and sweating will occur.

Extracted from "Basic Theory of Traditional Chinese Medicine"


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