The Yin and Yang Theory

The Yin-Yang theory considers the normal vital activities of the human body to be the result of the relative balance between Yin and Yang. In traditional Chinese medicine, the physiological functions of the organs are inseparably related to Yin and Yang. 

Since imbalance and fluctuation of Yin and Yang are considered the basic causative factors of disease occurrence and development, treatment must readjust Yin and Yang to their basic state of relative balance.

In medical treatment, the theory of Yin and Yang is not only used to decide the principles of treatment. This theory is also generally applied to the properties, flavor and action of Chinese herbal medicine as a guide to the clinical administration of herbs. For example, herbs with cold, cool or moist properties are classified as Yin and drugs with the opposite properties are classified as Yang. Herbs with sour, bitter, or salty flavors are Yin, while those with pungent, sweet, or insipid flavors are Yang. Herbs with an astringent or descending action are Yin and those with an ascending and dispersing action are Yang. In clinical treatment, we should determine the principles of treatment based on an analysis of the Yin and Yang conditions present in terms of their difference Yin-Yang properties and actions. The goal of clinical treatment is to restore healthy Yin-Yang properties and actions. The goal of clinical treatment is to restore a healthy Yin-Yang balance in the patient.

The Five-Element Theory

The five-element theory states that everything in the universe is governed by five natural elements. These elements are wood, fire, earth, metal, and water. In this theory, each of the elements is associated with a particular organ. The wood element is associated with the liver; the fire element is associated with the heart; the earth element is associated with the spleen; the metal element is associated with the lungs; and the water element is associated with the kidneys. To find out what element problem it is, we will ask many detailed questions to gain clues related to the person’s body constitution and imbalances so that we can treat the problems accordingly.

The Eight Guiding Principles

As well as the five elements theory, we also use the eight guiding principles to help analyse and differentiate between the imbalances in the body. Even though there are eight guiding principles, they actually exist as four pairs of polar opposites.

  • Cold/Heat this principle is used to find out what the overall energy of the patient is. Conditions are characterised as being “cold” or “hot”, with cold conditions having symptoms such as a slow metabolism and chills, while hot conditions may have symptoms such as a fast metabolism, high fevers, and feelings of heat within the body. 
  • Interior/Exterior this principle is used to describe the patient’s symptoms according to where the problem is located. Exterior conditions are usually short lasting and are caused by germs entering the superficial area of the body. Interior conditions result from germs that enter deeper and affect the organs, brain, spinal cord and bones. 
  • Deficiency/Excess this principle is used to describe the nature of an illness. A deficient condition is the lack of blood, energy, and body fluid. An excess condition is where the body has too much of something. 
  • Yin/Yang all of the above principles and conditions are categorized according to the dominance of the Yin or the Yang. 

The combination of the above principles indicates the nature of the body. Health problems are diagnosed using combinations of the eight guiding principles.

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.

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 Channels and Collaterals Theory

The theory of channels and collaterals is an important component of the theoretical system in traditional Chinese medicine. It covers the physiological functions and pathological changes of the channels and collaterals, their interrelations with the zang-fu organs, and is essential in guiding clinical practice, especially acupuncture treatment.

1. Channels and Collaterals System (Meridian System)

The system of channels and collaterals constitutes the twelve regular channels, the eight extra channels, the fifteen collaterals, the twelve divergent channels, the musculo-tendinous and cutaneous regions of the twelve regular channels.

2. Channels and Collaterals Functions

(1) Physiologically, the channels and collaterals are considered to be a series of connecting passages through which qi and blood circulate to regulate the functions of the zang-fu organs, tissues, and sense organs. These passages also conduct the sensations and reactions (deqi) of acupuncture treatment.

The five zang and six fu organs, four limbs, nine orifices, skin muscles, vessels, and tendons, although having their respective physiological functions, also maintain the harmonization and uniqueness of interior, exterior, upper, and lower parts of the body as a united and organic entity. This interconnection and organic combination relies upon the function of the channels and collaterals system.

All the tissues and organs of the human body need the nourishment of qi and blood in order to keep their normal physiological activities. The distribution and circulation of qi and blood throughout the body to nourish the zang-fu, tissues, and organs and to resist exogenous pathological factors depends on the transportation and conduction of the channels and collaterals. As the Lingshu records:

The channels and collaterals are the passages through which blood and qi flow to nourish yin and yang, to moisten tendons and bones, and to lubricate the joints.

(2) Pathologically, channels and collaterals are the pathways through which the exogenous pathological factors are transmitted and their channels reflected. In the Suwen it is noted:

When pathogenic factors invade the skin and the pores are open they enter the collaterals. When the collaterals become full, the pathogenic factors will move into the channels. When the channels are full, the pathogenic factors transmit to and reside in the zang and fu organs.

The interior and exterior, upper and lower parts of the body form an integrated entity through the connecting network of channels and collaterals. So under pathological conditions every part of the body will affect the rest via the channels and collaterals. The channels and collaterals are not only the passages of disease transmission, but can also reflect pathological changes. Namely, the diseases of the zang-fu organs can be reflected on the body surface, especially in certain areas or at certain points, through the transmission of channels and collaterals.

(3) In diagnosis, channels and collaterals have certain running courses that connect with the zang-fu organs. They also reflect pathological changes on the body surface. Therefore clinical diagnosis can be made according to symptoms that are related to those courses and their respective zang-fu organs.

(4) In treatment, the theory of channels and collaterals is extensively used in clinical treatment for different branches of traditional Chinese medicine. Treatments using traditional medicinal herbs are based on their main actions related zang-fu organs and channels. In the practice of acupuncture, the theory of channels and collaterals is the basis of all treatment and clinical practice. Point selection and prescription combinations are all made on this basis. By stimulating a certain point or area on the body surface the physiological functions of the channels and collaterals are aroused. This action is achieved by propagating sensation through the channels. Without this sensation it is hard to achieve a therapeutic effect.

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