In Traditional Chinese medicine, each of the five elements has a pair of yin and yang organs. The yin organs meridian has a downward flow of energy and the yang upward. An imbalance of the yin-yang ratio can cause illness. Every individual needs to find this balance depending on their own constitution, climate, season, occupation and even emotional environment. If in perfect health, the individual should be able to adapt to any of the inevitable changes of life.
Pressure point is based on the theories of yin (negative) and yang (positive), and of the five external elements, which are metal, wood, water, fire, and earth. The yin and yang theory holds that every phenomenon in the universe consists of these two complimentary and yet opposing forces. According to this theory, the human body is also made up of yin and yang elements.
Like this diagram of Five Element Theory. Used it as part of my dissertation on Medical Qigong and Transplant. In Chinese medicine, a human body is divided into five systems: wood, fire, earth, metal, and water. Human organs and tissues correspond to the five elements. The body’s five systems not only automatically self-regulate according to the laws of yin and yang but also coordinate with the five elements from the outside world in order to achieve health.