Three yin and three yang: three yin refers to Taiyin, Shaoyin and Jueyin channels. Three yang refers to Taiyang, Yangming and Shaoyang channels. They are opposite in function. The three yin channels govern the interior: heart,  liver, spleen, lungs and kidney. The three yang channels govern the superficial: bile, stomach, large intestine, small intestine, gallbladder and san jiao (triple energizers) .

1. There has always been a close relationship between man and nature. The basics of life are yin and yang.
2. Everything between the earth and heaven, the nine continents. . . .
3. Man's nine orifices, five internal organs, and twelve joints are closely related to the climate.
4. Yin and yang in heaven produces the five elements on earth. And the five elements on earth correspond to the three yin and three yang in heaven.
5. If people often transgress the law between man, heaven, and earth, evil qi will harm their body and will affect their life span.
Learn more about the theory of Chinese medicine, please read Relationship Between Structure and Function.