THEORY OF ZANG-FU ORGANS 

There are six zang organs and six fu organs. Zang fu organ theory is essentially the Yin-Yang, holistic, interconnected relationship of the organs.
Because the ancient sages of TCM did not, as a routine practice, dissect or conduct invasive internal surgical procedures, the protocol of zang fu organ theory was used as a way of explaining how external signs (a pale face, for example) reveals what’s going on internally (Spleen Qi deficiency, for example).
In short, zang fu organ theory can be summed up as such: the human body is a holistic, integrated microcosm of the universe. And all its tissues and structures are organically connected.