One of the central pillars of Traditional Chinese Medicine (TCM) the theory of Zang Xiang.  The ancient Chinese scholars believed that there are five ruling organs in the body: Heart, Lungs, Liver, Spleen and Kidney.  Each organ corresponds to one of the five Chinese elements and by combining the two theories we can track their functions and the progress of diseases.  The theory of Zang Xiang also studies the psyological, pathological and emotional conditions of organs and their external manifestations. Their interconnectedness and affects on other aspects of the body such as, vital substances (blood, bodu fluid and qi), tissues, emotions and senses.

The Zang organs only store pure and refined substances which they receive from the Fu-organs.  The five organs are solid, can hold qi and refined essences but do not discharge them.

The Fu organs, gall bladder, stomach, small intestine, large intestine, urinary bladder and san jiao (the empty body cavities).  They transform and refine food and drink to extract nutrients.  The Fu organs are constantly filled then emptied, thereby eliminating waste.