According to traditional Chinese medicine, the kidney (Chinese: 腎: shèn) refers to either of the two viscera located on the small of the back, one either side of the spine. As distinct from the Western medical definition of kidneys, the TCM concept is more a way of describing a set of interrelated parts than an anatomical organ. In TCM the kidneys are associated with "the gate of Vitality" or "Ming Men". A famous Chinese doctor named Zhang Jie Bin (approximately 1563-1640) wrote "there are two kidneys, (kidney yin and yang), with the Gate of Vitality between them. The kidney is the organ of water and fire, the abode of yin and yang, the sea of essence, and it determines life and death." TCM overview The kidney (Shen) is a Zang organ meaning it is a Yin organ. The other Yin, or Zang, organs are the lungs (Fei), liver (Gan), spleen (Pi), and heart (Xin). Sometimes the pericardium (Xin Bao) is included. Yin organs store, secrete, make, and transform essence, blood, spirit, Qi, and fluids. Kidney main functions The main functions of the kidney are: storing essence (jing) and dominating human reproduction and development dominating water metabolism and the reception of qi from the air (Kong Qi) producing marrow to fill up the brain dominating bone manufacturing blood manifesting in the hair (on the head) opening into the ear and dominating the two lower yin (the anus and urethra) dominating anterior and posterior orifices. housing the Zhi (will-power) fluid secretions are urine, semen, and vaginal fluids. Storing essence and dominating development and reproduction The kidney's primary function is storing and controlling 'essence', or jing. Jing is the essence of qi and the basis for body matter and functional activities. There are two types of jing, congenital jing and acquired jing, which are stored in the kidney and known as kidney jing. Unlike qi, jing circulates in long cycles (seven years for females and eight years for males) governing developmental stages. The function of jing is to promote growth, development and reproduction, provide the basis for kidney qi, produce marrow, and provide the basis for jing, qi and shen (mind). Congenital jing comes from the parents and determines basic constitution; it cannot be altered, but it can be positively influenced by acquired jing. Acquired jing is produced from food by the spleen and stomach, stored in the kidney and circulated in the