Qi, Blood and Body Fluid

Source qi (yuanqi) known as the qi of the kidney, being inherited from the parents and related to reproductive function, is referred to as congenital qi.

Clean qi (qingqi) and qi from essence of food, obtained respectively from the atmosphere and food after birth, are known as acquired qi. The two kinds of qi meet in the chest forming essential qi (zongqi) whose main function is to nourish the heart and lung and promote their functions of dominating blood and vessels and performing respiration. Both nutrient qi (yingqi) and defensive qi (weiqi) are formed from essential substances in food. The former circulates in the vessels and supplies mainly the viscera. The latter circulates outside the vessels and is mainly distributed in the muscles and skin to warm and nourish the subcutaneous tissues, control the opening and closing of the pores and defend the body against exogenous etiological factors. Hence the name.

Zang-fu and channels and collaterals, acted upon by both congenital and acquired qi, function in a way known as the qi of zang-fu and channels and collaterals. Examples are the qi of the heart, lung, spleen, kidney, stomach, channels and collaterals. The so-called "arrival of qi" in acupuncture therapy means that the needling has produced its effect with the calling into function of the channels and collaterals.