As distinct from the Western medical concept of Spleen, this concept from Traditional Chinese Medicine is more a way of describing a set of interrelated parts than an anatomical organ. (See Zang Fu theory)

To differentiate between western or eastern concepts of organs the first letter is capitalized (Liver, instead of liver, Spleen instead of spleen). Because Traditional Chinese Medicine (TCM) is wholistic, each organ cannot be explained fully unless the TCM relationship/homeostasis with the other organs is understood. TCM also looks at the functions of the organs rather than fixed areas and, therefore, describes different organs that are not actually physical, like the Triple Burner (San Jiao). This also leads to controversy about the validity of TCM, which comes a lot from the difficulty of translating and lack knowledge about TCM concepts and Chinese culture. So, to avoid conflict and to keep an open mind, please realize that these notions evolved in a different culture and are a different way of viewing the human body.

The Spleen (Pi) is a Zang organ meaning it is a Yin organ. The other Yin, or Zang, Organs are the Lungs (Fei), Heart (Xin), Liver (Gan), Spleen (Pi), and Kidneys (Shen). Sometimes the Pericardium (Xin Bao) is included. Yin organs store, secrete, make, and transform Essence, Blood, Spirit, Qi, and Fluids. These nourish the body.

The Spleen is the origin of Blood. It rules transformation and transportation. The Spleen extracts essences from food and which later becomes Qi and Blood. It directs the ascending movement. The Spleen prevents extravasations of Blood. It dominates muscles. The Spleen assists with water metabolism. The Spleen opens into the mouth and is manifest on the lips. It also houses the Yi. The peak energy time for the Spleen is 9-11am. The fluid secretion is saliva.