One of the five zang-organs. The liver is the organ that stores blood and can regulate the distribution of blood throughout the body. The nature of the liver is like wood, promoting free flow and smoothness (the term "smoothness" originally describes the unconstrained growth of trees with freely extending branches. In relation to the human body, when liver qi flows smoothly, qi and blood circulation are more comfortable. The smoothness of liver qi relies on its dispersing function. The dispersing function of the liver also aids in the transformation of spleen middle consumptive thirst and the distribution of spleen qi essence) and dislikes depression or stagnation, otherwise it is prone to cause liver qi stagnation disorders.

"The liver governs the design of strategy," indicating that the liver is also related to the activities of the central nervous system. In terms of emotions, the liver is associated with "anger." When subjected to mental stimulation, it is easy to produce symptoms such as irritability and head distension.

The liver also governs the movement of tendons (so-called "the liver governs the tendons") and is the "root of physical stamina" (enabling people to withstand fatigue). "The liver opens into the eyes," and many eye diseases need to be treated from the perspective of the liver.