As a refined substance, Qi is very active, restless, and often invisible. Qi moves through organs or viscera, meridians, and especially the cavity spaces between the organs. There are four movements of Qi: ascending, descending, exiting, and entering through circulation channels or radiation. By mixing, impacting, and colliding, Qi boosts the physiological functions of the organs, such as the activities of the viscera and meridians. Qi’s motion is concretely reflected by various physiological activities in the meridians, viscera, and spaces. These include the functions of a single viscus and the functions of several related viscera. For example, the Lung’s inhalation is Qi entering, its exhalation is Qi exiting, and its dispersing is Qi ascending and descending. In digestion and absorption, the Spleen sends up (ascends) the clear substances and the Stomach sends down (descends) the turbid substances.
Ascending and exiting pertain to Yang; descending and entering, Yin. Their contradictory motions are the unity of opposites. All types of Qi circulations have their own forms. Generally, the motion of visceral Qi depends on physiological characteristics and the location. The five Zang-viscera, which store essential substances, are in charge of ascending; the six Fu-viscera, which transform and transmit food and its waste, are in charge of descending.
But each individual Zang or Fu viscus alone has a particular Qi movement pattern. For instance, the Lung is mainly descending, but has all four patterns. The Heart is mainly descending, but is also ascending. The Spleen is mainly ascending. The Stomach is mainly descending. The Kidney and Liver, located in the Lower Jiao, have only two styles — typically ascending, but also descending. The Zang and Fu organs, through their various patterns of Qi movement, coordinate to form a special system for regulating Qi activity.
The four movement patterns can transform into each other. When Qi ascends to the supreme point, it begins to descend. When Qi descends to the lowest point, it begins to ascend. When Qi disperses outward (exiting) to a certain degree, it begins to change itself inward (entering), and vice versa.
According to new research and practical clinical experience, the most important opposite Qi movements are called “Great Revolution” 
, which refers to the Ren 
and Du 
Meridians vertically; and “Small Circulation” 
, which refers to the three Jiaos horizontally . The most important movement is in the area of the Bladder Meridian within the big space between the spine and the viscera in the back, which is called the Fourth Jiao or Wai Jiao. Qi from every viscus meets, mixes, impacts, collides, and interacts there . About 2000 years ago, the famous medical sage Zhang Zhongjing strongly emphasized the importance of this area. The body’s health largely depends on the movement of Qi in this area.
Qi movement disorders, such as obstructed Qi flow (often in the Liver), are called “stagnation of Qi.” When Qi either ascends in a weak manner or descends with too much vigor, it is called “sinking of Qi.” When Qi ascends too strongly or does not descend strongly enough, it is called “adversity of Qi.” If an excessive amount of Qi leaves the body, it is called “exhaustion of Qi.” For Qi’s failure to exit, the body is called “depression of Qi” or “blockage of Qi.” In many cases, Qi stasis is the direct source of pathology.
Qi circulation is the vital activity of the body. Once it becomes disordered, there will be illness; once it stops, it is the end of the vital activity of life.