These movements of Qi are vital to life. Once they stop, life comes to an end. They are not only seen in promoting and activating various kinds of physiological activities in the human body, but also seen in motivating the physiological activities of the viscera and bowels, channels and collaterals, tissues and other organs. For example, while the lung performs its function, exhaling is exiting, inhaling is entering, dispersing is ascending and keeping the inspired air flowing downward is descending. Of course, this doesn't mean each organ functions in all four types of movement.
Some organs only function in a particular one.
For instance, it is appropriate for the Qi of the spleen to ascend and the Qi of the stomach to descend. However, in view of all the physiological activities of the body, the four movements of Qi have to be coordinated and balanced. Because the movements of Qi differ, the disharmonious functional activities of Qi are shown in various ways. It is the most important and fundamental of all. But it also depends on the supplement and nourishment of the acquired essence developed in the spleen and stomach.