The harmonious functions of the organs and various types of Qi rely partly on correct direction of Qi movement. Qi has to flow in the right direction: exiting-entering and ascending-descending.
Control respiration: inhale clear air Qi & exhale impure Qi.
Control the descending of Qi: send Qi downward to Kidneys & Bladder.
Controls the smooth flow of Qi in all directions, esp. upward.
Lungs & Liver balance each other (Lung Qi flows downward, and Liver Qi upward)
Control transformation of Water.
Impure Fluids flow downward & clear Qi flows upward.
Lung Qi descends to Kidneys. Kidney Qi ascends to Lungs.
Lungs send Qi down. Kidneys receive Qi.
Lung controls exhalation. Kidney controls inhalation.
Spleen sends pure Qi upward to Lungs & Heart.
Stomach sends impure Qi downward for further refinement.
Spleen controls transformation, Stomach controls receiving.
Therefore ascending of clear Qi and descending of impure Qi depend on ascending of Spleen Qi and descending of Stomach Qi.
Fire of Heart flows downward to meet Water of Kidneys. Water of Kidneys rises to nourish Fire of Heart.
Derangement of any of the above directions of Qi flow can cause problems.