The lung governs descending, and the passage of water is opened, so that water can flow down to the kidney. Kidney governs body fluid, which evaporates from kidney yang, so that the body fluid in the middle is clear and reaches the lung, and the function of body fluid metabolism is completed by the transport of spleen yang. Dysfunction of lung, spleen and kidney, and dysfunction of an organ will cause water retention and edema. Lung governs breathing, and kidney governs qi intake. Both viscera have the function of maintaining the ascending and descending of human qi.