Zang - heart, liver, spleen, lungs and kidneys are the core of human life. Among them, the heart governs blood vessels, the lungs govern qi, the liver governs hair growth, the spleen governs transportation and transformation, and the kidneys store essence. They are all important organs of the human body. Especially the heart and kidneys are the most important ones. The heart is equivalent to the engine of life; the kidneys are the energy source of life. Therefore, once the heart and kidneys are damaged, you can imagine the consequences. In fact, no matter which one of the five internal organs is damaged, life will be threatened. This shows how important it is to maintain the five internal organs. However, the vitality of the five internal organs is not constant, but has a natural decline law. As recorded in the "Huangdi Neijing", starting from the age of fifty, one organ ages every ten years in the order of liver, heart, spleen, lung and kidney. For example, the sign of liver failure at the age of fifty is "unclear vision", the sign of heart failure at the age of sixty is "good sleep", the sign of spleen failure at the age of seventy is "deficiency of spleen", the sign of lung failure at the age of eighty is "good speech", the sign of kidney failure at the age of ninety is "empty meridians".
