The six fu-organs refer to the gallbladder, the stomach, the small intestine, the large intestine, the bladder and the triple energizer. The common physiological function of the six fu-organs is "to transmit and transform food", i.e. receiving and digesting food, absorbing the nutrients and excreting the waste. Since the six fu-organs should be clear in order to transmit and transform food, it is said that "the six fu-organs function to descend" and "the six fu-organs function well if they are unobstructed".