The six fu-organs is a collective term of the stomach, small intestine, large intestine, gallbladder, urinary bladder, and triple energizer (sanjiao). They are primarily involved in the digestion and transmission of food and water. They transport, discharge but do not store, characterized by the functions of unblocking and descending. These organs take in and digest food and water, absorb the essence, transmit the residues after decomposition, and finally remove wastes from the body. They cooperate and work in sequence to fulfill their respective functions. The six fu-organs are not supposed to be filled with food, water, and wastes. Otherwise, disorders will occur. The dysfunction of their transforming and transporting will make it difficult to digest food and water and further convert these substances into essence. Moreover, it will be difficult to remove waste substances and turbid qi from the body. All of the above may cause disorders of the five zang-organs.