Fu Organs ( Small intestine, Gall Bladder, Stomach, Large Intestine, Urinary Bladder, Sanjiao )

1. Small intestine
The small intestine is situated in the abdomen, its upper end connected by the pylorus with the stomach and its lower end communicating with the large intestine through the ileocecum. Its channel connects with the heart, with which it is externally-internally related. Its main function is to receive and temporarily store partially digested food in the stomach. Further digesting the food and absorbing the essential substance and a part of the water in food, the small intestine transfers the residues with a considerable amount of fluid to the large intestine.

2. Gall bladder
The gall bladder is attached to the liver, with which its channel connects and with which it is externally-internally related. Its main function is to store bile and continuously excrete it to the intestines to help digestion. This function of the gall bladder is closely related to the function of the liver in promoting patency of vital energy. It is therefore said that the liver and gall bladder preside over the unrestraint and patency of vital energy.

3. Stomach
The stomach is situated in the epigastrium, its upper outlet connected by the cardia with the esophagus, and its lower outlet communicating with the small intestine through the pylorus. Its channel connects with the spleen, with which it is externally-internally related. Its main function is to receive and decompose food. That is to say, the stomach receives and temporarily stores the food mass coming from the mouth through the esophagus while partially digesting it and then sending it downward to the small intestine. That is why the function of the stomach is normal when its qi is descending and abnormal when its qi is ascending. The stomach and spleen act in co-operation and are the main organs carrying on the functions of digestion and absorption. It is said that the spleen and stomach are the source of health.

4. Large intestine
The large intestine is situated in the abdomen, its upper end connected with the small intestine by the ileocecum and its lower end communicating with the exterior of the body through the anus. Its channel connects with the lung, with which it is externally-internally related. The main function of the large intestine is to receive the waste material sent down from the small intestine and, in the process of transporting it to the anus, absorb a part of its fluid content and then turn it into feces to be excreted by the body.

5. Urinary bladder
The urinary bladder is situated in the lower abdomen. Its channel connects with the kidney, with which it is externally-internally related. Its main function is the temporary storage of urine and its discharge from the body when a certain amount has accumulated. This function of the urinary bladder is accomplished with the assistance of the qi (function) of the kidney.

6. Sanjiao
The channel of sanjiao connects with the pericardium with which it is externally-internally related. Sanjiao is not a substantial organ, but a generalization of part of the functions of some of the zang-fu organs located in different sections of the body cavity.

Sanjiao is divided into three parts:

1. Upper jiao (portion) (representing the chest) is a generalization of the function of the heart and lung in transporting qi and blood to nourish various parts of the body. It is like an all-pervading vapour.
2. Middle jiao (portion) (representing the epigastrium) is a generalization of the function of the spleen and stomach in digesting and absorption. This may be compared to soaking things in water to cause decomposition and dissolution of substances.
3. Lower jiao (portion) (representing the hypogastrium) is a generalization of functions of the kidney and urinary bladder in controlling water metabolism as well as storage and excretion of urine. It is like an aqueduct, a pathway for the flowing of water.