While the relationship among the zang-fu organs is quite a complicated matter-s0 much so that it deserves to be devoted a lot of pages, yet, thanks to TCM's concise and brilliant summarization, it nay just as well be briefed in a broad outline.
In TCM, the zang - organs pertain to yin and are thought of as interior, while the fu-organs to yang and, naturally enough, as exterior. The interior- exterior relationship between then is formed by the connections of their meridians. This relationship as well as their physiological cooperation and pathological interaction can be clearly seen in the interrelations between the heart and the small intestine, the lung and the large intestine, the spleen and the stomach, the liver and the gallbladder and the kidney and the urinary bladder.
The heart and the small intestine are connected by the heart meridian and the small intestine meridian to form an exterior-interior relationship. Thus making the two pathologically related to each other. The excessive heart - fire tends to go into the small intestine, resulting in oliguria, burning pains during urination, etc. Conversely, the excessive heat in the small intestine may go upward along the meridian to the heart and cause internal hyperactivity of heart- fire. Leading to dysphoria, crinson tongue, oral ulceration and so on.
The lung and the large intestine forn an exterior-interior relationship by mutual connections of their meridians. The dispersing and descending functions of the lung help the large intestine to perform its transporting task. When the lung functions normally, the large intestine does well. Conversely, when the descending function of the lung qi do not wort well, it will affect the function of the large intestine in transportation, causing difficult bowel movements. On the other hand, loose stools and the stoppage of fu-qi may affect the descent of lung-qi, giving rise to asthmatic cough and chest distress.
Both the stomach and the spleen lie in the middle energizer and are connected by their meridians to forn an exterior-interior relationship. The stomach governs the reception,. while the spleen governs the transportation and transformation. The relationship between the two is that "the spleen conveys the body fluid for the stomach". If pathogenic damp attacks the spleea, it will injure the transporting and transforming functions of the spleen and affect the reception and the descending action of the stomach, resulting in poor appetite, vomiting, nausea and gastric distention. So the spleen and the stomach share out the work and cooperate with each other to jointly accomplish the task of the digestion, absorption and distribution of food. On the contrary, intemperance of food intake and dyspeptic retention of the stomach will bring about both the dysfunction of the stomach in descent but that of the spleen's transportation and transformation, causing such symptoms as abdominal distention, diarrhea.