First we will look at water metabolism from a Western physiology point of view. The Liver manufactures the components of the serum of whole blood. The spleen is the organ that removes old red blood cells (RBC) from circulation. Some now RBC arise here but most in the marrow of bone. The lymphatic system and the spleen are the source of white blood cells (WBC). The lymphatic system conducts fluid from the tissue interstices of the extrcellular matrix back into blood circulation. It also conducts phospholipids from the gut into blood circulation. The blood conducts sugars, amino acids and small peptides into general circulation from the gut. The lungs produce arginine-vasopressin that acts on the kidney nephron to alter water balance in the body. The mineral corticoids of the adrenal glands regulate water balance in the body via the kidney nephron. The liver produces angiotensinogen that assists in water balance via the angiotensin-renin-aldosterone system. The kidney produces rennin that assists in the regulation of water balance. The neuroendocrine system (hypothalamus-pituitary-endocrine organ) regulates all of the systems of the body. The blood carries oxygen, nutrients, wastes and coagulation factors to and from all parts of the body. The interstitial fluid bathes all the cells of the body. Interstitial fluid is derived from blood fluids and carries oxygen, nutrients, wastes and cellular products.
Next, we will look at water metabolism from the point of view of traditional Eastern physiology.
As different from the Western medical concept of distinct organ systems and their attendant unique physiologies, the concept of organ systems in traditional Chinese medicine (TCM) is more of a way to describe a set of interrelated parts with physiological, emotional and mental components. TCM is truly a wholistic paradigm.
Because TCM is holistic, each organ cannot be explained fully unless the TCM relationship as to rheostasis with the other organs is understood. TCM also looks at the functions of the organs rather than fixed areas and, therefore, describes different organs that are not actually physical, like the San Jiao (the 3 bowls of the body cavities as chest, abdomen and sacrum). This also leads to controversy about the validity of TCM, which comes from both the difficulty of translating and lack knowledge about TCM concepts and Chinese culture. One needs to keep an open mind, please realize that these notions evolved in a different culture and are a different way of viewing the human body. These concepts were developed over time some 4000 or more years ago into recent history.
The Kidneys (Shen) is a Zang organ meaning it is a Yin organ. The other Zang (Yin) organs are the Lungs (Fei), Liver (Gan), Spleen (Pi), and Heart (Xin). Sometimes the Pericardium (Xin Bao) is included. Yin organs store, secrete, make, and transform Essence, Blood, Spirit, Qi, and Fluids. These substances then nourish the body.
The Kidneys store the Essence (Jing) of the body and are considered the root of everything. The Kidneys govern water metabolism, reproduction, secretions and some brain functions. Fluid secretions by the Kidneys are urine, semen, and vaginal fluids. The kidney maintains the balance of the fluid and minerals in the body. Fluid in the body is responsible for transporting nutrients to organs and tissues, and to aid in getting rid of waste. The kidney plays an important part in both functions. The kidney either releases water or retains needed water. When the kidney is functioning well, urination is normal. When it doesn’t function well, the kidney could release too much, causing diseases like polyuria and frequent urination. When the kidney does not release enough, it can lead to oliguria and edema. In TCM there is only one Kidney which includes both left and right kidneys (left is Yin and right is Yang). The space between them is known in TCM as the San Jiao.
The other Zang organs involved with water metabolism in TCM are the Spleen, the Lungs and the San Jiao. The lungs are said to regulate water circulation. If the lungs are functioning properly, it is also able to spread water to the kidney and urinary bladder, thus smoothing the metabolism of water. If water does not go smoothly to the kidney and urinary bladder, it results in dysuria, edema, and phlegm-retention diseases. The spleen also absorbs and transports water. The Spleen is said to transform and transport water for use in the body. If the spleen cannot metabolize water properly and retains water, it results in edema, dampness, and diarrhea. From the spleen, water is also sent down to the kidney and excreted from the urinary bladder. Lastly, the San Jiao is said to be the pathway by which the fluid of the body is distributed.
Thus, it is readily appearant that in TCM problems with the origin of water metabolism involves more that just the kidneys. Edema is a serious result of the disfunction of many organs. The retention of Dampnes is more widely distributed in the population and is usually viewed as obesity or in the worst case some form of urinary dysfunction. Diarrhea tends to be more of a Spleen problem but may also be with kidney involvement. This is a very brief account of water metabolism from both perspectives, East and West. In all cases, the function of the organs is dependent upon adequate Qi and Yang within each organ. The liver plays a role here as being the master of Qi flow within the body. The Kidney is the ultimate source of Yang within the body. As you may understand, TCM is by no means an easy conceptual framework to comprehend, use and master.
Oriental Medicine Section