CHAPTER 5 Overview of Traditional Chinese Medicine: The Cooking Pot Analogy
In Nei Jing Su Wen, the 2000-year-old seminal classic that gave rise to all of Chinese medicine, it is stated that to be a master physician, one must master the use of metaphors as they apply to medicine and the body. Perhaps the best metaphor for the inner workings of the body as understood by Chinese medicine is that of a cooking pot suspended over a fire (Figure 5-1).
Mastering the simple implications of this analogy eliminates much of the confusion surrounding Chinese medical physiology and pathophysiology, and provides a solid foundation for understanding the use of herbs in Chinese medicine.
The best place to begin a discussion of the cooking pot analogy is with the fire underneath the pot. In Chinese medicine, this fire and the fuel that supplies it are the contributions of the Kidneys. Just as the fire is located underneath the pot, the Kidneys are located in the lower third, or jiao, of the body. In animals, this is equivalent to the caudal abdomen.
The “fuel” component of the Kidneys is Essence, or Jing. Essence is a sticky glutinous substance, tantamount to a sort of primordial ooze, which harbors the basic life force of the body. Tangible manifestations of this life-giving fluid stored in the Kidneys include semen, breast milk, and blood. It is not surprising then that Kidney failure was recognized early on in Chinese medicine as an important cause of anemia.
Essence is of two types—prenatal and postnatal—and is classified according to origin. Postnatal Essence is continually produced by the body through digestion. Foods that contain the raw materials that can be converted into Essence often are rich in animal protein. Cases of Kidney Essence deficiency, such as chronic renal failure in cats, are sometimes treated with the use of diets that are high in animal protein, calling into question the standard recommendation of most veterinary practitioners for low-phosphorus diets.
Prenatal Essence, which cannot be generated by the body, includes all hormones crucial to normal physical and sexual development, such as growth hormone, estrogen, testosterone, erythropoietin, and progesterone. Until the advent of synthetic versions by modern medicine, these hormones were irreplaceable once they were no longer produced by the body. Animals that lack prenatal Essence are thus prone to developmental abnormalities.
Although Essence has functions in the body in its own right, it can also be converted into just about anything else the body requires. In a sense, Essence was considered to function similarly to a stem cell in the bone marrow, with an inherent pleuripotentiality. Indeed, Chinese medicine recognized that the soft gelatinous material inside the cavities of bones was a major component of the body’s Essence pool.
Chinese medicine extended the definition of marrow to also include the soft gelatinous tissues of the central nervous system housed within the cavities of the cranium and the spinal column. The relationship of these tissues to Essence seemed obvious in that their function routinely declined as organisms slowly ran out of life-giving Essence and approached death. Declines in hearing, cognitive function, and memory are examples of symptoms of Kidney Essence deficiency.
Because marrow is a key component of both bone and Essence, bone integrity likewise came to be associated with Kidney Essence. Loss of bone strength that manifests as osteoporosis in humans and as lower limb and back weakness in many companion animals is an additional key symptom of Kidney Essence deficiency.
The ability of Essence to be converted into a number of different substances in the body makes it similar in concept to cash in a savings account. Similar to cash, Essence can be spent in a number of ways, but all expenditures can roughly be classified as having a Yin or a Yang nature. Yang is roughly equivalent to energy, and Essence may be mobilized to create Yang energy that can then warm or generally animate the body. Yin, or substance, may be produced from Essence to combat certain wasting conditions, or to keep the body moist during extremes of heat. Although it allows the organism to meet the temporarily high demands for Yin and Yang produced by disease or climate extremes, the penalty associated with Essence consumption is a potential shortening of the life span of the organism.
A third class of material produced by Essence is known as Qi (pronounced “chee”). Essence mobilization into Yin and Yang is the first step in this process, after which Yin and Yang interact to “ignite” each other. This process was envisioned to be somewhat similar to the powering of an oil lamp, wherein Yang energy is the spark, Yin is the oil, and the interaction of the two produces a flame known as Qi. Qi is the specific type of power consumed and stored by most of the internal organs. When an organ is lacking in power and is functioning poorly, it is thus often said to be Qi deficient. In the cooking pot metaphor for Chinese medical physiology, Qi is the flame that allows the cooking pot to function; the logs are the ultimate fuel source and represent Essence.
The Kidney’s main function in Chinese medicine is as a storage depot of Essence; in conventional medicine, a main function is the management of body water stores through alterations in urine concentration. In Chinese medicine, urine concentration is believed to be performed by the Bladder, which is thereby considered an absorptive organ. Specifically, the Bladder is believed to accumulate water absorbed from the digestive tract by the Small Intestine; it then sorts the water into pure and turbid components. Only pure substances and fluids are considered appropriate for storage within the internal organs of the body. Turbid materials are duly excreted. The Bladder’s function in storage and absorption is powered directly by the Kidney. Even in Chinese medicine, then, Kidney failure is considered the ultimate cause of a failure to concentrate urine, together with the common sequela of urinary incontinence.
Box 5-1 summarizes common symptoms of Kidney deficiency in small animals, as discussed earlier. Almost all symptoms are derived from a decline in body Essence, or Jing, over the life of the animal. It is not surprising, then, that these symptoms are also the most common signs of advancing age in both humans and animals.
The cooking pot hung over the fire of the Kidneys represents the digestive organs of Chinese medicine, particularly, the Spleen and the Stomach. The Spleen and the Stomach nourish the body by transforming raw materials in food into pure, useful substances such as Yang, Yin, Qi, Blood, and Essence. Apart from prenatal Essence, if a substance exists in the body, the Spleen and the Stomach are considered to have manufactured it. Their central location in the middle of the body matches this central role in manufacturing every one of its tissues.
The Stomach is the vessel in which the mechanical processes of digestion take place, including the secretion of digestive juices and peristalsis. When Stomach Qi does not promote peristaltic movement “downward” in an aboral direction but instead “rebels upward,” the result is emesis. Food may also simply linger in the Stomach, producing halitosis through the direct connection between the Stomach and the mouth.
The Spleen is considered to facilitate assimilation following digestion through the microvilli and the pancreas. Absorption of amino acids, glucose, and fats by mediated cell transporters within both the gastrointestinal lumen and even the body as a whole results from the presence of sufficient Spleen power, or Qi. If Spleen function is inadequate, the products of the Stomach’s efforts simply descend to be voided as watery, painless diarrhea, resulting in tissue atrophy and loss of weight. In Chinese medical parlance, then, the Spleen “raises the clear,” such that only the turbid, or impure, descends to the Small and Large Intestines.
Given its complete lack of any digestive function in conventional medical physiology, the labeling of the Spleen as a digestive organ is a source of discomfiture for many veterinarians who attempt to study Chinese medicine. The initial conjecture that the Spleen was a digestive organ was reasonable, however, given its obvious prominence in the human body in the exact location where digestion was quite literally felt to take place. The Spleen’s function was later determined as being filled by the pancreas; however, in humans, the pancreas is largely retroperitoneal and is almost indistinguishable from the adipose of the omentum, making it forgivable that the early Chinese did not identify it.
Once the error was made, it was difficult to undo. Because texts written even 1500 years ago are in daily use by Chinese medical practitioners, editing of all relevant Chinese medical literature would have been an onerous task, and it would have been unnecessary because Chinese medicine was not engaged in surgery or any physical manipulation of the organ itself. In the final analysis, it seemed less confusing and more harmless to simply acknowledge that, in light of present knowledge, a splenectomy could never cause digestive weakness, and that the practice of arbitrarily labeling the Spleen the organ of digestion can be continued for the purposes of discussion.
The products of digestion are numerous and include Blood, postnatal Essence, Yang, Yin, all fluids, and Qi. The stronger the function of the Spleen and the Stomach, the less often the organism must dip into its reservoir of Kidney Essence to meet the demands for these substances imposed by daily living. In the cooking pot diagram, we can see Essence dripping as a liquid fuel down to the woodpile and clouds of Qi wafting up to where these gather inside the lid of the cooking pot, or the Lung. Likewise, all other substances produced by the Spleen and the Stomach are stored only briefly before they are sent to the internal organ, where they are stored, or out into the circulation. The Liver is considered the main storage organ for Blood, and Ying Qi and Blood are the substances sent into the circulation. Ying Qi, which equates roughly to plasma, was correctly considered to carry the heavier or corpuscular elements of Blood. In keeping with the Spleen’s general role of uptake and assimilation, when the Spleen’s production of Ying Qi was deficient, Blood was not able to be held in the vessels, and it passively oozed out in a process known today as diapedesis.
The Spleen is the source of not only healthful fluids but pathologic ones as well. When the Spleen and the Stomach lack the power to adequately transform food and water into useful substances, the material that is produced instead is known as Dampness or Phlegm. Dampness and Phlegm behave as normal fluids do to some extent, going where normal fluids go, such as into the joints, the mouth, and the bloodstream; then, they simply accumulate as a useless detritus that provides the foundation for some of the most serious and common small animal disorders. Sometimes, the pathologic fluid accretes into masses; at other times, it simply serves as a source of friction with circulating energy, which it releases uselessly as heat. In the mouth, Dampness and Phlegm can be directly visualized as tenacious saliva or, especially in humans, as a thick, greasy coating on the tongue surface. Manufacture of Dampness and Phlegm is prevented when the fire under the cooking pot is adequate, and when the pot itself is not overfilled (Boxes 5-2 and 5-3).
|COMMON SIGNS OF SPLEEN DEFICIENCY||COMMON SIGNS OF STOMACH PATHOLOGY/DISEASE|
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