BASICS OF AYURVEDIC PHYSIOLOGY
The basics of Ayurvedic medicine (traditional Indian medicine) are set down in a few ancient texts, of which the Charaka Samhita is the principal resource. As described by Dr. P. Kutumbiah (1), "The Charaka Samhita stands as the finest document of the creative period of ancient Indian medicine (600 B.C.-200 A.D.), in regard to the extent of its contents and to the state of its preservation....Charaka is the most rewarding author among the writers of classic medicine..." This voluminous book corresponds, both in its historical time of origin and in its implications for the future practice of traditional Indian medicine, to the Huangdi Neijing and the Shang Han Lun of Chinese traditional medicine. The contents of the Charaka Samhita have been explained and expanded upon in the Ayurvedic body of literature in much the same way that the well-known Chinese texts have been analyzed and broadened in China. The information for this article is derived from my understanding and interpretation of that provided in several of the secondary sources, which are sometimes contradictory or utilize markedly different explanations.
For those who are interested in Tibetan medicine, that system is based largely on the Ayurvedic system, with translation of terms into the Tibetan language and the addition of some Tibetan Buddhist concepts, along with some local remedies (2). Because I expect most of my readers to be somewhat familiar with Chinese medicine, I have, in some cases, made comparisons to that system in the following presentation. In recent years, others have made the effort to compare and contrast these two great traditions (3). No attempt has been made in this article to be comprehensive in the description of Ayurvedic physiology; it is hoped and expected that those who find this subject of interest will consult suitable texts for further details.
In several respects, humans are miniature versions of the universe to which they belong. The universe is comprised of the five great elements (panchamahabhutas): the ether (or the space-time in which forms can exist), fire, water, air, and earth. In the human, there are these five elements, but also four animating forces: the soul (atma), the mind (mana), the cyclic life processes, including rebirth and death (kala), and the senses (indriyas). The animation of the five elements to produce the human has a correlation to the vast universal animation and consciousness. According to Svoboda (3), "Nature, as manifested through individual bundles of ego, has three attributes (gunas): sattva (equilibrium), rajas (activity), and tamas (inertia)....Sattva evolves into the thinking mind, the five senses of perception, and the five senses of action....Tamas evolves into the objects of the cognitive senses-sound, touch, form, taste, and odor-which in turn produce the five great elements....Rajas is the force which brings the senses and their objects together." The gunas also manifest in the human as behavioral and moralistic tendencies.
Like the Chinese system, Ayurvedic medicine places strong emphasis on groupings of five (see: To call wuxing five elements or five phases?) to depict many features of nature and of humans. However, in place of the two-fold system of yin and yang in the Chinese understanding of the universe, the Ayurvedic understanding is based on a three-fold system. Aside from the three gunas described above, the principal point of integration of the human with the universe and universal consciousness is the three doshas (to be described in detail below).
The meaning and nature of three doshas (tridosha) is complex to grasp. A variety of translations for doshas have arisen, including powers, influences, faults, humors, and transporters. The complexity of the underlying concepts defy easy translation into one-word definitions. In part, this is because the doshas take on a different appearance and meaning depending upon what aspect of human life one is investigating.
The tridosha concept has been linked to a fundamental Buddhist concept, called the three poisons (4). According to this view, the human being exists because the undifferentiated and untroubled universal spirit is influenced, as it flows through the manifest world, by the three disrupting forces: attraction (desire), aversion (hatred), and confusion (conception and misconception), yielding the "ego bundles." In producing the human body and mind, attraction gives rise to the sense that "I" am a human being, rather than any other kind of being. Aversion gives rise to the sense that "I" am imperfect and mortal. Confusion gives rise to the sense that "I" am separate from everyone and everything else. As a result of these three influences, the pure, all-encompassing, peaceful, universal consciousness becomes a mortal, lonely human being.
It is the ultimate task of a human-a task that takes many lifetimes in the ongoing cycle of life, death, and rebirth-to relinquish these influences (poisons) and attain the goal of pure undifferentiated consciousness (nirvana). Unfortunately, the three influences are quite powerful, especially confusion (i.e., the separation of self from others); therefore, the human life is marked by continual struggle, and the experience of suffering.
The human body exists as a physical entity because of the mixing of the five elements and four animating forces; kaya, the cyclic process, includes the karmic linkage that draws one to a birth following death. The three poisons-which affect the animating forces directly-yield the three doshas, which, in turn, affect the five elements. As Robert Svoboda (3) has described it, the doshas "bind the Five Great Elements down into living flesh." From this view, the doshas are properly called the three faults.
Although not visible, the doshas are never absent from the human being, rather, they are an integral part of the body and its condition of health or disease; in this sense, they are, as C.S. Kundley has said (5), "powers controlling human life." One of their normal roles in the body is to produce the internal movements; in that sense they may be called transporters. But movement does not occur without substance: there is something that moves. The moving substances within the body are usually termed humors. These humors help to nourish the structural components of the body (dhatus), including muscles, joints, blood, and bones (to be described in detail later in this article). The doshas control the humors, but their relationship to the humors is so close that it is not uncommon for the doshas to be directly identified with the humors by some authors. The three doshas are labeled kapha, pitta, and vata.
Kapha corresponds to confusion, it is the transporter of fluids, and is the controller of the phlegm humor. Its function is associated with building up of body tissues and stored substances. It is also associated with cooling or restraining, including keeping the mind calm. To a certain extent, kapha has a quality similar to yin in Chinese physiology.
Pitta corresponds to aversion, it is the transporter for substances involved in metabolism and transformation (it may be identified with the metabolic activities themselves), and controls the fire or bile humor. Its function is associated with the digestive processes, keeping the body warm, and driving mental and physical activity. To a certain extent, pitta has a quality similar to yang in Chinese physiology.
Vata corresponds to desire, it is the transporter of air and energy, and is described as the controller of the wind humor. Its function is associated with breaking down body tissues and eliminating stored substances, and it has a "roaming" nature. To a certain extent, vata has a quality similar to internal wind in Chinese physiology, except that vata has a cold nature, while the internal wind of Chinese medicine is usually associated with warmth (deficient liver blood, a yin, cooling substance, permits the agitation of liver yang, including liver fire and internal wind). Vata may also be compared to the Chinese concept of qi, at least to the extent that it is always moving, that it permeates the whole body, and is the fundamental motive force in breathing, the heart pump, and skeletal muscles; as with internal wind, qi is associated with warmth, while vata is associated with coldness. The unique aspects of vata, compared to the standard Chinese concepts, makes it quite difficult to directly correlate the two systems of physiology, disease etiology, and treatment. In Tibetan medicine, vata is perhaps the most important concern, as its imbalances relate to mental agitation, which is contrary to the Buddhist goal of equanimity of mind.
In a person who is physically healthy, the three doshas are present in appropriate "amounts," their quality is pure, and their "transporting" activities are calm and orderly. In a person who is unhealthy, at least one, but almost always two or three of the doshas are relatively deficient or excessive, their quality has become impure, and their transporting activities disorderly. These latter two aspects, impurity and disruption, are commonly called "vitiation" (the affected doshas are "vitiated"). In this sense, one can again view the doshas as "faults"-in the sense of things that can go wrong. A term for imbalance of the doshas is tundoskopa: anger of the doshas.
Each of the doshas has a location in the body where it generates the corresponding humors and from which it takes its actions (as transporters). These sites are also where vitiation is most likely to occur. Kapha has its seat in the stomach, pitta in the small intestine, and vata in the large intestine. That is, the three doshas have their initial and dominant influence in what we call the gastro-intestinal system.
From this understanding, one can easily appreciate the importance attributed to food consumption by Ayurvedic doctors. Food (and beverage) enters the gastro-intestinal system and portions of it encounter, one by one, the seats of the three doshas. Interacting with the doshas, the food is transformed and transported and made into the substance and movement of the body.
Rules as to the time of eating, the amount to be consumed, the ratio of food to water and the ratio of those to the amount that could potentially fill the stomach, the quality of the foods (including their tastes, lightness or heaviness, and texture), their method of preparation, and their combination with spices and other "herbal" materials, are all deemed of great import in relation to how the body forms and functions. Dietary adjustments are the most important aspect of healing, at least for the long-term.
We can recognize today that the three poisons-attraction, aversion, and confusion-affect our pursuit of diet and continue to make it a primary health concern. People are attracted to eating too much food and foods that are not suitable for their needs; they have an aversion to foods (and herbs) that are healthful but which don't have the tastes or textures of the attractive foods, and an aversion to spending the time necessary to properly prepare the foods; they are confused about what to eat and which messages to give attention to. (Should it be hunger sensation, desire for taste or texture, advertising claims, the conflicting claims of various health-promoting philosophies...?) It is not uncommon for the appetite to be disorderly, the stomach to be rebellious, the small intestine to be inflamed, irritable, or unsuccessful at digesting and assimilating the food, and the large intestine to be blocked, rumbling, or in spasms.
Certainly, dietary considerations are not the only ones that affect the body. However, because of the principal sites of the three doshas in the gastro-intestinal tract, diet and the condition of the gastro-intestinal system are frequent contributors to disease and healing.
Following are some of the expected manifestations of deficiency, excess, and aggravation (vitiation) of the individual doshas:
Kapha deficiency: sensation of dryness or internal burning, feeling of emptiness in the stomach and other cavities of the body, looseness of the joints, thirst, weakness, and insomnia.
Kapha excess: whiteness of complexion, heaviness of limbs, feeling of coldness, drowsiness, excessive sleep, and looseness of the joints.
Kapha vitiation: aversion to food, inertness of limbs, vomiting, and impaired digestion.
Pitta deficiency: dullness of complexion and reduced body heat
Pitta excess: burning sensation of the body, desire for coolness, yellowish coloration (of skin, eyes, feces, urine), insufficient sleep, fainting fits, weakness of sense organs.
Pitta vitiation: heat (fever or hot sensation)
Vata deficiency: languor, uneasiness, loss of consciousness.
Vata excess: roughness of the voice, thinness of the body, dark complexion, desire for heat, throbbing sensation, hard stool, insomnia, and weakness.
Vata vitiation: swelling or distention of the abdomen, rumbling sound of the intestines.
Some individuals have a natural tendency towards excess or vitiation of a dosha, and this is deemed to be a "constitutional" condition. The constitution (prakruti) that affects an adult may have been present at birth and/or the result of long-term dietary and behavioral patterns. For example (6), it has been said that persons who have the imbalance of dominant inherent vata may be born with crooked bodies that are thin and bluish in complexion; their joints produce a cracking sound during movement, and these individuals are easily susceptible to the adverse effects of cold breezes; they tend to be boisterous (fond of singing, laughing, arguing, and fighting). Those who are born with dominant pitta will tend to feel hunger and thirst at frequent intervals, the color of their skin and hair will be yellowish, they will be of medium height and weight, and will be intelligent and proud. Those who are born with dominant kapha will tend to become fat and have pale complexions; they may live long and have comfortable lives (becoming rich, being jolly and helpful by nature). Of course, there are several possible permutations of two or more inherent doshic influences. Repeated behaviors and experiences can contribute to developing constitutional imbalances: going without sleep, experiencing a lot of suffering, and staying in windy places can lead to a vata dominance; drinking alcohol, getting into fights, and staying in overly hot places can lead to pitta dominance; over-eating and staying in damp and cold places can lead to a kapha dominance. Each lifestyle imbalance or indiscretion, especially when extreme or repeated frequently, can affect one or more of the doshas.
In the particular situation, one might be deemed, by an Ayurvedic practitioner, to have a kapha, pitta, or vata constitution (or a combination of any two). Such constitutional analysis is considered an important aspect of Ayurvedic medicine (7). Individuals with inborn or long-term constitutional imbalances might be counseled to follow a particular set of dietary instructions and behavior modifications to counteract the tendencies towards ill health that result from the lack of balance in the doshas. In addition, there is, in the Ayurvedic system, a description of psychological and moral constitutions based on the three gunas. According to Vasant Lad (8), those with satvic mental constitution are religious, loving, compassionate, pure minded, have good manners, behavior, and conduct; they do not get easily upset or angry. Those with rajasic constitution are egotistic, ambitious, aggressive, proud, competitive, and have a tendency to control others; they work hard but lack proper planning and direction. Those with tamasic constitution are less intelligent, tend toward depression, laziness, and excess sleep; a little mental work tires them easily and they are greedy, possessive, attached, and irritable. As with the doshas, there can be various combinations of these attributes, depending on the relative predominance of the gunas. One should be careful, however, to not oversimplify either the understanding (diagnosis) of a disease condition nor its path to resolution (treatment) by relying on a constitutional analysis alone, as is often presented in popular books about Ayurvedic health care principles.
Aside from constitutional factors and diet, the doshas are affected by environmental changes. The most consistent environmental influence is the changing of the seasons. Ayurvedic doctors (like Chinese doctors) caution everyone to be attentive to the seasonal changes and to adjust their habits accordingly. This means adjusting the sleep schedule, the diet, the clothing, and the types of daily activities, so that one can counteract the adverse aspects of the seasonal influences (in the Chinese system, the six qi) and gain the benefits (e.g., harnessing creative energy) from harmony with this natural dynamic.
Further, the doshas can be affected by how we use our senses and what general activities we pursue. If our mind is adversely affected by what is heard, seen, or felt, a disease or disorder might arise; its treatment might involve carefully regulating what is permitted in the sensory field. If we work too much, excessively participate in sexual activity, or undertake other physically stressful activities, or if we inappropriately resist involvement in natural activities, then it is also possible for a disease or disorder to arise.
In the Ayurvedic literature, a series of steps has been outlined through which diseases develop as a result of accumulation of the doshas (1). It is always possible for a disease to bypass one or more steps, but it is common for illnesses to develop roughly in accordance with this pattern.
This type of disease progression might occur, for example, from constant overeating or from weakness of the digestive functions, or both. If one considers the case of chronic sinus infections and congestion (see: An epidemic of sinus disorders), this is a disease that manifests (in the fourth stage) as minor congestion. Then, as it enters the fifth stage, there is a chronic disease: perhaps repeated or chronic congestion with frequent infections. At the sixth stage surgery is often performed, because, if it is not, the person is unable to carry out usual daily activities and there is the threat of systemic infection that could lead to death. In the Chinese system, a description of disease stages, such as the six stages of disease caused by cold influence and the four stages of disease caused by heat influence, is considered an important aspect of understanding not only the progression but also the treatment of diseases.
The localization of a disease depends upon several factors: which doshas are affected will have some influence, as well as the characteristics of the dosha-disturbing nidanas. Additionally, the interaction of the doshas with the body structures (dhatus), with the ducts (srotas; the narrowed passages through which the doshas must flow), and with the waste products (malas) yield the particular disease manifestation. For example, various urinary disorders may arise when the kapha dosha accumulates and is excited (vitiated). This kapha infiltrates the fat (dhatu), as well as the urine (mala), and it obstructs the urinary ducts (srotas). The excretion of those contaminants that have built-up in the fat then accumulate in the kidney (where their outflow is blocked by the congested ducts) and are affected by the kapha, which has the qualities of being cold, hard, slimy, oily, heavy, and condensed. The result may be build-up of stones, mucoid discharge, and/or easy susceptibility to urinary tract infection. Not uncommonly, the build-up of thick substance causes pain, usually in the lower back, in the bladder, and/or in the urethra.
It is recognized by modern Ayurvedic doctors that microorganisms and viruses can cause disease. These agents disrupt the doshas, and they are understood to be different than the seasonal, dietary, and other traditionally-recognized causes of disease. Of course, if their already exists an imbalance of the doshas, it will make a person more susceptible to the harmful influence of microorganisms and viruses.
The structural components of the body are called dhatus. There are seven types of dhatus (saptadhatu), and it is understood that each one is nourished, in turn, from another, until the processes of refinement and transformation of essences derived from food produce the life-sustaining ojas that pervade the entire body.
Each refinement process yields a pure substance and a waste product (mala). The mala is something that is to be excreted. The refinement of food yields ahara-rasa, the pure essence, and it yields the malas of feces and urine. The refinement of ahara-rasa yields the rasa dhatu, an activated nutritive essence (corresponding, roughly, to the Chinese concept of yingqi). Blood (rakta) is obtained from refinement of the rasa dhatu; the mala of the rasa dhatu is mucus. The blood is then refined to form flesh (mamsa), and the mala of the blood is bile. The flesh is refined to form fat (medas), and the mala from this forms the excretions from the eyes, nose, and ears. The refinement of fat yields the bones (ashthi), and the mala is sweat. The refinement of the bones yields marrow (majja), and the mala is hair and nails. The refinement of marrow yields semen (sukra; corresponding roughly to the Chinese concept of jing), and the mala is the oil of the skin. The refinement of semen yields the ojas; this process generates no mala. The rasa and ojas, the first and last refinements, nourish the entire body and all the dhatus.
The dhatus serve the role in Ayurvedic medicine that the zangfu serve in Chinese medicine. For each of the zang, there is an associated structural component and body substance (e.g., spleen-muscle-moisture; kidney-bone-essence; liver-tendons-blood) and there is an associated fu that handles materials that are to be excreted (corresponding to the mala). Although the roles of dhatu and zangfu are similar, the way in which they are visualized and associated with natural phenomena differ considerably, so that one cannot draw too many parallels.
Changes in the malas, such as their quality, quantity, or (as sometimes applies) frequency of discharge, are important signs of the type of illness being experienced. Ayurvedic doctors pay particular attention to the malas of feces, urine, and sweat. In the Tibetan medical system, urine evaluation has evolved as a central diagnostic criteria. The overall quality of a person's complexion, presence, spirit, and resistance to disease are signs of the condition of the ojas, the end refinement of the body substances. Since the ojas come from refinement of sukra (described as semen, but also present in females), traditional Ayurvedic specialists, like their Chinese counterparts (notably the Daoists), are concerned about loss of semen, and therefore recommend specific restraint techniques associated with sexual activity. However, the most important means of benefiting the ojas is maintaining the health and balances of doshas and dhatus and ingesting a nutritious and balanced diet.
The different tissues of the body interact with one another via srotas, which are sometimes described as being "ducts" but basically represent areas where blockage can occur. There are 14 srotas (two of them in females only) affecting the physical structures: those involving the respiratory system, the digestive system (upper portion), the water system (intake and distribution), the lymphatic system, circulatory system, muscular system, adipose system, skeletal system, nervous system, reproductive system, sebaceous system, excretory system (intestines), urinary system, menstrual system, and lactation system. Each srota may be affected by a deficient flow of substances (in which case, the system to be nourished is weak), an excess flow of substances (in which case the system being nourished usually shows agitation or one will observe excessive drainage), a blockage of flow (often creating a mass), or a bypass (overflow) which usually manifests with substances appearing where they should not normally appear. In addition, the mind is considered to have a srota (mandvaha srota) that effects the flow of emotions, sensory impressions, and thoughts in a manner parallel to that of the physical srotas.
In some ways, the srotas are like the Chinese meridians (jing), in that the types of disorders that can occur (deficiency, excess, blockage, overflow) are similar in nature and the concept of forming connections is similar. While the Indian system has a separate depiction of flow pathways (nadis), the early conception of the Chinese meridians, which was as blood vessels, seems closely allied with the broader Indian conception of srotas, seen as narrow passageways through which substances flow.
There are many more concepts in Ayurvedic medicine not mentioned here, but the five elements, four animators, three gunas, three doshas, seven dhatus, three principal malas (there are six basic types of malas), and the twelve (for males) or fourteen (for females) srotas largely describe the basic functioning of the body. The doshas are the agents of flow, change, and influence; the gunas affect behavior, attitude, and morals, the dhatus are the structural components and the holders and releasers of the nourishing materials and wastes (malas); and the srotas are the passageways through which substances flow. Disorders may occur from or result in the doshas being excessive, deficient, or agitated (vitiated); the dhatus being insufficiently nourished, over-nourished, or structurally damaged (and they may hold too tightly, or release too easily, the substances that enter); the malas being excessive, deficient, or polluted (and their elimination abnormal in terms of frequency and timing of discharge); and the srotas may pass too little or too much substance, or they may become obstructed or bypassed. These various problems, and others, involving the mind, soul, gunas, etc., arise from a combination of spiritual influences, dietary factors, and environmental influences (including disease-causing agents and injurious physical impacts). By analyzing the disturbances, the Ayurvedic physician can recommend corrective action in terms of diet and behavior, and can apply various remedies, such as oil massage and ingested herbal compounds. Ultimately, resolution of spiritual problems will yield the true health that is sought by all.
Acknowledgment: Communications with Robert Svoboda, Kim McCarthy, and CS Kundley were especially helpful in this attempt to describe the complex Ayurvedic medical field; the author takes full responsibility for any errors or misconceptions in the final presentation.