Key principles of Ayurveda: Dhatus (Tissues) and Srotas (Channels)
Updated: Jun 7, 2019
Ayurveda recognizes seven bodily tissues (Dhatus): rasa (plasma i.e. serum, white blood cells, lymphatic system), rakta (red blood cells), mamsa (muscle), medda (fat), asthi (bones and cartilage), majja (bone marrow, nerve tissue, connective tissue), shukra/artava (male/female reproductive organs).
The first and most important Dhatu is Rasa because this tissue feeds all the other six tissues in a chronological order. If the metabolism (Agni) of a Dhatu is impaired, this will affect the physiological function of the Dhatu and this will slowly affect the others Dhatus as well, but not necessarily in a sequence. The quality of the absorption (Agni) and assimilation of Rasa Dhatu impacts the quality of the rest in the chain.
There are over fourty types of Agni in the body, with 13 main types. The most important Agni is Jatharagni (discussed in detail in a previous blog post). In western terminology, thie is the hydrochloric acid in the stomach and enzymes in the small intestines. Glucose, water, saline and alcohol are absorbed through the stomach wall and transported directly to the hepatic portal system, while other carbohydrates, fats and proteins are further digested in the duodenum, jejunum, ileum by “Kloma Agni” (pancreas Agni) and eventually in the colon by Pakuashaya Agni. During this process, the digested nutrients are absorbed via the villi of the small intestine and transported to the liver where Bhuta Agni’s take over.
The Bhuta Agni’s (five Agni’s corresponding to the five elements), located in the liver, transform the five elements contained in the food into the five biologically available elements of the body that are then dispersed to the body’s tissues. The five Bhuta Agni’s have different functions: Nabhasa (ether Agni) sustains the shape of cells; Vayavya (air Agni) controls cellular respiration; Tejo (fire Agni) supports cellular metabolic activity; Apo (water Agni) sustains the cytoplasm, and Parthiva (earth Agni) manages mineral regulation.
The other seven of the main thirteen Agni’s are found in the seven tissues (Dhatus). The nutrients that are transformed by the Bhuta Agni’s in the liver are transported to feed, develop and tone the bodily tissues with the help of Dhatu Agni’s. The seven Dhatu Agni’s are responsible for the maturation and nourishment of each of the seven tissues.
The liver plays an important role in removing old red blood cells from the system. The liver governs the amount of blood in the body through the production of red blood cells i.e. erythrogenesis. The fire, water and earth Bhuta Agni’s play a crucial role in the production of red blood cells in the Rakta Dhatus. The liver secretes bile and excretes toxic waste like heavy metals and bacteria. It also maintains the acid-alkali balance in the body. Therefore, when the Agni’s related to the liver and spleen are functioning optimally, the immune system is functioning well and disease is less likely to occur.
OJAS AND IMMUNITY
In Ayurveda, the term Ojas describes a person’s vitality and immunity and it corresponds to the western medical definition of immunity. Ojas is the bodily substance that prevents aging, decay and disease; a person with strong Ojas rarely becomes sick. According to Dr. Vasant Lad,“it is a protoplasmic, biological substance that includes albumin, globulin, and many hormones. It is formed during the biosynthesis of bodily tissue, i.e. during the creation of the nourished Dhatus. In the same way, the end product of digested food plus agni creates the nutritional precursor called ahara rasa”.
As the Ojas of a dhatu supports Agni in the dhatu, when Ojas of a dhatu is depleted, its Dhatu Agni will be impaired leading to inadequate nourishment of the tissues. In Ayurveda, immunity depends upon the qualityof digestion (Agni), the quality of liver function (Bhuta Agni’s in the liver), and the integrated function of all hormones in the endocrine system. Chronic wasting diseases such as cancer are considered to a result of depleted of Ojas. If the innate immunity is sufficient then refined cellular nutrient extract (Ojas) would permit and support correct cellular function therefore cancer cannot persist. A genetic weakness of Ojas may be present in some families causing deterioration of tissues.
Srotas, meaning channels or pores, are present throughout the visible body as well as at the “invisible” or subtle level of the cells, molecules, atoms, and subatomic strata. It is through these channels that nutrients and other substances are transported in and out of our physiologies.
Srotas (channels) facilitate bilateral flow i.e. inflow and outflow. They are structures, which receive Dosha’s (biological humours), Dhatus (tissue nutrients and substances) and Mala (excretory products). Srotas transport dosha, dhatu and mala.
Sar is the extract from one tissue that is transported to the next. For examples, Rasa dhatu agni creates sara (nourishment), and mala (waste). Sara from Rasa dhatu is transported through Srotas to Rakta while the mala is excreted via other channels. Srota is responsible for building and maintaining the Dhatus (tissues), which are the building blocks of the body.
When the flow of appropriate nutrients and energies through these channels is unimpeded, there is health; when there is excess, deficiency, or blockage in these channels disease happens.
Most Srotas have obvious correlation to western concepts. Both Ayurveda and allopathic medicine recognise the Anna vaha srota (gastrointestinal tract) and the Prana vaha srota (respiratory channels). Other srotas have no exact western equivalent, for example the artava vaha srota carrying menstruation.
Ayurveda recognises thirteen Srotas:
Three Srotas connect the individual to the external environment, by bringing air, food, and water into and out of the body. Seven Srotas are associated with the seven bodily tissues (sapta dhatus). Another three srotas direct wastes out of the body.
However other ancient authorities recognize three additional srota relating to lactation, menstruation, and the flow of thoughts through the mind. This brings the total number of srotas to sixteen.
Here is a list of the sixteen srotas found in the human body:
Three Srotas link the individual to the external world:
Prana vaha srota are the channels carrying prana, the breath.
Udaka vaha srotas are the channels transporting water
Anna vaha srota are the channels transporting solid and liquid foods.
Seven srotas represent channels to and from the tissues (Dhatus):
Rasa vaha srotas are the channels moving plasma and lymph.
Rakta vaha srotas are the channels transporting blood cells and specifically hemoglobin.
Mamsa vaha srotas are the channels transporting muscle nutrients and wastes.
Meda vaha srotas are the channels supplying the various adipose tissues of the body.
Asthi vaha srotas are the channels that transport nutrients to the bones and wastes out of them.
Majja vaha srotas are the channels supplying the bone marrow and nerves including the brain.
Sukra vaha srota are the channels carrying the sperm and ova and supplying their nutrients.
Three srotas regulate the elimination of metabolic waste products:
Purisha vaha srotas are the channels that carry the feces.
Mutra vaha srotas are the channels that carry the urine.
Sveda vaha srotas are the channels that carry perspiration.
Two srotas are specific for women:
Artava vaha srotas, the channels that carry the menstruation.
Stanya vaha srotas, the channels carrying the breast milk during lactation.
One srota is associated with the mind (manas):
Mano vaha srota are the channels that carry thoughts, ideas, emotions, and impressions.
Disorders of a Dhatu are caused by the entry of a dosha into the Dhatu. This happens when a dosha becomes imbalanced or excessive and an over accumulation of the dosha occurs. The over accumulated or aggravated dosha will then leave its original residence in the body and move into the tissues where it causes quantitative or qualitative changes in the Dhatu.
Qualitative changes happen when the aggravated dosha enters the Dhatu, the qualities it carries affect the qualities of the Dhatu. For instance, if Vata Dosha enters rasa Dhatu, it carries the qualities of dry, light, and rough. This changes the inherent attributes of rasa Dhatu, which is oily, heavy, and smooth. Ideally, a person’s diet and lifestyle would support the attributes of Rasa Dhatu since it is the most important Dhatu, which feeds the rest of the six Dhatus.
Quantitative changes occur when there is an increase or decrease in the Dhatu. This happens when any dosha (Vata, Pitta, or Kapha) goes into a Dhatu and affects the nutrition of the Dhatu as well as the Agni (metabolism) of the Dhatu. When the Doshas cause slow Agni, there is excessive production of that Dhatu and when there is high Agni, there is reduced production of the Dhatu. In both of these conditions there can also be qualitative changes in the Dhatu. However qualitative changes can occur due to variable Agni without quantitative changes being present.
When these changes affect the immature Dhatu (tissues), they tend to be acute disorders. However, when any dosha goes into a mature Dhatu, it usually creates a chronic condition like for example Chronic Lymphocytic Leukaemia. It is interesting to note the similarities between Ayurveda and western science. In modern science the categorization of leukaemia as acute or chronic depends on the maturity level of the abnormal cells. The acute form results in an accumulation of immature cells while the chronic form allows more mature cells to be made in the bone marrow (Majja Dhatu) and blood (Rasa and Rakta Dhatu).
In Ayurveda, acute conditions can be treated simply as a Vata, Pitta, or Kapha imbalance, but when a chronic condition has persisted for years because the mature, fully formed dhatu (tissue) is affected, it becomes very difficult to treat. Both the excess dosha and affected dhatu need to be treated. Panchakarma is important in treating a chronic condition, as it eliminates excess Dosha’s, helps to reignite Dhatu Agni, and improves the quality of both immature Dhatu and mature Dhatu.
According to Ayurveda, the cause of the disease will imbalance Doshas, debilitate Dhatus and block the Srotas. The disease will only become noticeable when one or more Dhatus have developed weak immunity (caused by impaired Agni) and the channel (srota) leading to the Dhatu has become blocked. Excess Dosha’s settle only in tissues and channels of which the immunity has been weakened.
Together with knowledge of the Dosha imbalances, the Dhatus (tissues) involved, the state of the Agni (digestive fire), and other diagnostic means, assessment of the Srotas is one of the means in Ayurveda by which diseases can be distinguished. By knowing which Srotas are affected and the nature and extent of their disturbance, one can understand a great deal about the disease process.
“Disease is Nature’s way of forcing you to slow down and rest. This is why She is called Mother Nature: She loves you so much that She cannot bear to see you ruining yourself. She warns you of your errors over and over, and turns to drastic measures only when you obstinately refuse to listen to Her. It is a classic case of freedom versus responsibility: either you restrict your freedom a little bit each day, or Nature will come along and restrict it for you for days, weeks or months at a time.” Dr. Robert Svoboda. “Prakriti.”
Lad, V., (2002). Textbook of Ayurveda. Albuquerque, N.M.: Ayurvedic Press.
Pilmeijer, A., (2017). Cancer & Ayurveda as a Complementary Treatment. International Journal of Complementary & Alternative Medicine
The Gerson Institute for Ayurvedic Medicine