In Ayurveda, Dhatus are said to be the fundamental base of the body. Dhatus support the basic structure and functions of the body. Dhatus are of seven in number viz. rasa, rakta, mamsa, medas, asthi, majja and shukra. These are the structures that make up the body. However, like most concepts in vedic literature, they are much more than their one-dimensional definitions, they are integral to understanding the relationships of the tissues in the body and they are sites that doshas enter when they cause disease. An understanding of the seven dhatus is important to understanding pathology or, what goes wrong in the body.
Rasa literally means ‘sap’ or ‘juice’. The primary function of ‘Rasa’ is to strengthen ‘rakta’ (blood) and provide nourishment. Basically, the tissue fluids consist of lymph and blood plasma. Accessory tissues are the breast milk and the menstrual blood. The rasa dhatu, being made up of the element water, has similar qualities. It is cold, heavy, moist, soft, stable, smooth, flowing, cloudy, gross and dull. These qualities are very similar to kapha dosha, which is made up of water and earth. Thus, the health of rasa dhatu plays an important role in determining the health of kapha dosha.
Physical satisfaction is the sense of health and well-being that every cell experiences when it is well nourished. Psychological satisfaction is the feeling that our most basic needs have been met. As a result, there is a solid foundation for healthy psychological growth. When rasa dhatu is depleted, the qualities of kapha and water diminish. The skin becomes dry and rough, dryness in the bowels produces constipation and dry mucous membranes lose their ability to resist disease becoming fertile ground for infections. In addition, the secretion of breast milk is diminished in nursing mothers and menstrual flow becomes scanty.
Rakta Dhatu is said to be constituted from the metabolic refinement of the Rasa Dhatu. The primary function of the Rakta Dhatu is the nourishment of the body. It is also said to be the preserver of life. The rakta dhatu, being made up primarily of the element fire, has similar qualities. It is hot, light, dry, hard, unstable, rough, flowing, clear, subtle and sharp. These qualities are very similar to pitta dosha which is made up of mostly fire and a little water. Thus, the health of rakta dhatu plays an important role in determining the health of pitta dosha.
Rakta Dhatu is the carrier of the fire that invigorates the body and mind. As such, when rakta dhatu is healthy, a person feels energized with a healthy passion for life. When rakta dhatu is depleted, the qualities of pitta dosha and fire diminish. A person feels cold, the skin loses its luster becoming pale or dusty gray, and coldness causes the body to hold on to heat by becoming constipated and by reducing urination and sweat. When the rakta dhatu is in excess, the qualities of pitta dosha and fire increase. A person feels warmer. As heat builds up in the body, it tries to evoparate through body. Thus, redness of the eyes, skin etc. can be seen. Bowel movement, urination frequency etc. can be seen increased.
It is formed from the rasa and rakta dhatu and said to be the basic cover of bone and structure of body. Mamsa dhatu, made up of earth and fire, has the following qualities: hot, heavy, dry, hard, unstable, rough, dense, cloudy, gross and sharp. These qualities are similar to a combination of pitta and kapha doshas and, as such, these doshas play the greatest role in its development and health.
Meda Dhatu are the finer part of the mansa dhatu that are also known as fatty tissue. They keep the lubrication between the various body organs and help the body in maintaining right internal temperature.
Meda dhatu is built primarily from the water element and secondarily from earth. The presence of water reveals the nourishing nature of fatty tissue. The presence of earth reveals its role in stabilizing the functions of the body and mind. Meda dhatu has a counterproductive relationship with the remaining elements. As it fills the empty space of ether it reduces inspiration. In excess, this results in a closed mind. It also acts as an obstacle to air slowing down the movements of the body. In excess, it creates lethargy. And it suppresses fire reducing metabolic activity. In excess, digestion becomes sluggish and all dhatus begin to increase. However, for these same reasons it is protective against conditions of excess ether, air and fire.
Asthi i.e bones are the finer essence of the Meda Dhatu, which are converted into the most solid form of the Dhatus. They give the basic structure to the body. Asthi Dhatu is mainly associated with Vata dosha and then Kapha dosha. The Mahaabhootaas associated with Asthi dhatu are Earth and Air. Excessive Asthi Dhatu results into abnormal growth of bones and teeth, very dense hairs, and calcification. Whereas, deficiency of Asthi Dhatu results into conditions like osteoporosis, hair falling, and cracked or debilitated nails.
Majja (Bone marrow)
Majja is the finer essence of the Asthi Dhatu. It is basically a semi- solid substance, yellow and red in color. Its primary function is filling the bone. It is also found inside the brain and spinal cord. The skull is the casing of the brain. The vertebra are the casing of the spinal cord. While the brain and spinal cord make up the central nervous system, the Majja dhatu is associated with the entire nervous system. The nervous system and the bone marrow are treated as homologous structures in Ayurveda.
In order to produce majja dhatu the primary elements that must be taken in the proper balance are air and water. The balance of air regulates the flow of nerve impulses. Water provides a counter balance to air, protecting the nerve against excessive motion and agitation. The brain as well the myelin that surrounds the structure of the nerve consists largely of fat. It is composed primarily of the element water and has kapha-like characteristics.
Shukra (Reproductive fluid or Semen)
Sukra is produced from the most refined essence of the Bone Marrow. It is the cause of Ojas, which is actually the essence of all the seven Dhatus. The Shukra is responsible for vitality and energy of the body. In Ayurveda, the term is commonly used to describe both the male semen and the female egg, as they contain the essence of all of the other dhatus (tissues) of the body. Shukra is the seventh and final dhatu in the dhatus formation cycle. At times, two distinct terms are used to describe the male and female seed. Shukra universally applies to sperm but can also apply to the entire makeup of semen. Artava is the equivalent term used to mean ovum. However, artava also refers to the menstrual blood, a product of rasa dhatu. Thus, shukra is the best term to describe the factor that nourishes both the male and female reproductive tissues. In order to produce shukra dhatu, the primary element that must be consumed is water. Water is the primary nourishment of the body and of the dhatus, and shukra is its most refined form.