The word Dhatu means ‘support’, in Sanskrit. Tissues form the infrastructure of the body. “Dhatu” also means ‘metal’. Metal is a substance, which are solid (exception, Mercury in liquid form) and give strength. There are seven types of such Dhatus (structural elements) that constitute human body.
These Sapta (seven) Dhatus (tissues) elements are the pillars of the body that form the means of nourishment and growth while providing support to the body as well as the mind. Dhatus are structural blocks of the body. They constitute the body -termed as S’areera. The most important difference between theDoshas and the Dhatus is that the latter perform functions under the influence of the Doshas.
During the process of metabolism, the Dhatus supporting the body, undergo twofold conversion into excretion and essence, having been acted upon by the respective one of the seven Agnis.
Rasa (fluid) Dhatu – It represents the primary constitution of the human body. It is the extract of food we eat. Rasa Dhatu-the first of the seven structural elements refers to both extra cellular and intracellular portions of fluid in the body. Derived from the digested food, it nourishes each and every tissue and cell of the body and is analogous to the plasma.
Rakt (blood) Dhatu – The word Rakt refers to Blood. Thus, Rakt Dhaturepresents the blood derived from the digested food; it nourishes each and every tissue and cell of the body and is analogous to the plasma. Regarded as the basic of life, it is analogous to the circulating blood cells. It not only nourishes the body tissues, but also provides physical strength and color to the body.
Mans Dhatu (muscles) – The muscle tissue, which constitutes many internal organs as well as the muscles, its main function is to provide physical strength and support for the med (fat) Dhatu.
Med (fat) Dhatu – Consists of adipose tissue providing support to Ashti Dhatu. Commonly, adipose tissue comprises of all deposits of fat-distributed in the body. It also lubricates the body.
Ashti Dhatu – All the bones in the human body are composed of a tissue termed as osseous tissue. Such tissue is termed as Ashti Dhatu in Ayurved. Comprising of bone tissues, including cartilages, its main function is to give support to theMajja Dhatu and provides support to the mans (flesh) Dhatu.
Majja Dhatu – Majja is bone marrow. Denoting the yellow and red bone marrow tissue, its main function is to fill up the Ashti and to oleate the body.
Shukar (sperm): Shukar represents the reproductive elements. This includes the sperm in males and ovum in females. Apart from these elements, Shukar also refers to cellular reproductive elements. The main aim of this reproductive tissue is to help reproduction and strengthen the body.
Formation of dhatus:
During the process of metabolism, the dhatus supporting the body undergo twofold conversion into excretion and essence having been acted upon by the respective one of the seven Agnis.
The formation of dhatus takes place in the following order-Rasa, Rakt, Mans, Medas, Asthi, Majja and Shukar. Shukar respectively from its pure essence produces foetus.
Food also nourishes the upadhatus (sub dhatus) in the following manner-Rasa nourishes breast-milk as well as menstrual blood in women. Rakt (blood) nourishes tendons and blood vessels, mans (muscles) nourishes vasa (oily) as well as six layers of skin and medas (fat) nourishes the ligaments and joints.
The Excretion of food is faeces and urine. Rasa excretion is Kapha (mucus, phlegm, spit), that of Rakt (blood) is Pitta (bile), Medas (fat) excretion is sweat, that of Asthi (bones) is nails and hair in head and body that of Majja (marrow) is fat in joints. Thus the fractions of essence and excretion formed during the process of metabolism support each other and thus maintain the body by mutual coordination.
The specific potency of the intake of aphrodisiacs etc. exhorts its effect quickly. Some take this process of conversion completed in a period of six days. The gradual conversion of dhatus runs incessantly in a cyclic order.
Rasa, the essence of food, acquire redness from the color of the fire-like Pitta. The same acted upon by vayu, water, and fire and cooked further attains solidity and thus converts into flesh. It is further cooked by its own heat and being predominated by its own heat, water and the unctuous properties is converted into Medas (fat). Further the innate heat combining Prithvi (earth), fire, vayu etc. together gives rise to hardness and thus produces Asthi (bones). Within the bones vayu creates hollowness, which is filled up by the marrow, the essence of Medas (fat). From the essence of marrow, semen is produced. By vayu, Akash (space) etc. porous ness is produced in bones through which semen comes out like water from the new earthen jar. Semen moves through its carrying vessels in the whole body and propelled with force from sexual ecstasy and passionate determination gets displaced and liquefied like ghee. Then by physical exertion comes out of the urinary passage like water flowing towards the lower surface.
All dhatus nourish each other and thus produce Rasa, Rakt sperm etc. respectively. But the Vrishya (sperm productive herbs), Vajikarna (aphrodisiac treatment) directly get converted into vrishya (semen). It is their natural properties. Some say it requires six days for conversion of one Dhatu to another. And so on the process of conversion of one Dhatu to another goes on.
Rasa (including Rakt) is always, everywhere, continuously and simultaneously thrown (into circulation) in the body by the vyana vayu (air) performing the function of throwing. Rasa while in circulation sticks somewhere due to morbidity in channel, causes disorder there, like a cloud in the sky causing rain. Doshas also get aggravated in localized parts in the same way.