Dhatu are basically the body tissues which are responsible for the functioning of the systems and organs and the structure of the body. Each of the Dhatus is built out of a previous one and they develop on the nourishment that comes from the digestive system. They are basically the result of the action of catalysts that convert one tissue to another.

The sole purpose of metabolism is to assemble proper 'Dhatus' together in synchronization with which they carry out their role as the field of physiological activity.Dhatus which are of seven different types work in coordination with one another. They are: life sap (rasa), blood (rakta), muscles (mansa), fatty tissue (med), bones (asthi), bone marrow and nervous tissue (majja) and semen and reproductive system (shukra). It works in such a way that one tissue or dhatu transforms to the next from the nourishment they get from the digestive sysytem.There are seven dhatus in all rasa, rakta, mansa, med, asthi, majja and shukra.So from rasa (life sap) the body develops rakta (blood), from rakta it develops mansa (muscles), from mansa is developed med (fat), from med is developed asthi (bones), from asthi the body develops majja (nervous system) and from majja is generated shukra (semen).Thus according to ayurveda the seven dhatus are responsible for the immune system. The best thing about Ayurveda is that they follow a very specific method of treatment for diseases related to different dhatus.The growth and survival of the human body depends on these dhatus or the tissues. These seven dhatus are in turn made of five mahabhutas.When there is a slight disturbance or imbalance in the equilibrium of these dhatus it will result in ailments or diseases of the human body.

According to ayurveda rasa is the first dhatu which is the primary constitution of human body is otherwise known as sap or juice. It basically represents the fluids of the extra cellular and intracellular portions of the body and it mainly nourishes and strengthens the blood. Once the food gets digested it is converted into a liquid called as chyle or rasa which is further transformed into blood.

When the rasa dhatu gets refined then it is called as rakta dhatu which mainly nourishes the body by circulating to all cells and tissues of the body through the blood vessels.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. It also aids in gaseous exchange.

Mamsa is the muscle which makes up the internal organs of the body and is derived from the rasa and rakta dhatu.They constitutes the basic cover of bone and structure of body. These muscles are of different types and they are

• Hridya kandara: Cardiac muscle.
• Vartul kandara: Smooth muscle.
• Asti kandara: Skeletal muscle.

These are the adipose tissue commonly known as the fatty tissue. They are the refined part of the muscle dhatu which mainly helps in lubrication of the body organs. Apart from forming the basis of the adipose tissues the meda dhatu also constitutes the brain, spinal cord and nervous tissue. It also helps in maintaining right internal body temperature.

The Asthi dhatu are the main tissues responsible for the basic structure to the body. All the bones in human body are composed of a tissue termed as osseous tissue. All such tissue is termed as Asthi dhatu in Ayurveda. Asthi dhatu also include all cartilaginous structure in the body. They are the most solid form among all the other dhatus.

The Majja tissues are otherwise referred as myeloid tissue which is semisolid in nature and takes the colour of yellow or red. These tissues are supposed to be within the cavity of the bone and also said to be found inside the brain and spinal cord. It is the finer essence of the asthi dhatu.

This is the dhatu which is highly responsible for the reproductive elements of the body.It are the most refined product or essence of all the seven dhatus. It is referred by two different names wherein in male it is known as Sukra and includes the sperm and in female it is known as Sronita and is responsible for ovum.