Ayurveda classifies the human body into seven constituents, or Sapthadhathu. These are the elements in the human body that nourish, grow and support the body and mind. The seven dhatus are:
Rasa Dhatu: Plasma/lymph fluid
Rakta Dhatu: Blood
Mamsa Dhatu: Muscles
Meda Dhatu: Fat
Asthi Dhatu: Bone
Majja Dhatu: Bone marrow
Shukra Dhatu: Reproductive fluid or Semen
Rasa Dhatu (plasma): This dhatu is a transporter of the body-plasma fluids and provides nourishment to all the other dhatus. The Rasa dhatu is supported by the kapha dosha
Rakta Dhatu (blood): This dhatu is the basis of life and provides nourishment to all the tissues and cells in the body. It also provides strength to the body and color to blood. The Rakta dhatu is supported by the pitha dosha
Mamsa Dhatu (muscle): This dhatu provides movement to the muscular system in the body. It provides physical support to the meda dhatu. The Mamsa dhatu is supported by the kapha dosha
Meda Dhatu (fat): This dhatu collects the energies and stores it to provide strength to the body. The adipose tissue also stores fat as a means of body lubrication and a support to bones. The Medha dhatu is supported by the kapha dosha
Asthi Dhatu (bone): This dhatu includes all the bones and cartilages and gives shape to the body. It also supports the Mamsa dhatu. The Asthi dhatu is supported by the vata dosha
Majja Dhatu (bone marrow): This dhatu refers to bone marrow. It nourishes the body and helps maintain its functions. Majja dhatu strengthens the body, fills the bones and nourishes the Shukra dhatu. The Majja dhatu is supported by the kapha dosha
Shukra Dhatu (reproductive tissue): This dhatu nourishes the reproductive strengths of an individual. It includes sperm and ovum. The Shukra dhatu is supported by the kapha dosha.
All the seven dhatus are inter-connected; the malfunctioning of a single dhatu can have an impact on all the other dhatus. The dhatus are composed of the five mahabhutas or elements. Thus, the doshas, which are also made up of the five elements help manage the balance of the dhatus. A system of well-balanced doshas helps balance the dhatus, thus leading to the proper functioning of the entire system of the body.