Sapta means seven and dhatu means that which bears or supports. Ayurveda identifies seven vital tissues that provide nourishment, growth, and structure to the entire body. These tissues are called dhatus which are in many ways similar to the major tissues identified by modern science.

The Sapta(seven) Dhatus (tissues) elements form the pillars of the body that form the means of nourishment and growth while providing support to the body as well as the mind.

Rasa (fluid)Dhatu – This dhatu is a transporter of the body-plasma fluids and provides nourishment to all the other dhatus and is analogous to the plasma.Its made up of water element.Rasa means to move.The Rasa dhatu is supported by the kapha dosha.

When rasa dhatu is depleted skin becomes dry, and hard, person is dull, lean, tired, and intolerant to loud speech and noise.
When rasa dhatu is in excess loss of appetite, excessive salivation, nausea laziness, feeling of heaviness, coldness, cough and excess of sleep is felt.

Functions:
It makes the person cheerful, happy and leaves the skin glowing and nourishes Rakta dhatu

Rakta (blood) Dhatu – It can be compared with formed elements of blood like Red Blood Cells(RBC), White Blood Cells(WBC), and Platelets etc.Its made up of fire element.

Functions:
It takes care of our complexion, nourishes Mamsa dhatu and is governed by pitta dosha. 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 .In the mind, depletion of the rakta dhatu leads to dullness, and difficulty processing and understanding new information. This often leads to confusion and misunderstandings.
When the rakta dhatu is in excess, the qualities of pitta dosha and fire increase. A person feels warmer.

Mamsa Dhatu – The muscle tissue, its main function is to provide physical strength and support for the meda dhatu.Its made up of earth element.

Functions:
Strengthens the body, builds good muscle tissue in neck shoulder and thigh area. Nourishes meda dhatu and is governed by kapha dosha and earth element. When mamsa dhatu is depleted then it causes debility of sense organs, emaciation of cheeks, buttocks, pain in joints.
When mamsa dhatu is in excess then produces enlargement of lymph glands, tumors, increase in size of cheeks, thighs, abdomen etc.
Meda (fat)Dhatu – 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.

Functions:
Well lubricates system, with oily and soft hair, skin and efficient eyes. Nourishes Asthi dhatu and is governed by Kapha.
When medas dhatu is depleted then it leads to spleen enlargement, difficult joint movements, emaciation at abdomen, desire to consume fatty food. When medas dhatu is in excess then person gets tired, fat increases at abdomen, thighs, neck etc, and foul smell in sweat, shortness of breath etc.
Asthi Dhatu – 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.Its made up of air and space elements.

Functions:
Supports the body. Gives good structure and stability with hard working capacity to the body. Nourishes Majja dhatu. Asthi dhatu is governed by vata dosha.
When asthi dhatu is depleted then there is pricking pain in bones, falling of teeth, nail and hairs.Bones become porous, get easily fractured.
Increase in asthi dhatu lead to excessive growth of bones. Bones and teeth are developed over one another.

Majja Dhatu– 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

Functions:
Imparts sharp, clear mind with good intellect and memory. Strong joints.Govern by kapha dosha. When majja dhatu is depleted then bones get weak, joint pain, vertigo, giddiness occur and shukra dhatu is also depleted. When majja dhatu is in excess then heaviness in eyes, and whole body occurs.

Shukra Dhatu – This dhatu nourishes the reproductive strengths of an individual. It includes sperm and ovum. The Shukra dhatu is supported by the
kapha dosha.

Functions:
Has patience, enjoys life and body strength. Reproductive needs are concern. Govern by kapha dosha. In case of shukra dhatu depletion ejaculation is delayed, bloody ejaculation occurs, pain in testicles, body is weak and thirst occurs. When there is excess of shukra dhatu desire of excess coitus is there and stone in the shukravaha strotas may occur with pain.

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.

Ojas is the ultimate “essence” of each dhatu. The most effective way to improve the health of the dhatus is to increase ojas.

Improper diet and digestion, on the other hand, will lead to ama formation in each tissue layer.