The seven dhatus are:
Rasa- literally, “ sap” or “juice.” Rasa represents tissue fluids, including chyle, lymph and blood plasma. Its accessory tissues are breast milk and menstrual blood and its waste products is mucus. Its function is prinana ( nourishment).
Blood ( Rakta) - red blood cells. Its accessory tissues are blood vessels and tendons and its waste is bile. Its function is jivana (invigoration).
Flesh (Mamsa) - skeletal muscle, its accessory tissues are ligaments and skin and its waste are those which accumulate in body orifices: ears wax, snot, navel lint, smegma, and so on. Its function is lepana ( “plastering” of the skeleton).
Fat ( Medas) - fat in the limbs and torso. Its accessories tissue is omentum and its waste is sweat. Snebana ( lubrication ) is its function.
Bone (Asthi) - all bones. Its accessories are the teeth and its waste body hair. Beard and nails. It provides the body with dharana (support).
Marrow ( Majja)– anything inside a bone, including red and yellow bone marrow as well as the brain and spinal cord, which are wholly encased in bone. Its accessory tissue is head hair and lachrymal secretions are its waste. It performs putana ( “filling” of the bones).
Shukra & Artarva - male and female sexual fluids. Shukra’s tasks are garbbotpatti (reproduction) and the production of Ojas, the fluid that generates the aura and controls immunity. It has neither accessory tissues nor waste products.
The Doshas are present inside the dhatus (tissues). When they undergo abnormalities, they give rise abnormalities in the tissues supporting them. Both these abnormalities together give rise to diseases which start within the dhatu/ tissue involved.
The first dhatu the rasa-satisfies the other tissues by supplying them nourishment; the second dhatu, rakta- supports life by producing heat, making the heart work etc., the third dhatu, mamsa, covers the bony frame and gives contour to the body; the fourth, the medas provides lubrication, by its greasy nature; the fifth, the asthi supports the body by its hard frame, the sixth the majja, fills the cavity of the bones and the seventh dhatu, the sukra, of the male and its counter-part, artava (from the female) help the formation of the foetus. These are only the important functions and there are many other functions also for each dhatu.
Just as food is essential for the growth of the body, even so, for the growth of the tissues food is necessary. 'The preceding dhatu (tissue) produces the food for the succeeding dhatu.
As long as the dhatus are healthy and well formed, and the wastes are minimal and quickly excreted, ahamkara experiences maximal satisfaction in her incarnation and the individual experiences a deep somatic sense of well-being. When there is inadequate dhatu nutrition ahamkara feels this lack, and her dissatisfaction is transmitted to the consciousness of the individual in question. Digestion and assimilation are essential to an individual’s well-being at all levels.
Ayurveda states that each dhatu is formed from the one immediately previous to it, except the accessory tissues, which are only nourished and do not nourish in return. Breast milk and endometrium, for example, are meant for nourishing a child and play no further part in the mother's nutrition. The wastes produced at each stage of dhatu digestion are used in diagnosis, since excess of any waste is indicative of poor digestion at the level of that dhatu.