Each dhatu is a metabolic refinement of the previous dhatu. As such the action of the ranjaka pitta on the finest essence of the rasa dhatu forms the rakta dhatu (blood). The characteristic red coloration of the blood is due to the presence of this pitta in the rakta dhatu. The chief functions of this dhatu, whose dominant element is agni (fire), are the nourishment of the body and preservation of life. Like rasa dhatu, rakta, dhatu too circulates all over the body. The persons having best quality of Rakta have the qualities of happiness, sharp intellect, magnanimity, tenderness, moderate strength, lack of endurance, and intolerance to heat.