Modern medicine is based on physics, Chemistry, Botany, and Zoology. Ayurveda is based on Indian Philosophy - the theory of macrocosm and microcosm. Man is the epitome of greater universe. Matter is composed of five elements (Panchamahabhuta). They are Prithvi (earth or hardness), AP (water or liquid), Teja (fire or energy), Vayu (gaseous state of matter) and Akasha (ethereal state of matter). The existence of any matter is attributable to Kala (time) Dik (space). Manas (mind) and Atma (soul) are essential to make it animate. These nine components are called the Nitya dravyas or eternal elements. Just as the universe has the sun, moon and wind, in the same manner all living beings have motion, liquid and the heat or energy component. They are called Vata, Kapha and Pitta respectively. Living body is composed of Panchamahabhuta i.e., the five basic elements like universe and they are explained in terms of Dosha, Dhatu, and Mala. Life is the union of body, sense organs, mind and soul. The dosha are vata, pitta, kapha. The seven Dhatus are Rasa (chyle or nutrient fluid), Rakta (blood), Mansa (muscle tissue), Medas (fats), Asthi (bone, connective tissue), Majja (bone marrow) and Shukra (reproductive elements or the vital substance). The three main Malas or excretions are purisha (faeces), mutra (urine) and sweda (sweat). The doshas when exist in dynamic equilibrium help to maintain the human body in a healthy condition. Then they are called Dhatus. Any disturbance in this equilibrium causes malfunction and results in disease. In that event they are called Doshas. Thus Vata, Pitta, Kapha, are alternatively called Dhatu or Dosha depending on the effect they have on the functioning of the body.
Vata: The root "Va" is derived from va-gatigandhnayah i.e., which has motion. Vata initiates and promotes biological activity responsible for all the movements of the body.
Pitta: Responsible for generation of heat and all actions relating with digestion, absorption, metabolism, pigmentation of skin, vision, intelligence and ego.
Kapha or Sleshma: Responsible for moistening of ingested food, nutrition to the heart, mind and body tissues, perception of taste and lubrication of joints.
Vata,Pitta and Kapha are further classified into five types depending on their situation and normal physiological conditions.
Just as the body is governed by the three doshas, the mind is also governed by three attributes - Guna, mental Doshas. They are called Satva, Rajas and Tamas. Satva is responsible for righteous and kind thoughts and feelings. Rajas is for arrogance, desire, love and passion. Tamas is for sleep, stupor and ignorance.
Food, behavior and thoughts will increase, decrease or neutralize the physical and mental Doshas.