Ayurvedic concepts regarding what the human body is composed of are derived largely from the teachings of Sage Kapila and the Sankhya school of philosophy founded by him. According to the Sankhya school, the dualities of Prakriti [matter] and Purusha [pure self or consciousness] lie at the centre of the Universe, and the Pancha Bhutas [Five Great Elements] or Maha Bhutas evolved from them.
The three main components of the body - dosha, dhatu and mala - are formed from these Maha Bhutas. Doshas are the chemical energies responsible for bodily functions, and their imbalance causes diseases. Dhatus are the tissues, and Malas are the materials excreted from the body. Each of these three components is further subdivided based on the functions performed by them.
As per Ayurvedic philosophy, our health is decided by the equilibrium of these energies. Properly identified, these forces can be harnessed to maintain health, treat ailments and rejuvenate our bodies.