Being one of the panchamahabhoota, agni (fire) has the characteristic that it cannot exist without a base. For example, coal, kerosene etc. are few substances in which agni exists. Like wise in the body it exists in pitta dosha. Agni is responsible for the following functions :-

» Digestion - indigestion (Pakti- Apakti)
» Vision- absence of vision (Darshaman- Adarshaman)
» Degree of heat (Matra- Amatratvamushmanala)
» Normal -abnormal complexion (Prakriti- Vikariti varman)
» Prowess- fear (Shauryan- Bhayan)
» Anger exholoration (krodham- Harsham)
» Confusion- clarity (Mohan- Prasadan)
» Apart from the above mentioned dual traits reflected by all human beings there are many other dual nature traits that occur in the body and agni is responsible for it.

Classification
Agni present inside the body is classified in thirteen types, namely :-
1. Jaathragni
Present in the pachak pitta, tis main function is of digestion and to strengthen other types of agni present in the body in its prukratic (natural) state.

2. Sapta Dhatwagni
The agni of each and every dhatu in its own srotas is responsible for their metabolic changes. These are :-

» Rasa Dhatu Agni
» Rakta Dhatu Agni
» Mansa Dhatu Agni
» Meda Dhatu Agni
» Asthi Dahtu Agni
» Majja Dhatu Agni
» Shukra Dhatu Agni

3. Pancha Mahabhootaagni
As the name denotes these are five in numbers, one for each mahabhoota. It is responsible for the transformation of asharir mahabhoota to sharir mahabhoota.

In ayurveda it is believed that everything is made up of five elements and so is the body. These five elements are the panchmahabhoota and are responsible for constituting every living being in the world. Agni transforms the Asharir Mahabhoota (external mahabhoot) to Sharir Mahabhoota. Example - When we drink water Jala Mahabhoota (water) dominates and later the water is transformed by Jala Mahabhoota agni to the Sharir Jala. Five Mahabhoota Agni are as follows :-

» Akasha Mahabhoota Agni
» Vayoo Mahabhoota Agni
» Agni Mahabhoota Agni
» Jala Mahabhoota Agni
» Prithvi Mahabhoota Agni

Besides performing all the metabolic functions agni takes care of digestion (ahar pachan) and in the absence of ahar it acts on the ama pachan i.e. properly metabolize the improper metabolites. When ahar and ama are absence Agni does the function of dhatu i.e. rasa, rakta etc. Digestion of dhatu is a fatal condition in which dhatus are broken down to get energy. The reduction or deficiency of the quantum of dhatu in the human body leads to the disease called Kshaya roga.

In ayurveda it is believed that all the pathology occurs due to the impairment in Agni (Kaya). Hence the correction of Kaya i.e. Agni is called the treatment or Kaya Chikitsa in ayurveda.

According to ayurveda all the pathology occurs due to the impairment in agni ( Kaya). Hence the correction of Kaya i.e. Agni is called as treatment or Kaya Chikitsa in ayurveda.