Hare Krishna,

Dandavat Pranam.

The vital force of a living entity includes the five kinds of air working within the body, which are known as prana, apana, vyana, samana and udana. The vital force is compared to a serpent because a serpent can live by simply drinking air. The vital force carried by the air is described as the pratihara, or the bodyguard. Without the vital force one cannot live for a moment. Indeed, all the senses are working under the protection of the vital force. 

I heard the Life air is the interface between gross and subtle body.

What is vital force?

What is life Air, prana, apana, vyana, samana and udana ?

What are their functions ?

What is their relation with soul ?

Hari Bol !!!