The five प्राणस् (life breaths) of any living being are प्राण , अपान , व्यान , समान and उदान . There is a story in 'Devī भागवत ' regarding the origin of the पञ्चप्राणस् .

Once श्री कृष्ण met राधादेवी at रासमण्डल and in seclusion they spent in sexual sport the period of one day of ब्रह्मा . Then कृष्ण selecting an auspicious time dropped his vital fluid into her womb at the end of the sexual sport. Tired by the prolonged carnal sport and shaken by the impact of the hot semen राधादेवी perspired profusely and the exhaustion produced deep and long breaths. The whole universe was covered with her sweat and her sighs became the goddess of the life-giving breaths of all created animals. From the left side of goddess was born वायुपत्नी and to her were born the पञ्चप्राणस् . Besides these, another five younger प्राणस् were also born. From the sweat of the देवी was born वरुण and from the left side of वरुण was born वरुणानी . (9th Skandha, Devī Bhāgavata) .

माण्डूक्योपनिसद् gives the following details regarding the working of the प्राणस् in the body:-- प्राण was first used in the sense of breath. Later it got the meaning of life. Life is in fact breath to all living beings. Only when a man is awake, his mind and sense organs are active. But प्राण is active always both in the state of wakefulness and sleep. Therefore प्राण is the vigour of life. It may be said that when a man is asleep his senses merge with his mind and his mind with the प्राण . The five factors of प्राण are the पञ्चप्राणस् . The first of the five is called प्राण itself. It is called मुख्यप्राण or chief प्राण . Just as a King appoints his ministers at different places to do specified jobs the chief प्राण posts the other प्राणस् at different parts in the body with specific purposes of their own. प्राण is seated in the heart and does the work of breathing. अपान is seated in anus and directs the organs of excretion of the body. व्यान is spread throughout the body and it is this life-wind which keeps one alive even when breathing is stopped for some time. When an archer stands in deep concentration with his bent bow without breathing he lives with the help of व्यान . समान controls the breathing-in and breathing-out to a specified rhythm. समान (equaliser) is so called because it balances the force of the in-coming and outgoing breaths. There is a school of thought that प्राण is not seated in the heart but spread over the ears, eyes nose and face. समान is seated at the navel midway between the seats of प्राण and अपान . This is also a reason why life wind got that name. This breath does the work of prompting digestion. The four प्राणस् , प्राण, अपान, समान and व्यान sustain life. The fifth one, उदान , takes the soul of the being out of the body when it dies.