Yoga is an energy management system. The Prana Vayus are the 5 ways prana (life force energy) is split in the body and utilized to maintain physiological function.
Prana - energy flow in head and chest
Samana - spiral energy of digestion in and around the solar plexus/navel
Vyana - energy flow governing circulation and distribution
Udana - upward flowing energy governing communication
Apana - downward flowing energy governing elimination
Point to Point breathing meant to balance Prana in the 5 vayus. Lay down on your back in savasana. Get comfortable!