The various vital air passing through these canals mix with each other. The heat which lives in Prana is called Ushman. This heat causes digestion in embodied creatures.
प्राणानां संनिपाताच्च संनिपातः प्रजायते। उष्मा चाग्निरिति ज्ञेयो योऽनं पचति देहिनाम्॥