This document discusses breathing and prana (life force energy) in the human body. It describes how air moves through the bronchioles and alveoli in the lungs during breathing. The three processes of breathing are ventilation, oxygen-carbon dioxide exchange, and blood perfusion between the lungs and body. It then discusses the five main pranas or life forces in the body - prana, apana, samana, udana, and vyana - and their locations and functions in respiration, digestion, sensory functions and more. Pranayama techniques like kapalabhati, nadi shodhana and ujjayi breathing are introduced as ways to influence the pranas and