There are a million things that can be said about the wonderful process of breath…
On the physical level, every time we inhale, oxygen is being taken into the body from the atmosphere towards the lungs, and through the blood it is diffused to the cells where the “internal respiration” takes place. In parallel, carbon dioxide is being released from the cells with each exhale, and is being carried through the blood back to the lungs from where it is expelled by “external respiration”.