Inhale, exhale, it's natural! We breathe without even paying attention... Yet, our whole body is in motion!
First, oxygen enters through our nose, where it's filtered by tiny little hairs. Then, the air travels down the trachea, into the bronchi, bronchioles, and finally the alveoli... What a journey! These alveoli pass the oxygen into the blood... And off it goes, through the pipes! Well... into the arteries.
Once the cells have used up the oxygen, they release carbon dioxide... Turnaround! This gas follows the same path but in reverse!
And who ensures blood circulation? The heart, of course! Tireless, it never stops... The atria receive the blood, the ventricles send it out... and all in rhythm!