Why do we breathe?
Simply put, we breathe to exchange gases. Oxygen – specifically molecular oxygen, O2 – is key to the production of adenosine triphosphate (ATP) in cells, the energy-carrying molecule responsible for delivering chemical energy to fuel everything from cell division to nervous system signalling to muscle contraction. ATP is the reason you can grow muscles, command chains of kinetic movement and, ultimately, power a bicycle.
However, ATP production creates a byproduct – carbon dioxide, or CO2 – which must be expunged, since while CO2 is not toxic to humans per se, it is an asphyxiant, meaning it leaves no room for oxygen molecules. Breathing, and hence our respiratory system, is the key to getting oxygen in and carbon dioxide out.
How does breathing work?
Oxygen enters the…
