What happens to the respiratory system during exercise?

Normally resipartory system helps in carrying oxygen in carbon-di-oxide out.so,when you are sleeping or reading it functions normally.While during exercise the the Respiratory process takes place in a rapid moments...which increases oxygen intake twise as possible.The more the oxygen intake the more the blood gets purified and increses blood acceleration to main vital organs like heart,which inwards pumps more blood to brain,to work function and relatively it makes our active.