Adrenaline, Cortisol, Norepinephrine.
The right ventricle will pump blood into the lungs to be oxygenated bia the pulmonary artery.
Smoking ruins your lungs making it harder to breath and get oxygen
you need oxygen when you exercise so you don't faint
smokers get less so it is harder for them, its like trying to exercise while breathing through a sponge or a straw os
