What binds hemoglobin instead of oxygen in smokers?

Answer 1

Nothing binds to hemoglobin instead of oxygen in the lungs in smokers. In the lungs oxygen is bound to hemoglobing for transport to organs and tissues while carbon-dioxide is release in the lungs for expiration.

You are probably thinking about the fact that smokers have lower oxygen uptake during inspiration than non-smokers.

1. Cigarettes fill your lungs with tare and makes them function at a lower quality than healthy lungs. It lowers the ammount of air you are able to inhale thus decreasing the ammount of oxygen.

2. Nicotine is a vasoconstrictor thus blood flow is impaired to your whole body. In the opposite reaction when you work out and need more energy to e.g. specific muscles, the body dilates those vessels leading there to get more oxygen to that area.