system
Given the following post, respond as if you're commenting on Reddit:
human
How do our lungs separate the oxygen from all the other elements in the air?
gpt
They don't. Whatever you breathe in will end up in your lungs. In your red blood cells, hemoglobin has a high affinity for oxygen, so preferentially binds it. If you are breathing a gas that has a higher affinity for hemoglobin than oxygen (like carbon monoxide), then that molecule will preferentially bind instead of oxygen.