system
Given the following post, respond as if you're commenting on Reddit:
human
When I inhale a scent, do I also exhale that scent?
gpt
"Scents" are aromatic molecules that pass by your olfactory receptors, binding to them, and sending a chemical message to your brain. Not everything binds, however, and may pass into the alveoli of your lungs. Then, when you exhale, the molecules are expelled. So in a sense, you are exhaling the smell. More specifically, you are exhaling the aromatic molecules that bind to olfactory receptors, and they return to the external atmosphere.