system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why on earth can you smeel things by inhaling but not exhaling? Are my lungs odorless?
gpt
They aren't, but you've literally smelled them every waking moment of your entire life.  When the brain receives a constant stimulus, after a while it will start to ignore it, since it is no longer relevant information.