So the odorants fit lock-and-key style into the receptors in our nose. Then what? do they fall out? get absorbed? Sit there forever, reducing our future capacity for smell?
Like most ligand/receptor interactions, the ligand usually eventually dissociates and dissolves away. There are many compounds that bind receptors irreversibly (many neurotoxins work this way for example), but I’m not aware of any specific examples in the olfactory system.
And hey, no mention of the G[sub]olf[/sub] cascade? Come on guys 
Rather than start another thread I’ll ask this here.
What is geosmium? I’ve done a dogpile search and a wikipedia search and I can’t find it.
Is it a variation on Osmium?
I think that’s supposed to be geosmin. It’s produced largely by soil microbes and has an archetypal earthy smell. Beets in particular owe a lot of their characteristic aroma to it.
I’m guessing your familiarity with it must be from chemistry.
Just from a long-standing interest in odorants and the aromachemical industry. I believe it is used fairly commonly both in earthy and “rainstorm” compositions, although the industry is deliberately cagey what specifically goes into its products (and I’m definitely not an insider).
[whoosh]I was referring to your screen name[/whoosh]
Oh – right.
Super whoosh.
The screen name is a misnomer. A screen misnomer, I guess.