Roughly 80% of what we call the flavour of food is really smell, which is why a blocked nose makes a meal taste like nothing even though the tongue still registers all five tastes. Odorants have to dissolve in mucus, bind the olfactory cilia and report to the bulb; a combinatorial code lets some 400 receptor types tell apart on the order of a trillion odours. In olfactory adaptation the signal starts strong then fades although the smell persists; in anosmia the molecules still bind while no neuron fires.
Roughly 80% of what we call the flavour of food is really smell, which is why a blocked nose makes a meal taste like nothing even though the tongue still registers all five tastes. Odorants have to dissolve in mucus, bind the olfactory cilia and report to the bulb; a combinatorial code lets some 400 receptor types tell apart on the order of a trillion odours. In olfactory adaptation the signal starts strong then fades although the smell persists; in anosmia the molecules still bind while no neuron fires.
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