Healthy olfactory neurons have numerous olfactory receptors coupled to G proteins.

Upon binding an odor molecule, they activate adenylate cyclase III (ACIII), which generates cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP).

cAMP activates cAMP-gated calcium channels (CNG), leading to calcium influx, which in turn triggers an action potential.

Calcium influx also shuts the cAMP signal down by triggering phosphodiesterase (PDE) activity, leading to cAMP degradation to adenosine monophosphate (AMP).