OLFACTION: TRANSDUCTION SEQUENCE

1. Odorant dissolves in mucus film of the olfactory epithelium and diffuses to olfactory cilia of receptor cell; solubility aided by odorant binding protein (OBP)

2. Odorant molecule bind to specific receptor, causing P_Na and/or P_Ca to increase by G-protein coupled second messenger mechanism (cAMP, IP₃)

3. Na⁺ influx &/or Ca influx lead to depolarization to threshold and generation of an action potential, which travels on the receptor cell axon through the cribiform plate of the ethmoid bone to the olfactory bulb, where the axon synapses with mitral cells and tufted cells