Faizan Kalwar

Basal cells – replace receptor neurons (a feature unique to the olfactory neurons)

Sustenacular cells – scattered throughout epithelium, secretory granules empty contents on mucosal surface

Receptor neurons

- Humans have ~40 million- Bipolar neurons- Dendrites extend into

mucosal surface-Cilia on surface of

dendritic knobs-Receptors on cilia make

contact with odorants-One receptor for each

neuron- Axons lead into glomerus

-Odor molecule binds to receptor protein on surface of cilia

-Receptor conformation changes activates G-protein (Golf)

-Adenylate cyclase activation produces cAMP

-cAMP opens ion channels Na+ and Ca2+ enter

- Depolarization occurs at dendritic region which leads to generation of an action potential

-Activation of multiple receptors allows molecules that have never been encountered to be characterized

-ORNs are sensitive to a subset of odorants which makeup its tuning curve

- Some ORNs are very selective while others are much broader

-Different thresholds exist for a given odorant between neurons with the same receptor

- Adaptations occur