2007 Sensory Physiology

Olfactory epithelia

  • the olfactory epithelium is located at the top of the nasal cavity
  • unlike the receptors of the other special senses, the olfactory receptor membrane is found on the primary afferent neurons (i.e., receptor=primary afferent)
  • olfactory receptor cells are the only neurons that are regularly replaced throughout life (via development of basal cells)
  • axons of olfactory receptor neurons (ORNs) enter the CNS through the cribriform plate to synapse in the olfactory bulb
  • odourants are dissolved in the mucus layer and are bound to olfactory binding proteins

Nasal cavity

Olfactory receptor cells

(Relatively) New discoveries

  • mammals have 2 types of olfactory epithelia:  MAIN OLFACTORY EPITHELIUM (MOE) and VOMERONASAL ORGAN (VNO)

  • and 3 types of receptor neuron:

    • in MOE:  OLFACTORY RECEPTOR NEURONS (ORNs) and GC-D NEURONS

    • in VNO:  VOMERONASAL NEURONS
  • different types of olfactory receptor neuron utilize different transduction proteins and central pathways

Olfactory epithelia

Zufall and Monger 2001

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