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the primary olfactory epithelium is located at the top of the nasal cavity
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odourants are dissolved in the mucus layer and are bound to olfactory binding proteins that chaperone the passage of the odourants to the cilia-like projections of the olfactory receptor neurons (ORNs)
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unlike other special sense receptors, the olfactory receptor membrane is found on the primary afferent neurons (i.e., receptor=primary afferent)
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olfactory receptor cells are the only neurons that are regularly replaced throughout life (via differentiation of supporting basal cells)
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ORN axons enter the CNS through the cribriform plate to synapse in the olfactory bulb
- the olfactory pathway is the only sensory pathway that does not relay in the thalamus
- axons from mitral cells in the olfactory bulb form the olfactory tract
- these axons synapse in various cortical regions (anterior olfactory nucleus, piriform cortex, the medial amygdala and entorhinal cortex)
- these direct connections to the limbic system explain why odours are usually the most powerful sensory stimuli for evoking memories
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