Specialized sensory neurons located in the olfactory epithelium within the nasal cavity. These cells are responsible for detecting odorant molecules in the air and transmitting signals to the brain, enabling the sense of smell (olfaction).
Specialized sensory neurons located in the olfactory epithelium within the nasal cavity. These cells are responsible for detecting odorant molecules in the air and transmitting signals to the brain, enabling the sense of smell (olfaction).
Olfactory receptor cells are bipolar neurons with a unique structure:
- Dendrites: Extend into the nasal cavity and end in olfactory cilia, where odorant receptors (a type of G-protein-coupled receptor) are embedded. These cilia increase the surface area for detecting odorants.
- Axons: Project through the cribriform plate of the ethmoid bone and synapse in the olfactory bulb, forming the first relay station in the olfactory pathway.
Each olfactory receptor cell expresses only one type of odorant receptor, and humans have around 400 functional receptor genes, allowing for the detection of a vast array of odors. When an odorant binds to its corresponding receptor, it triggers a signal transduction cascade involving cyclic AMP (cAMP), leading to depolarization of the cell and the generation of an action potential.
The axons of olfactory receptor cells converge onto specific glomeruli in the olfactory bulb, where signals are processed and refined before being transmitted to higher brain regions such as the olfactory cortex, amygdala, and hippocampus. This processing allows for the identification and perception of complex odor profiles.
Olfactory receptor cells have a high turnover rate, being replaced approximately every 30–60 days by differentiation from basal cells in the olfactory epithelium. This regenerative capacity is essential for maintaining olfactory function despite exposure to environmental toxins and pathogens.
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