Study author Johannes Reisert, PhD, a Monell Center cell physiologist, comments, "Ion channels and how their currents change ion concentrations inside cells are notoriously difficult to study. Our modeling-based approach enables us to better understand not only how olfaction works, but also the function of small nerve endings such as dendrites, where pathology is associated with many neurodegenerative diseases."
In the study, published online in advance of print in the Proceedings of the National Academy of Sciences, the scientists asked why olfactory receptor cells communicate with the brain using a fundamentally different series of electrical events than used by sensory cells in the visual or auditory systems.
Olfaction - Process - Fitting - Lock - Chemical
Olfaction begins when, in a process similar to a key fitting into a lock, an airborne chemical molecule travels through the nasal mucus to bind with an olfactory receptor embedded on the wall of a nerve cell within the nose. The olfactory receptors are located on cilia, elongated super-thin threadlike structures less than 0.000004 inches in diameter, which extend from the nerve cell into the mucus.
The act of odorant-receptor binding initiates a complex molecular cascade inside the olfactory cell, known as transduction, which results in the nerve sending an electrical signal to inform the brain that an odor has been detected.
Transduction - Process - Opening - Pores - Ion
The transduction process culminates with the opening of pores called ion channels, located in the nerve cell's wall. The open pores enable positive or negative electrically charged molecules (ions) to flow in and out of the cell. This ultimately changes the cell's overall electrical charge to a less negative state, which is what initiates the cell's signal to the brain.
Most ion channels are selective for a specific ion, including positively charged sodium (Na+) ions or negatively charged chloride (Cl-). The flow of an ion through its channel in either direction generates an electric current.
Receptor - Cells
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