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The Gustatory System (Contains papillae: taste sensitive structures, three…
The Gustatory System
Contains papillae: taste sensitive structures, three types which are all mediated by a specific cranial nerve
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Each papillae may contain up to 100 taste buds, each of which contains 50-150 taste cells
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Taste cells are NOT neurons, they are polarized epithelial cells
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Basolateral surface: comes into contact with a neuron, creates taste afferents which send sensory information to the central nervous system via nerve cells
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Holds intracellular calcium stores that respond to depolarization of the receptor membrane or second messenger molecules - enters cytoplasm and triggers the release of transmitter molecules
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Salty
At low concentrations, salt-sensitive taste cells have a specially selective Na+ channel, which is blocked by amiloride when not activated by a gradient
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Bitter
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Bitter substances are detected by upwards of 30 T2R receptors - likely developed as an evolutionary protection against poison
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Sour
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Two possible mechanisms
Protons act by binding to and blocking special K+ selective channels in the taste cell - this will depolarize the cell
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Sweet
All sweet tastants, natural and artificial, are detected by the same possible GPCR's: T1R2 and T1R3 - both of these are required as a dimer for the detection of sweetness
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Gustation and taste info is sent throughout the brain, controls things such as vomiting (moderated by the hypothalamus) and connection of taste and memory (basal telencephalon)
Neural Coding of Taste
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Population coding: the responses of a large number of broadly tuned neurons specify the properties of a specific stimulus
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