14 -- Chemical Senses

14 -- Chemical Senses - Chemical Senses Chemical Senses...

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Chemical Senses
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Chemical Senses Taste Smell Both mediated by specialized CHEMORECEPTORS CHEMORECEPTORS found in various regions of the body – other chemoreceptors besides taste and smell: Carotid artery O 2 and CO 2 in blood Hypothalamus O 2 and CO 2 in CSF as well as other dissolved substances C-polymodal chemonociceptors Work together to provide full appreciation of “flavor”
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Taste Despite seemingly endless possible “flavors”, likely that body responds to 5 basic tastes: Sweet Salty Bitter Sour Umami Substances we eat contain various combinations of these basic tastes “flavor” of food comes from combination of tastes and smells associated with it texture and temperature also give important clues to identity and flavoring of food
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Taste Anatomy Tissues of the tongue, palate, pharynx, etc. have important role in tasting Focus on tongue: contains 3 types of PAPILLAE PAPILLAE Each papilla has variable # of TASTE TASTE BUDS BUDS A taste bud contains ~100 TASTE CELLS TASTE CELLS that transduce chemical stimuli into neural signal
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TASTE Taste cells of a bud have apical and basal ends APICAL END APICAL END - has microvilli - arranged around pore BASAL END BASAL END - makes synapse with sensory neuron that will carry signal into CNS Basal cells Basal cells replenish supply of taste cells (act as stem cell population)
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Taste Transduction of tastants microvilli of taste cells contain a variety of molecular components (taste receptor molecules) Each of the 5 basic tastes uses a different mechanism of transduction A single taste cell may contain the necessary machinery to transduce more than one of the basic tastes
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Taste Transduction of “SALTY” Salt-sensing cells have specialized sodium channel Always open Bind to a drug called amiloride When salt-containing food interacts with tongue, increased sodium conc. drives Na + ions into taste cell through channel Inward current of positive ions depolarizes cell Activates voltage-gated Na + and Ca 2+ channels Calcium triggers NT release Neurotransmitter used uncertain, maybe serotonin or ATP APICAL APICAL BASAL BASAL
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This note was uploaded on 03/23/2009 for the course BIOL 450 taught by Professor Jeremyingraham during the Spring '09 term at UNC.

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14 -- Chemical Senses - Chemical Senses Chemical Senses...

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