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16 Cards in this Set
- Front
- Back
Taste buds consist of |
1. taste pore: opening through which fluids in mouth come into contact with surface of receptor cells 2. taste receptor cells: modified epithelial cells with microvilli |
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All tastes are varying combinations of what 5 primary tastes
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sweet, salty, bitter, sour, umami/savoury |
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Salty tastes are stimulated by |
chemical salts especially NaCl |
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Sour tastes are caused by |
acids which contain a free hydrogen ion, H+ |
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Sweet tastes are evoked by |
configuration of glucose |
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Bitter tastes are stimulates by |
more chemically diverse group of testants (alkoids, toxic plant derivatives, poisonous substances) |
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Process of gustation |
tongue/oral cavity -> taste buds -> taste receptors -> plasma membrane of taste receptors on microvilli -> binds w/ chemicals -> chem. binding alters ionic channels -> depolarization -> receptor cell synapses w/ afferent nerve fibres -> signals sent via synaptic input -> brainstem & thalamus -> hypothalamus and limbic sys (taste pleasant/unpleasant, behavioural responses) AND cortical gustatory (perception of taste & smell) |
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Process of salty taste |
stimulated by NaCl -> direct entry of Na+ activates Na+ ion channels on receptors pl. mem. -> causes depol. -> salty taste perception in brain |
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Process of sour taste
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citric acid in lemon -> yields acid & H+ ion -> H+ ion blocks K+ channels in receptors cell mem. -> results in decreases passive movement of K+ ions out of cell -> reduces internal negativity (more + charge inside) -> depol. (action pot) -> sour taste in brain |
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Perception of sweet taste |
glucose configuration -> glucose binds with taste cell receptor -> binding activates G-Protein -> turn on cAMP -> results in phosphorylation and blockage of K+ channels -> depol (action pot) -> sweet taste perceived in brain |
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Perception of bitter taste |
binds to receptor -> alters ion channels on receptors pl. mem. -> depol -> action pot -> different tastes |
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G-protein in taste |
Gustducin considered as one of the bitter signaling pathways (which sets off a 2nd msngr pathways in the taste cell) |
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Perception of Savoury (umami) taste |
AA glutamate in meat, glutamate binds to G-Protien -> activates a 2nd msngr pathways -> depol -> action pot -> perception of savoury taste |
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cAMP is |
a second messenger pathway in taste cell |
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By 4th month baby prefers __________ to __________ and taste begins to by influenced by experience |
prefers salt water over plain water |
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What happens to taste buds with aging?
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there is a decline in the number of taste buds - sweet taste remains by sour, salty and bitter decline |