Saltiness receptors function via _______________.
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   the simple influx of sodium ions (or other cations from metallic salts) across the membrane causing depolizaration.; | 
   
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   the opening of calcium ion channels in the presence of hydrogen ions; | 
   
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   the activation of a G protein; | 
   
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   the blocking of potassium efflux; | 
   
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   none of the alternatives provided are correct; | 
   
   
   
   
   
   [Review Part 1 of the tutorial]
   [Review Part 2 (Matching) of the tutorial]