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Homework Help: The nernst equation problem

  1. Jun 2, 2012 #1
    A rather tame ltxnsp was recently found on Easter Island by a retired neurophysiologist. He reported the following measurements of ECF and ICF concentrations (in millimoles):
    Pr+ 0 150
    Na+ ? ?
    K+ 10 100
    Cl- 109 250
    HCO3- 1 10

    so this is the question: He lacked the proper instruments for determining Na+ concentrations, but was rather certain that no other major ions were present in the ECF and ICF. Can you calculate either concentration for him?

    I think we use the Nernst eqn in this case to figure it out which is Em= 58/ z * log (xo/xi). correct me if i'm wrong. So Na and Cl is transported via the symporter so only charges are opposite. therefore we find the Em of Cl-? Then after that we find what's K? But then I don't get how to use those to tie it to find Na. I'm confusing myself here. Can someone help me out.
  2. jcsd
  3. Jun 2, 2012 #2


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    Science Advisor

    Try using net neutrality of the bulk.
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