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Chapter 4 The Action Potential. Nernst Relation. [ion] out [ion] in. E = 61.54 mV log 10. Goldman Equation. P k [K o ] + P Na [Na o ] P k [K in ] + P Na [Na in ]. V m = 60 log 10. Time Course of Action Potential. Injecting Current into Neuron.
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Nernst Relation [ion] out [ion] in E = 61.54 mV log10
Goldman Equation Pk[Ko] + PNa[Nao] Pk[Kin] + PNa[Nain] Vm = 60 log10
Question 1 • A new monovalent ion, zirconium, is found to be 100 times more concentrated outside than inside the neural membrane. The neuron has channels that are selectively permeable to zirconium. What is the equilibrium potential for zirconium? • +60 mV, • -60 mV, • +90 mV, • -90 mV, • +120 mV, • -120 mV.
Question 2 • At the normal resting state there is no net current through the membrane. What is the Na/K pump doing? • nothing, • moving ions out, • moving ions in, • moving some ions in and moving others out
Question 3 During the action potential, the sodium current is terminated by the sodium inactivation gate. How is the potassium current terminated? • Potassium inactivation gate b. membrane voltage c. depletion of potassium ions, d. it’s not terminated
Question 4 • When a membrane is “charged” and maintains a voltage across it, most of the ions responsible for the charge are located just adjacent to the membrane. This distribution exists because: • The membrane is sticky for ions, • ions are repelled by the cytoplasm, • ions are attracted to the other side of the membrane, • ions like to accumulate near the ion-selective channels.
