Resting membrane potential

The figure shows part of a neuron with the following labeled:
● Sodium ion (Na+) and potassium ion (K+) concentrations (measured in mM)
● Resting membrane potential (-70 mV)
● Na+ channels (black boxes) and K+ channels (gray boxes)

The resting membrane potential of a neuron is -70 mV.  At rest a neuron has many more open K+ channels than open Na+ channels. However, at this time the rate of K+ moving out of the neuron is equal to the rate of Na+ moving into the neuron. Explain how K+ and Na+ can be moving across the membrane at the same rate if there are many more open K+ channels than open Na+ channels?

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This material is based upon work supported by the National Science Foundation (DUE grants: 1438739, 1323162, 1347740, 0736952 and 1022653). Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.