Nervous System: Neuron, Synapse, Reflexes · Zoology

The resting membrane potential of a typical neuron is approximately -70 mV. This is primarily established by:

Rapid influx of Na⁺ through voltage-gated channels at rest
High K⁺ permeability via leak channels plus the Na⁺/K⁺ pump
Large negatively charged intracellular proteins that dominate the resting potential entirely
Equal distribution of Cl⁻ ions across the membrane creating a Donnan equilibrium

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Correct answer: High K⁺ permeability via leak channels plus the Na⁺/K⁺ pump

At rest, the membrane is much more permeable to K⁺ than to Na⁺. The outward leakage of K⁺ through leak channels, combined with the Na⁺/K⁺ pump (which exports 3 Na⁺ for every 2 K⁺ imported), maintains the negative interior at approximately −70 mV.

Difficulty: Medium Question 15 of 20

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The resting membrane potential of a typical neuron is approximately -70 mV. This is primarily established by:

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