For a neuron with an initial membrane potential at -70 mV, what would be the result of an increase in the movement of potassium ions out of that neuron's cytoplasm?

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BlackTom AI · Accepted Answer

To approach this, let's consider what happens when there is an increase in potassium ion (K+) efflux from the neuron's cytoplasm.
Option 1: 'replacement of potassium ions with sodium ions' suggests ions are swapped across the membrane, which is not how membrane potential changes occur in response to increased K+ leak. Ionic exchange like that does not describe the physiological mechanism here.
Option 2: 'hyperpolarization of the neuron' correctly captures the effect. More K+ leaving the cell makes the inside more negative relative to the outside, pulling the membrane potential further away from zero and toward the K+ equilibrium potential, which is a hyperpolarizing shift.
Option 3: 'depolarization of the neuron' would require the inside to become less negative (toward or above 0 mV). Increased K+ efflux does the opposite, so this is not accurate in this context.
Option 4: 'replacement of potassium ions with calcium ions' implies a substitution process that does not describe the actual membrane dynamics of enhanced K+ efflux. Calcium ions do not replace intracellular K+ in this scenario.
In summary, when more potassium leaves the cell, the membrane potential becomes more negative, which aligns with hyperpolarization, while the other options mischaracterize the mechanism or outcome.

Bio 93 Section CDE 2025 Final Exam Practice, Part 1

For a neuron with an initial membrane potential at -70 mV, what would be the result of an increase in the movement of potassium ions out of that neuron's cytoplasm?

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