Question

multiple choice 2 points

when the voltage of a plasma membrane shifts from \\(+35\text{ mv}\\) toward \\(0\text{ mv}\\), the cell is ______.

reaching the threshold
repolarizing
depolarizing
exiting the threshold
hyperpolarizing

Explanation:

Define membrane potential phases

Using the Membrane Potential and Action Potential Phases knowledge points

• Depolarization: Membrane potential becomes more positive (e.g., from \(-70\text{ mV}\) toward \(+35\text{ mV}\)).
• Repolarization: Membrane potential returns toward the resting potential, becoming more negative (e.g., from \(+35\text{ mV}\) toward \(0\text{ mV}\) and then back to \(-70\text{ mV}\)).
• Hyperpolarization: Membrane potential becomes more negative than the resting potential (e.g., below \(-70\text{ mV}\)).

Analyze the given voltage shift

Using the Action Potential Phases knowledge point

• The voltage shifts from \(+35\text{ mV}\) toward \(0\text{ mV}\).
• Since the potential is moving in the negative direction back toward the resting state, this phase is repolarization.

Answer:

• reaching the threshold
• repolarizing (Correct answer)
• depolarizing
• exiting the threshold
• hyperpolarizing