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Questions and Answers
Depolarization occurs because...
Depolarization occurs because...
- More sodium ions diffuse into the cell than potassium ions diffuse out of it. (correct)
- The increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
- Potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
- The extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value.
- The inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases.
Repolarization occurs because...
Repolarization occurs because...
- More sodium ions diffuse into the cell than potassium ions diffuse out of it.
- The increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
- The inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases.
- The extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value.
- Potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close. (correct)
Hyperpolarization, or afterpotential occurs because...
Hyperpolarization, or afterpotential occurs because...
- The extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value.
- The increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level. (correct)
- Potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
- The inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases.
- More sodium ions diffuse into the cell than potassium ions diffuse out of it.
After the passage of the action potential, the sodium-potassium pump reestablishes the resting membrane potential.
After the passage of the action potential, the sodium-potassium pump reestablishes the resting membrane potential.
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The sodium-potassium pump uses bulk transport to move the sodium and potassium ions.
The sodium-potassium pump uses bulk transport to move the sodium and potassium ions.
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Study Notes
Action Potentials
- Depolarization: A process triggered by more sodium ions entering the cell compared to potassium ions exiting, resulting in a less negative membrane potential.
- Repolarization: Occurs as potassium ions continue to efflux after sodium channels close, contributing to a return to resting membrane potential.
- Hyperpolarization (Afterpotential): Caused by prolonged potassium permeability, resulting in a more negative membrane potential than the resting value before stabilizing.
Sodium-Potassium Pump
- The sodium-potassium pump plays a crucial role in restoring the resting membrane potential after an action potential.
- It does not utilize bulk transport; instead, it relies on active transport mechanisms to move sodium and potassium ions across the membrane.
Key Concepts
- Voltage-gated Sodium Channels: Inactivation gates close, leading to reduced sodium influx and cessation of depolarization.
- Potassium Ion Efflux: The continuous outflow during repolarization contributes to a brief hyperpolarization phase.
- Restoration of Resting Potential: The pump's activity is essential for redistributing ions and maintaining the electrochemical gradient across the neuronal membrane.
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Description
Test your understanding of action potentials with these flashcards from Lecture 3. This set focuses on the processes involved in depolarization and ion diffusion in nerve cells, specifically the movement of sodium and potassium ions. Perfect for students looking to cement their knowledge in neuroscience.
