After the peak of an action potential, membrane potential repolarises. Which best describes the events over the next few milliseconds membrane potential returns directly to resting potential (linearly) membrane potential falls to a value more negative than resting potential membrane potential returns to resting potential with a logarithmic decay membrane potential returns to resting potential with an exponential decay membrane potential falls to Potassium Equilibrium Potential
Question
After the peak of an action potential, membrane potential repolarises. Which best describes the events over the next few milliseconds membrane potential returns directly to resting potential (linearly) membrane potential falls to a value more negative than resting potential membrane potential returns to resting potential with a logarithmic decay membrane potential returns to resting potential with an exponential decay membrane potential falls to Potassium Equilibrium Potential
Solution 1
After the peak of an action potential, the membrane potential does not return directly to the resting potential. Instead, it undergoes a process called repolarization.
Here's a step-by-step breakdown of the process:
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The peak of the action potential is reached when the membrane potential becomes positive. This is due to the rapid influx of sodium ions (Na+) into the cell, which is facilitated by voltage-gated sodium channels.
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After the peak is reached, these sodium channels start to close, and voltage-gated potassium channels open. This allows potassium ions (K+) to flow out of the cell, which begins the process of repolarization.
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As K+ ions leave the cell, the membrane potential starts to become more negative, moving back towards the resting potential.
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However, the membrane potential doesn't just stop at the resting potential. Instead, it overshoots slightly and becomes hyperpolarized. This means that the membrane potential falls to a value more negative than the resting potential.
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This hyperpolarization is temporary. The membrane potential eventually returns to the resting potential due to the action of the sodium-potassium pump and leak channels, which help to maintain the resting potential.
So, the best answer to your question is: "membrane potential falls to a value more negative than resting potential".
Solution 2
After the peak of an action potential, the membrane potential does not return directly to the resting potential. Instead, it undergoes a process called repolarization.
Here's a step-by-step breakdown of the process:
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Peak of Action Potential: The membrane potential reaches its peak due to the influx of sodium ions (Na+) into the cell, which makes the inside of the cell more positive.
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Repolarization: After the peak, voltage-gated sodium channels close, stopping the influx of Na+. At the same time, voltage-gated potassium channels open, allowing potassium ions (K+) to flow out of the cell. This outflow of positive ions makes the inside of the cell more negative, causing the membrane potential to decrease (repolarize).
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Hyperpolarization: The membrane potential often falls to a value more negative than the resting potential. This is known as hyperpolarization. It occurs because the potassium channels stay open a bit too long, allowing more K+ to leave the cell than necessary.
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Return to Resting Potential: Finally, the membrane potential returns to the resting potential. This is not a linear or logarithmic decay, but rather an exponential one, as the membrane potential gradually stabilizes.
So, the best description of the events over the next few milliseconds after the peak of an action potential is: "membrane potential falls to a value more negative than resting potential" and then "membrane potential returns to resting potential with an exponential decay".
Similar Questions
8. The Action PotentialAn action potential is a large and rapid transient increase in membrane potential. It begins with themembrane potential at its resting level (i.e., at the resting potential). There is then an increase inmembrane potential from the resting level to a threshold potential. At this point there is a large and rapidincrease in membrane potential called a depolarisation. The membrane potential reaches a peak and thenbegins to decrease again. This decrease is called a repolarisation. At the end of the repolarisation phase,the membrane potential actually goes below the resting membrane potential. This is called ahyperpolarisation. Membrane potential then rises again to the resting potential level.9The changes in membrane potential during an action potential are the result of Na+ moving into the cellthrough voltage-gated Na+ channels and K+ moving out of the cell through voltage-gated K+ channels.In order for Na+ to move from the extracellular fluid (ECF) through the Na+ channel into the cytosol, itmust pass through two gates within the Na+ channel: first it must move through the activation gate andthen through the inactivation gate. The Na+ channel activation gate is closed when the membranepotential is at the resting level. As the membrane potential increases from the resting potential to thethreshold potential, activation gates in some Na+ channels begin to open. Once the membrane potentialreaches the threshold potential, the activation gates in all Na+ channels open (very rapidly).The Na+ channel activation gate will close again once the membrane potential falls back to the thresholdpotential during the hyperpolarisation phase.The inactivation gate in the Na+ channel is open at the resting membrane potential.As the depolarisation progresses and begins to approach the peak level of depolarization, the inactivationgate begins to close (they close slowly).The Na+ channel inactivation gate will open once more when the membrane potential begins to drop inthe early part of the repolarisation phase (just after the peak membrane potential has been achieved.In order for K+ to leave the cell it must pass through the activation gate in the K+ channel. Note that thereis only one activation gate in the K+ channel; there is no inactivation gate in the K+ channel.The K+ channel’s activation gate is closed at the resting membrane potential. It opens slowly during thedepolarisation phase.The K+ channel activation gate will close once more when the membrane potential begins to drop in theearly part of the repolarisation phase (just after the peak membrane potential has been achieved
dentify why the membrane becomes hyperpolarized following the repolarization phase of an action potential.Multiple choice question.Voltage-gated K+ channels remain open for a short period of time after reaching RMP; allowing K+ to diffuse out of the cell.Voltage-gated Na+ channels remain open for a short period of time after reaching RMP; allowing Na+ to diffuse out of the cell.Voltage-gated Na+ channels remain open for a short period of time after reaching RMP; allowing Na+ to diffuse into the cell.Voltage-gated K+ channels remain open for short period of time after reaching RMP; allowing K+ to diffuse into the cell.
During the depolarisation stage of an action potentialThe membrane potential returns to resting conditionsSodium (Na+) enters the cell down it's concentration gradientVoltage gated K+ channels are openPotassium (K+) enters the cell against its concentration gradient
When thinking about an action potential which one of the following statements is TRUE?Question 10Answera.A stimulus changes the permeability of a "patch" of the membrane, and sodium ions (Na+) diffuse rapidly into the cell.b.During repolarization, sodium ions diffuse rapidly into the cell.c.If a stimulus is strong enough, hyperpolarization causes membrane polarity to be completely reversed, and an action potential is initiated.d.Ionic conditions are restored after repolarization by the actions of the sodium-potassium (Na+-K+) pump, whereby two Na+ ions are ejected for every three K+ ions carried back into the cell.e.The external side of the resting membrane is slightly negative, and its internal side is slightly positive.
Which of the following helps create the refractory period for action potentials frequency in muscle and nerve cells?Group of answer choicesclosed activation gate on voltage gated sodium channelslag for restoration of resting membrane potential by sodium-potassium pumpinability to reach threshold potential for the cellclosed inactivation gate on voltage gated sodium channelsclosed gates on voltage gated potassium channels
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