Depolarization of a cell membrane occurs becauseMultiple ChoiceSodium ions are blocked from entering the cellMore sodium ions diffuse into the cell than potassium ions diffuse out of itThe concentration of sodium and potassium ions in the extracellular fluid is at equilibriumThe concentration of sodium and potassium ions in the cell is at equilibrium
Question
Depolarization of a cell membrane occurs becauseMultiple ChoiceSodium ions are blocked from entering the cellMore sodium ions diffuse into the cell than potassium ions diffuse out of itThe concentration of sodium and potassium ions in the extracellular fluid is at equilibriumThe concentration of sodium and potassium ions in the cell is at equilibrium
Solution
Depolarization of a cell membrane occurs because more sodium ions diffuse into the cell than potassium ions diffuse out of it.
Here's a step-by-step explanation:
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In a resting state, the inside of the neuron is negatively charged compared to the outside. This is due to a higher concentration of sodium ions outside the cell and a higher concentration of potassium ions inside the cell.
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When a stimulus reaches a resting neuron, the gated ion channels on the resting neuron's membrane open suddenly and allow the sodium ions, which are positively charged, to rush into the neuron.
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This influx of sodium ions causes the inside of the neuron to become more positively charged than the outside, creating an action potential. This change in charge is the depolarization of the cell membrane.
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After the influx of sodium ions, the sodium channels close and potassium channels open, allowing potassium ions to flow out of the neuron. This restores the negative charge inside the neuron, a process known as repolarization.
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The sodium-potassium pump then actively transports sodium ions out of the cell and potassium ions back into the cell to restore the original concentration of ions. This is the resting state of the neuron, ready for the next action potential.
So, the correct answer is: More sodium ions diffuse into the cell than potassium ions diffuse out of it.
Similar Questions
Depolarization of the cell membrane occurs when there is a rapid influx (inflow) ofMultiple Choicecalcium ions.amino acids.sodium ions.potassium ions.chloride ions.
Depolarization occurs becauseMultiple Choicepotassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.more sodium ions diffuse into the cell than potassium ions diffuse out of it.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.the inactivation gates of the voltage-gated sodium ion channels begin to open, and the diffusion of sodium ions decreases.
Depolarization of a cell membrane occurs because
A recently depolarized area of a cell membrane cannot generate an action potential because of theMultiple Choiceabsolute refractory period.high concentration of sodium ions in the extracellular fluid.the high concentration of potassium ions in the cytoplasm.presence of receptor sites on the membrane.
What is produced when depolarization of a cell membrane reaches threshold?Multiple ChoiceA new action potential is produced.An existing action potential is stopped.Voltage-gated ion channels close.The absolute refractory period ends.
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