Biology

Difference between depolarization and repolarization

Main difference

The main difference between depolarization and repolarization is that depolarization is the loss of the resting membrane potential due to the conversion of cell membrane polarization, while repolarization is the restoration of the resting membrane potential after each occurrence of depolarization …

Depolarization versus repolarization

Depolarization is the change of the cell membrane potential to an additional positive value; on the other hand, repolarization is the conversion into membrane potential resorting to the negative value. The cell membrane consists of positive charges on depolarization, while the cell membrane has a negative charge on repolarization. During depolarization, the inner membrane becomes less negative and more positive, while, during repolarization, the negative charge on the inner membrane returns.

Depolarization is used to increase the membrane potential; on the other hand, repolarization is the process of restoring the resting membrane potential by decreasing the membrane potential. Depolarization helps drive an action potential on the cell membrane; on the contrary, repolarization prevents the impulse of an action potential. Voltage-gated “m” sodium channels are used in depolarization; On the other hand, voltage-gated “n” potassium channels and various other potassium channels (type A channels, delayed rectifiers, and Ca 2+ -gapped K + channels ) are used in repolarization.

Depolarization occurs due to the opening of sodium channels; on the contrary, repolarization is produced by the opening of the potassium ion channels and the closure of the sodium channels. Depolarization generally results in excitation of effector organs, eg, muscle contractions; on the other hand, repolarization does not usually lead to stimulation of the effector organ. There is less polarity present in the cell membrane in depolarization, while more polarity is present in the cell membrane in repolarization.

The resting membrane potential is not restored on depolarization; on the other hand, the resting membrane potential returns repolarization. Depolarization generally activates a mechanical activity, whereas repolarization generally does not activate a mechanical activity. The value of the membrane potential in depolarization in the cell membrane is -70 mV; on the other hand, the value of the membrane potential in repolarization in the cell membrane is + 50 mV.

Comparative chart

Depolarization Repolarization
Depolarization is considered as an activating method that takes place in the cell membrane that changes its polarization. Repolarization is the procedure of returning the cell membrane to the resting membrane potential.
Net charge
It consists of positive charges on the cell membrane. The cell membrane has negative charges.
Change in membrane potential
The inner membrane becomes less negative and more positive. The negative charge on the inner membrane returns.
Membrane potential
It used to increase the membrane potential. The process of restoring the resting membrane potential lowers the membrane potential.
Action potential
Helps drive an action potential on the cell membrane. Avoid the impulse of an action potential
Channels used
Voltage-gated “m” sodium channels are used. Voltage-gated “n” potassium channels and various other potassium channels are used.
Ion channels
Caused by the opening of sodium channels. Produced by the opening of potassium ion channels and the closure of sodium channels.
Importance
It generally results in exciting effector organs, for example muscle contractions. It usually does not result in stimulation of the effector organ.
Cell membrane potential
They have less polarity in the cell membrane. There is more polarity present in the cell membrane.
Membrane potential at rest
The resting membrane potential is not restored. The resting membrane potential returns.
Mechanical activity
Generally activates a mechanical activity. It usually does not activate a mechanical activity.
Potential value
The value of the membrane potential at the cell membrane is -70 mV. The value of the membrane potential at the cell membrane is + 50 mV.
What is depolarization?

The term depolarization is defined as depolarization is the loss of resting membrane potential due to the conversion of cell membrane polarization. The resting membrane potential is considered the potential across the resting cell membrane, which is usually -70 mV. Therefore, it tests that the inside of the cell has a more negative charge than the charge present outside the cell.

There is less polarity in the cell membrane in depolarization, and generally activates a mechanical activity of the cell membrane. Action potentials generally occur when the neuron’s protein channels are released into its membrane. Voltage-gated “m” sodium channels are used in depolarization.

A depolarization current is produced by the opening of sodium channels when an action potential needs to be accelerated; This allows more sodium ions to enter the cell. When more sodium ions enter the cell; this generally results in the decrease of the negative charges present inside the cell. The action potential generally accelerates when the resting membrane potential reaches -55 mV.

The membrane potential when it crosses the cell membrane reaches +30 mV; this results in the transmission of the nerve impulse in the method of an action potential. Depolarization generally results in the excitation of the effector organs, for example, muscle contractions. The entire occurrence from depolarization to repolarization occurs in approximately two milliseconds, allowing neurons to have a vigorous action potential in rapid bursts by allowing neuronal communication.

The resting membrane potential is conserved by
  • The constant dispersal of potassium ions outside the cell.
  • The completion of the sodium-potassium pump, which propels three sodium ions out of the cell, while carrying two potassium ions into the cell.
  • The presence of more negatively charged ions, for example, phosphate ions and proteins within the cell.

What is repolarization?

The term repolarization is defined as the restoration of the resting membrane potential after each occurrence of depolarization. Repolarization is generally the occurrence whereby the membrane potential is recharged to its original resting membrane potential through depolarization at the cell membrane.

The sodium channels that cause the least negative charge within the cell membrane on depolarization and excited the resting membrane potential to the action potential, are closed and now have open potassium channels due to the presence of more positive ions within the cell membrane, resulting in the transport of potassium ions out of the cell making the inside of the cell more negative. Now, at last, the repolarization process restores the resting membrane potential.

A cell usually recovers this form, or generally repolarizes the situation, opening a protein push in the membrane, which is known as a sodium-potassium pump. In this pump, for every three sodium ions, it pumps two potassium ions. The pumps continue to do this until the proper charge is obtained within a cell.

Unlike the occurrence of depolarization, repolarization generally does not activate any mechanical activity through stimulation of the effector organ, such as muscles. However, repolarization is necessary for the transmission of the second nerve impulse through depolarization a second time when preparing the cell membrane.

Repolarization eventually results in the hyperpolarization stage in which the membrane potential develops with an extra negative charge compared to the previous resting potential. Hyperpolarization is normally due to diffusion of K + ions from K + channels outside the cell membrane or to the influx of Cl– ions from Cl– channels.

Key differences
  1. Depolarization is known as the alteration of the cell membrane potential to an additional positive value, while repolarization is known as the change in membrane potential through the frequent negative value.
  2. In depolarization, the cell membrane contains positive charges, while in repolarization, the cell membrane contains a negative charge.
  3. The inner membrane becomes less negative and more positive during depolarization, while during repolarization, the negative charge on the inner membrane enters.
  4. The membrane potential usually increases through the depolarization process; on the other hand, repolarization is used to restore the resting membrane potential by means of drops in membrane potential.
  5. In depolarization, the value of the membrane potential is -70 mV at the cell membrane; on the other hand, in repolarization, the value of the membrane potential is + 50 mV at the cell membrane.
  6. In depolarization, there is a minimal polarity existing in the cell membrane, while in repolarization, there is a maximum polarity present in the cell membrane.
  7. The action potential on the cell membrane is enhanced with the help of the depolarization process; on the contrary, repolarization prevents the development of an action potential.
  8. In depolarization, the channels used are usually voltage-gated “m” sodium channels; on the other hand, in repolarization, the channels used are generally voltage-gated potassium “n” channels and many other potassium channels.
  9. By opening the sodium channels, depolarization occurs; conversely, by opening potassium ion channels and closing sodium channels, repolarization is formed.
  10. Depolarization generally affects the excitation of many effector organs such as muscle contractions; on the other hand, repolarization generally does not result in the speed of the effector organ.
  11. In depolarization, the resting membrane potential is not regenerated; on the other hand, in repolarization, the resting membrane potential is regenerated.
  12. Depolarization triggers a mechanical action, whereas repolarization generally does not initiate a mechanical action.

Final Thought

The above discussion concludes that the cell membrane consists of positive charges on depolarization, while the cell membrane has a negative charge on repolarization. During depolarization, the inner membrane becomes less negative and more positive, while, during repolarization, the negative charge on the inner membrane returns.

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