regulation of membrane repolarization during action potential

Definition

Target type: biologicalprocess

Any process that modulates the rate, frequency or extent of membrane repolarization during an action potential. Membrane repolarization is the process in which membrane potential changes in the repolarizing direction, towards the resting potential. [GOC:dos, GOC:dph, GOC:tb, ISBN:978-0-07-139011-8]

Membrane repolarization is a critical step in the action potential, following depolarization. It's the process by which the membrane potential of a neuron or muscle cell returns to its resting state after being depolarized. This is achieved by the efflux of positively charged ions, primarily potassium (K+), out of the cell.

Here's a detailed breakdown of the process:

1. **Sodium Channels Inactivate:** As the membrane potential depolarizes, the sodium channels responsible for the influx of sodium ions begin to inactivate. This stops the further entry of sodium ions into the cell.

2. **Potassium Channels Open:** Simultaneously, voltage-gated potassium channels open. These channels are activated by the depolarization, allowing potassium ions to flow out of the cell down their electrochemical gradient.

3. **Potassium Efflux:** The efflux of potassium ions carries positive charge out of the cell, restoring the negative charge inside the cell. This leads to a gradual decrease in the membrane potential, moving it back towards the resting potential.

4. **Hyperpolarization:** Due to the continued outward flow of potassium ions, the membrane potential can briefly become even more negative than the resting potential, a state known as hyperpolarization. This temporary hyperpolarization helps prevent the neuron from firing another action potential immediately.

5. **Sodium-Potassium Pump:** The sodium-potassium pump, an active transporter protein, actively pumps three sodium ions out of the cell and two potassium ions into the cell. This maintains the concentration gradients of sodium and potassium ions, ensuring that the membrane potential can be restored to its resting level.

6. **Repolarization Completed:** The combination of potassium channel activation, potassium efflux, and the activity of the sodium-potassium pump brings the membrane potential back to its resting value.

In essence, membrane repolarization is a carefully orchestrated process involving the inactivation of sodium channels, the activation of potassium channels, and the action of the sodium-potassium pump. This ensures the rapid and efficient restoration of the membrane potential to its resting state, allowing the neuron or muscle cell to be ready for another action potential.'
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Proteins (2)

Compounds (6)