Question

During transmission of nerve impulse the potential inside membrane has the following type of charge

• A. First positive, then negative and back positive
• B. First negative, then positive and back negative
• C. First positive, then negative and remain negative
• D. First negative, then positive and remain positive

Answer 1

The correct option is B First negative, then positive and back negative

In the absence of a signal, the resting potential of the neuron is maintained by the potassium leak channels, which allow the flow of potassium ions out of the cell, resulting in a more negative charge in the cell when compared to outside the cell. In response to stimulation, the neuron initiates an action potential orchestrated by the opening and closing of voltage-gated ion channels.

First, depolarization of the membrane occurs, when the voltage-gated sodium channels are opened and there is a large influx of sodium ions.

Second, the sodium channels are rapidly inactivated and the voltage-gated potassium channels open, resulting in the efflux of potassium ions and the repolarization of the membrane.

Third, the voltage-gated potassium channels close and the potassium leak channels reestablish the resting membrane potential.

Thus, the correct answer is option B.