Question

What is the function of ion channels in conduction of nerve impulse?

• A. Maintenance of concentration gradient of ions
• B. Maintenance and change in electric potential
• C. Transport of Na ion to the inner side of the membrane
• D. All of the above

Answer 1

The correct option is D All of the above

The conduction of nerve impulse occurs through the axon due to the movement of sodium and potassium ion across the cell membrane. Ion channels use energy to form and maintain a concentration difference of ions between the cell’s cytoplasm and the extracellular fluid. This concentration gradient results in a net negative charge on the inside of the membrane and a positive charge on the outside of the nerve cell. The membrane is called to be polarised. This difference causes a potential difference across the membrane. These ionic gradients across the resting membrane are maintained by the active transport of ions by the sodium-potassium pump/channel.

When a stimulus is applied at a site on the polarised membrane, the membrane at the site becomes freely permeable to $N{a}^{+}$. This leads to opening of $N{a}^{+}$ channels and results in a rapid influx of $N{a}^{+}$ followed by the reversal of the polarity at that site called a depolarized state.

After this the sodium ion channels will close, this results in the increase of positive ions within the cell. Thus the potassium channels will open again and the potassium ions will move out. This would result in achieving the resting membrane potential. This phase is called the repolarisation. Thus the polarised neuron gets depolarised on applying a stimulus. Then it gets repolarised. This way the impulse in conducted through the axon.

Hence, the functions of ion channels in conduction of nerve impulse include:

• Maintenance of concentration gradient of sodium potassium ions
• Maintenance and change in electric potential
• Transport of Na ion to the inner side of the membrane
• Transport of K ion to the outside side of the membrane