Question

Which of the following act is responsible for the depolarization of the neuron ?

• A. Closure of voltage gated $N{a}^{+}$ channel
• B. Opening of voltage gated $K^{+}$ channel
• C. Closure of voltage gated $K^{+}$ channel
• D. Opening of voltage gated $N{a}^{+}$ channel

Answer 1

The correct option is D Opening of voltage gated $N{a}^{+}$ channel

When a stimulus is applied at any site on the polarized membrane, the membrane at that site becomes freely permeable to $N{a}^{+.}$
This leads to a rapid influx of $N{a}^{+}$ followed by the reversal of the polarity at that site, which means the outer surface of the membrane becomes negatively charged and the inner side becomes positively charged.
The polarity of the membrane at the site gets reversed and hence depolarization takes place. So, opening of voltage gated Na+ ion channel causes depolarization of the neuron.

So, the correct answer is- option b.