Question

The depolarization of nerve membrane takes place through influx of ............ ions.

• A. Calcium
• B. Potassium
• C. Sodium
• D. Magnesium.

Answer 1

Answer: (C)

Depolarization is the loss of polarization; i.e, loss of the difference in charge between the inside and outside of the plasma membrane of a muscle or nerve cell due to a change in permeability and migration of sodium ions to the interior. When a stimulus of adequate strength is applied to a polarized membrane, the permeability of the membrane to Na+ is followed by the reversal of the polarity at that site, i.e, the outer surface of the membrane becomes negatively charged and the inner side becomes positively charged. The polarity of the membrane at the site is, thus reversed and said to be depolarized.

So, the correct answer is option C.