Question

When the action potential begins, sodium gates open, allowing sodium ions to cross the membrane. Now the polarity changes to

• A. negative outside and positive inside
• B. positive outside and negative inside
• C. there is no difference in charge between outside and inside
• D. any one of the above could be correct

Answer 1

The correct option is A negative outside and positive inside

An action potential is a transient, electrical signal, which is caused by a rapid change in resting membrane potential (-70 mV). This occurs when the threshold potential (-55 mV) is reached, this causes a rapid opening in the voltage-gated sodium channels leading to an influx of sodium ions into the cell. This leads to +ve polarity inside the cell and negative polarity outside the cell.

So, the correct answer is 'negative outside and positive inside'.