Multiple choice

During the transmission of nerve impulse through a nerve fibre, the potential on the inner side of the plasma membrane has which type of electric charge?

  1. First negative, then positive and continues to be positive

  2. First negative, then positive and again back to negative

  3. First positive, then negative and continues to be negative

  4. First positive, then negative and again back to positive

  5. It continues to be negative.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

As in resting potential 3Na+ remains at the outer side and 2K+ in the inner side of the plasma membrane. Hence, inner side is negative at the start and as impulse is transmitted through axon Na channels open and Na+ rushes in causing depolarization, i.e.  inside positive. When the impulse is transmitted completely, K channels open and K+ rushes out to cause repolarization, i.e. negative inside.

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