Question

Assertion :For about 0.4 millisecond the nerve can not pickup new impulse. Reason: During refractory period concentration of $K^{+}$ is more on inside and $N{a}^{+}$ more on outside.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Assertion is incorrect but Reason is correct.

Answer 1

The correct option is C Assertion is correct but Reason is incorrect.

The refractory period is the time between two consecutive action potential during which sodium and/or calcium channels are inactivated and are irresponsive to any amount of amount of excitatory signal. This is because the membrane is depolarised and more $N{a}^{+}$ ions are present inside than the $K^{+}$ ions. Once the membrane restores the resting potential, these inactivated channels are opened to facilitate the new action potential. The assertion is correct but reason is incorrect. So, the correct answer is option C.