Question

Which one of the following sets of ions is necessary for transmission of nerve impulse?

• A. N$a^{+}$ and $K^{+}$
• B. C$a^{2+}$ and N$a^{+}$
• C. C$a^{2+}$ and $K^{+}$
• D. N$a^{+}$ and M$g^{2+}$

Answer 1

Answer: (A)

N$a^{+}$ and $K^{+}$

The arrival of the threshold stimulus is responsible for changing the permeability of the membrane of the axon to the sodium ions. The influx of the Na${}^{+}$ ions causes depolarization of the membrane that causes generation of the impulse. The depolarization is followed by the repolarization due to efflux of the K${}^{+}$. This ultimately leads to the hyperpolarization and the activity of the Na${}^{+}$-K${}^{+}$ pump is needed to restore the polarized state of the axon membrane.

Hence, the correct answer is 'Na${}^{+}$ and K${}^{+}$'