Question

During repolarisation of nerve

• A. $K^{+}$ gate close and $N{a}^{+}$ gate opens
• B. $N{a}^{+}$ channels close and $K^{+}$ channels are open
• C. Both gates remain open
• D. Bth $K^{+}$ and $N{a}^{+}$ gates are close

Answer 1

The correct option is B $N{a}^{+}$ channels close and $K^{+}$ channels are open

During repolarisation, $N{a}^{+}$ channels are closed. It occurs so that after depolarisation, no more $N{a}^{+}$ ions can enter the cell. After about 0.5 ms, permeability to $K^{+}$ ion increases because the build up of positive charge inside the cell opens voltage-gated $K^{+}$ channels.