Question

Given are steps through which initiation and conduction of nerve impulse along the nerve fibre occurs. In which of following steps the influx of Na+ stops and outflow of K+ starts?

• A. A and C
• B. A and B
• C. B only
• D. C only

Answer 1

The correct option is D C only

Among the given figures, A represents polarization, B represents depolarization and C represents repolarization of nerve fibre. In repolarisation state, with the increase of sodium ions inside the nerve fibre, the membrane becomes less permeable to sodium ions and more permeable to potassium ions, which stops $N{a}^{+}$ influx and begins $K^{+}$ outflow.