Question

Which of these processes occurs during repolarization of nerve fibre?
(i) Open Na${}^{+}$ channel
(ii) Closed Na${}^{+}$ channel
(iii) Closed K${}^{+}$ channel
(iv) Open K${}^{+}$ channel

• A. (ii) and (iv)
• B. (i) and (iii)
• C. (ii) and (iii)
• D. (i) and (ii)

Answer 1

The correct option is A (ii) and (iv)

Polarization events help in the conduction of nerve impulses between nerve cells. Depolarization and repolarization are the phases during nerve transmission.

• In depolarization, the charge of the inner side of the membrane shifts from negative to positive by opening sodium influx and potassium ex-flux out of the cell.
  
• Repolarization is the shift of charge of the inner side of the membrane from positive to negative by the closing movement of Na and K influx in the cell. So, the correct answer is option A.