Depolarization of a stimulated nerve is maintained by

Which of the following statement/s is/are correct with respect to generation and conduction of nerve impulse?
i. The resting potential difference is $-70 \text{ mV}$.
ii. The voltage-gated $Na^{+}$ and $K^{+}$ channels operate together and are self-closing.
iii. At the peak of action potential,the potential difference rises to $+30$ to $+60 \text{ mV}$.
iv. In medullated nerve fibre,the action potential is conducted as a wave of membrane depolarization.
v. The resting potential is maintained by the closure of gated channels of $Na^{+}$ and $K^{+}$.

The potential difference across the membrane of a relaxed muscle fibre is called resting potential. It amounts to about

In the resting stage of a neuron,the concentration gradient is generated due to:

$A$ : The imbalance in the concentration of $Na^+, K^+$ and proteins generates the resting potential.
$R$ : To maintain the unequal distribution of $Na^+$ and $K^+$,the neurons use electrical energy.

Resting membrane potential is maintained by