Question

Select the option responsible for restoring the resting membrane potential of a neuron
(a) Voltage-gated ${ Na }^{+}$ channels
(b) Voltage-gated ${ K }^{+}$ channels
(c) Leaky channels for ${ K }^{+}$
(d)${ Na }^{+}$/${ K }^{+}$ pump

Answer 1

Hint: The membranes of neurons are polarised with the electrical potential difference that’s why neurons remain in an excited state and conduction of impulse takes place from one neuron to another neuron.

Complete answer:
When conduction of impulse does not take place between neuron, the axonal membrane becomes more permeable to potassium ions and impermeable to sodium ions, whereas axoplasm inside axon contains a high concentration of potassium ion with negatively charged proteins and low concentration of sodium ions, because of this potential difference obtain with electrically positive ions outside and negative ions inside. This type of potential difference across the plasma membrane is called a resting membrane. The average value of the resting membrane potential is 70mV.

Additional Information: In the case of depolarization, when the conduction of impulse gets stimulated, the axon reaches an excited state. Exchange of ions is initiated and the membrane becomes permeable to sodium ions which results in a balance of sodium and potassium ion across the membrane. Depolarization generates action potential and conduction of impulse initiated, whereas repolarization initiated with an increase in the concentration of sodium ions inside nerve cells, permeability of sodium ions across the membrane decreases, and that of potassium ions increases.
In the case of the sodium-potassium pump, the exchange of ions takes place against the concentration gradient where sodium ions expel out with the entry of potassium ions.
So, the correct answer is ${ Na }^{+}$/${ K }^{+}$ Pump.

Note: Refractory period is the time gap in repolarization where the nerve cannot stimulate and restoration of resting potential take place. The refractory period is unidirectional, where the impulse travels only in the forward direction. This period is short and takes only about 1 millisecond which results in a conduction of 1000 impulse per second.