Question

In a resting neuron, the axon membrane is

• A. Impermeable to both N$a^{+}$ and $K^{+}$ ions
• B. Comparatively more permeable to N$a^{+}$ and nearly impermeable to $K^{+}$ ions
• C. Comparatively more permeable to $K^{+}$ and nearly impermeable to N$a^{+}$ ions
• D. Equally permeable to both N$a^{+}$ and $K^{+}$ ions

Answer 1

The correct option is C Comparatively more permeable to $K^{+}$ and nearly impermeable to N$a^{+}$ ions

Resting membrane is the condition in which there is no propagation of impulse. As the impulse passes from one part of the neuron to other the conductivity of the ions in the previous part decreases and the ion channels start closing. During this stage, k+ ion channels are opened as they slow workers and also called as lazy channels. They take more time to close and hence they remain open. Na+ channels are closed as the impulse passes off. Due to the presence of opened k+ channels, the permeability of k+ is more and as the Na+ channels are closed the membrane is impermeable to Na+. So the resting membrane of axon have more k+ inside and more na+ outside.

so, the correct option is (C)