Q160 / 200 · NEET 2011 (Screening) · Zoology

When a neuron is an resting state, $i e$, not conducting any impulse, the axonal membrane is

  • A
    equally permeable to both $\mathrm{Na}^{+}$and $\mathrm{K}^{+}$ions
  • B
    impermeable to both $\mathrm{Na}^{+}$and $\mathrm{K}^{+}$ions
  • Correct answer
    C
    comparatively more permeable to $\mathrm{K}^{+}$ions and nearly impermeable to $\mathrm{Na}^{+}$ions
  • D
    comparatively more permeable to $\mathrm{Na}^{+}$ions and nearly impermeable to $\mathrm{K}^{+}$ions

Solution

Neurons are excitable cells because their membrane are in a polarised state. Different types of selectively permeable channels are present on the neural membrane. When a neuron is not conducting any impulse, ie, resting, the axonal membrane is comparatively more permeable to potassium ion $\left(\mathrm{K}^{+}\right)$and nearly impermeable to sodium ion $\left(\mathrm{Na}^{+}\right)$.

Hence, the correct answer is option: 'C'.

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