Question

The axoplasm inside the axon contains high concentration of _______ and ______

• A. $K^{+}$ and $N{a}^{+}$
• B. $K^{+}$ and negatively charged proteins
• C. $N{a}^{+}$ and $C{l}^{-}$
• D. Both (a) and (b)

Answer 1

Answer: (B)

The axoplasm inside the axon contains high concentration of K⁺ and negatively charged proteins and low concentration of Na⁺. In contrast, the fluid outside the axon contains a low concentration of K⁺, a high concentration of Na⁺ and thus form a concentration gradient. These ionic gradients across the resting membrane are maintained by the active transport of ions by the sodium-potassium pump which transports 3 Na⁺ outwards for 2 K⁺ into the cell.