Which mineral is primarily associated with nervous system function?

• A. Sodium
• B. Potassium
• C. Calcium
• D. Magnesium

Answer: (A)

Nerve signals depend on moving charged particles across the neuron's membrane. The outside of a neuron has a higher concentration of sodium, while the inside has more potassium, thanks to the Na+/K+ pump that maintains these gradients. When a neuron is stimulated, voltage‑gated sodium channels open and sodium rushes into the cell. This rapid influx depolarizes the membrane, reaching a threshold that triggers an action potential that travels along the neuron. After the peak, potassium channels open to let K+ exit, helping restore the resting membrane potential, and the pump gradually reestablishes the original gradients.

Calcium is crucial for releasing neurotransmitters at the synapse, and magnesium plays supporting roles in enzyme activity and receptor function, but the mineral most directly linked to starting and propagating nerve impulses is sodium. Its role in depolarization is the key reason it’s the best answer.