Concept:Sodium ions
(Na+) are essential for generating and transmitting nerve impulses via the sodium‑potassium pump and action potentials.
Explanation:Nerve cells communicate by electrical signals called action potentials.
These signals rely on the movement of ions across the cell membrane.
Sodium ions
(Na+) are the primary cations responsible for depolarisation – the rapid rise in voltage that initiates a nerve impulse.
The sodium‑potassium pump maintains a high concentration of
Na+ outside the cell and a low concentration inside.
When a nerve is stimulated, voltage‑gated sodium channels open, allowing
Na+ to rush into the cell, creating the action potential.
This electrical signal travels along the neuron to transmit information.
Sodium also plays roles in regulating fluid balance and transporting nutrients like sugars and amino acids into cells.
In contrast, elements such as lithium, rubidium, and caesium are not directly involved in nerve signal transmission in the human body.
Answer:B. Sodium