The transfer of electrical signals by nerve cells in the human body is enabled by a combination of sodium and potassium. Nerve cells, also known as neurons, communicate with each other through electrical impulses. These impulses are generated and transmitted across the nerve cell membrane.

Sodium and potassium ions play a crucial role in this process. Neurons have specialized channels in their membrane that allow the movement of these ions. When a nerve impulse is generated, the membrane potential changes, causing specific sodium channels to open. This allows sodium ions to rush into the neuron, creating a positive charge inside the cell.

This influx of sodium ions generates an action potential, which propagates along the nerve cell. As the action potential moves, it triggers the opening of potassium channels, allowing potassium ions to flow out of the neuron. This movement helps restore the original membrane potential and repolarize the cell.

Therefore, both sodium and potassium ions are essential for the transfer of electrical signals in the nervous system. They work together to create and propagate nerve impulses, enabling communication between neurons.