What makes a nerve impulse travel along an axon?

An action potential is a brief electrical pulse that travels along the axon of a neuron, allowing the neuron to communicate with other cells. The action potential is caused by the movement of sodium and potassium ions across the neuronal membrane. When a neuron is at rest, the inside of the membrane is negative compared to the outside. This is due to the fact that there are more sodium ions outside of the cell than there are inside the cell, and vice versa for potassium ions. When an action potential is triggered, the sodium channels in the membrane open, allowing sodium ions to rush into the cell. This causes the inside of the membrane to become positive, which in turn triggers the potassium channels to open. Potassium ions then rush out of the cell, restoring the negative charge inside the membrane. The action potential then travels down the axon, repeating this process until it reaches the synapse. At the synapse, the action potential causes the release of neurotransmitters, which are chemical messengers that transmit the signal to other cells.