Impulse propagation refers to the process by which an action potential, or nerve impulse, travels down an axon. Generally, an action potential tends to move in one direction along the axon, from the cell body towards the axon terminal. This is due to the fact that certain ions flow into and out of the axon in response to electric stimuli, creating an electrical potential difference that pushes the impulse towards the end of the axon. However, it is possible for an action potential to move in more than one direction along the axon under certain conditions, such as when the axon is depolarized prematurely due to injury or disease.