This animation shows how neurons send and receive signals to communicate with one another at contact points called synapses.

Electrical impulses travel from neuron to neuron to transfer information. When an electrical impulse reaches the end of a neuron, it triggers the opening of channels that release calcium ions. The increase in calcium triggers the release of neurotransmitter molecules into the synapse. The neurotransmitter activates receptors on a second target neuron, opening channels that let sodium inside that neuron. The increase in sodium triggers an electrical impulse that travels across the target neuron.

This animation illustrates the process of signal transmission in three-dimensional detail. Depending on students’ backgrounds, it may be helpful to pause the animation at various points to discuss different features of the neurons.