Continuing with the anatomical and physiological outline of the neuron and nerve fiber, the synapse was introduced. The nerve impulse was shown to be a depolarization of the neuron by the movement of positive ions through the cell membrane. The polarized nerve cell was drawn, and then how depolarization occurs due to a stimulus applied to the neuron. The nerve transmission was described as an electric current, flowing along the membrane. We viewed the process on a short video, which helped explain the movement of the ions into and out of the nerve cell.