During a nerve impulse, At the end of the axon from which the impulse is coming, the membrane depolarizes, gated ion channels open, and calcium ions (Ca2+) are allowed to enter the cell. When the calcium ions rush in, a chemical called a neurotransmitter is released into the synapse. The neurotransmitter binds with receptors on the neuron. A saltatory conduction is the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.