Myelin sheaths around axons allow saltatory conduction, where action potentials "jump" from one node of Ranvier to the next. This increases conduction velocity and is more energy efficient than action potentials propagating along the entire length of the axon. At synapses, the gap between neurons is bridged by neurotransmitters releasing from the presynaptic axon and signaling to the postsynaptic dendrite of the next neuron.