Final answer:
No, in saltatory conduction, not every section of the axolemma needs to depolarize to generate an action potential. The depolarization 'jumps' from node to node, allowing for faster propagation of the action potential along myelinated neurons.
Step-by-step explanation:
In saltatory conduction, the action potential does not depolarize every segment of the axolemma. Instead, it essentially 'jumps' from one node of Ranvier to another, skipping the myelinated sections of the axon. Myelination increases the speed of action potential propagation because the depolarization occurs only at the nodes of Ranvier where there are high concentrations of voltage-gated channels. In saltatory conduction, the sodium ions enter the neuron at the initial segment and then spread along the myelinated axon segment until reaching the next node of Ranvier. The depolarization must reach the next node to maintain a threshold potential for the action potential to continue its journey along the axon. This optimized spacing of the nodes allows for rapid and efficient transmission of neural signals without the need for every part of the axolemma to depolarize.