When does a neural impulse begin to travel along a myelinated neuron?

A neural impulse begins to travel along a myelinated neuron when an action potential occurs at a node of Ranvier. Myelinated neurons have a protective fatty covering called myelin that helps to insulate the axon and speeds up signal transmission through a process known as saltatory conduction.

In this process, the action potential does not travel continuously along the entire length of the axon but instead "jumps" from one node of Ranvier to the next. These nodes are small gaps in the myelin sheath where the axonal membrane is exposed. When an action potential occurs at one of these nodes, it triggers a rapid influx of sodium ions, which depolarizes the membrane and allows the impulse to move quickly to the next node. This jumping of the action potential between nodes significantly increases the speed of neural communication compared to unmyelinated neurons, where the impulse must travel continuously along the membrane.

Other options, such as increasing dopamine levels, activating sensory receptors, or being in a resting potential phase, do not directly initiate the traveling of a neural impulse along a myelinated neuron. Dopamine primarily functions as a neurotransmitter involved in signaling between neurons but does not directly cause action potentials in myelinated axons. Sensory