Final answer:
Myelin increases the rate of nerve conduction by acting as an insulator and allowing action potentials to jump between the nodes of Ranvier in a process known as saltatory conduction, making impulse transmission faster and more energy-efficient compared to unmyelinated axons.
Step-by-step explanation:
The reason myelin increases the rate of nerve conduction is due to its role as an insulator for neuronal axons. Myelin sheaths prevent the dissipation of electrical signals, which allows action potentials to travel quickly along the axon. The key to this increased speed is the presence of nodes of Ranvier, which are gaps in the myelin sheath where ion channels are concentrated. These nodes facilitate saltatory conduction, where the action potential 'jumps' from one node to the next, rather than moving continuously along the axon. This mechanism results in much faster propagation of the nerve impulse compared to continuous conduction seen in unmyelinated axons, conserves energy, and reduces signal loss. Diseases such as multiple sclerosis can impair this process by damaging the myelin sheath, leading to slower nerve signal transmission and various neurological symptoms.