Myelin sheaths are a highly important component involved in nervous transmission, enabling the rapid acceleration of action potentials. Myelin sheaths are formed from Schwann cells - these are electrically insulating layers of lipid bilayers, allowing the jumping, or saltatory conduction, or the wave of depolarisation. This is due to ions only being able to move in and out of the axon at the nodes of Ranvier between the Schwann cells, leading to a $$100\times$$ increase in the rate of transmission. This increase in the speed of transmission is vital in the survival of large and mobile organisms - if no myelin sheath were present, it would not be possible for reflexive actions to occur, as by the time the stimulus had caused damage, the signal would have only just reached the central nervous system. Many disease states affect the myelin sheath structures, reducing the speed of nervous transmission, including multiple sclerosis and Guillain-Barre syndrome, amongst others. This can lead to muscle weakness, loss of vision, and a loss of sensation and coordination. There is currently no known treatment - only management of the symptoms.