Аннотация:The myelinated nerve fibre is a result of interaction of two different cell types: the axon, which is electrically excitable and is the main conductor of the action potentials, and the sheath of glial cells around the axon which form the myelin layer and which is believed to primarily serve as an electrical insulator essential for high speed of signal propagation. During prolonged activity, potassium ions released from the axon may accumulate in the narrow space between the axon and the myelin, and the purpose of this chapter is to construct a model of the processes by which potassium ions are cleared from the region near the axon and to study possible side-effects of these mechanisms. In particular, we shall discuss the role that changes in the structure of the myelin may play in this connection.