ANATOMY

Detailed explanation-1: -These are the gaps formed between the myelin sheath where the axons are left uncovered. Because the myelin sheath is largely composed of an insulating fatty substance, the nodes of Ranvier allow the generation of a fast electrical impulse along the axon. This rapid rate of conduction is called saltatory conduction.

Detailed explanation-2: -The larger the diameter of the axon, the faster it transmits information. Some axons are covered with a fatty substance called myelin that acts as an insulator. These myelinated axons transmit information much faster than other neurons.

Detailed explanation-3: -Nodes of Ranvier are gaps in the myelin along the axons; they contain sodium and potassium ion channels, allowing the action potential to travel quickly down the axon by jumping from one node to the next.

Detailed explanation-4: -Increasing the number of myelin wraps lowers the capacitance along the internode, reducing the time required to charge the internodal membrane. This means that consecutive nodes of Ranvier reach threshold quicker and, therefore, the conduction velocity is increased.

Detailed explanation-5: -The nodes of Ranvier are characterized by short (1um), specialized regions in the axonal membrane that are not insulated by myelin. Although it is bare of myelin at the node, the axon is in direct contact with the microvilli of the Schwann cells in the PNS, or with processes of astrocytes in the CNS (Figure 1).