A Node of Ranvier is a small gap in the myelin sheath that surrounds a nerve fiber. This sheath is made up of cells called Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. The nodes play a crucial role in the conduction of electrical impulses along the nerve, allowing for faster transmission. These nodes facilitate a process called saltatory conduction, where the electrical signal jumps from one node to the next. This increases the speed of nerve signal transmission, making communication between neurons more efficient and enabling rapid responses in the body.