how does myelin sheath help the nervous system
Myelin The main purpose of a myelin sheath is to increase the speed at which impulses propagate along the myelinated fiber. Along unmyelinated fibers, impulses continuously move as waves, but, in myelinated fibers, they "hop" or propagate by saltatory conduction. Myelin decreases capacitance and increases electrical resistance across the cell membrane (the axolemma). Thus, myelination prevents the electric current from leaving the axon. It has been suggested that myelin permits larger body size by maintaining agile communication between distant body parts.[2]
Central nervous system The central nervous system (CNS) is the part of the nervous system consisting of the brain and spinal cord. The central nervous system is so named because it integrates information it receives from, and coordinates and influences the activity of, all parts of the bodies of bilaterally symmetric animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish—and it contains the majority of the nervous system. Many consider the retina[2] and the optic nerve (cranial nerve II),[3][4] as well as the olfactory nerves (cranial nerve I) and olfactory epithelium[5] as parts of the CNS, synapsing directly on brain tissue without intermediate ganglia. As such, the olfactory epithelium is the only central nervous tissue in direct contact with the environment, which opens up for therapeutic treatments. [5] The CNS is contained within the dorsal body cavity, with the brain housed in the cranial cavity and the spinal cord in the spinal canal. In vertebrates, the brain is protected by the skull, while the spinal cord is protected by the vertebrae.[6] The brain and spinal cord are both enclosed in the meninges.[6] In central nervous system, the interneuronal space is filled with large amount of supporting non nervous cells called neuroglial cells.