- myelin sheath
An insulating layer surrounding vertebrate peripheral neurons, that dramatically increases the speed of conduction. It is formed by specialized Schwann cells, that can wrap around neurons up to 50 times. The exposed areas are called nodes of Ranvier: they contain very high densities of sodium channels, and action potentials jump from one node to the next, without involving the intermediate axon, a process known as saltatory conduction.
Dictionary of molecular biology. 2004.
Look at other dictionaries:
myelin sheath — n a layer of myelin surrounding some nerve fibers called also medullary sheath * * * the cylindrical covering on the axons of some neurons; it consists of concentric layers of myelin, formed in the peripheral nervous system by the plasma membrane … Medical dictionary
myelin sheath — noun a layer of myelin encasing (and insulating) the axons of medullated nerve fibers • Syn: ↑medullary sheath • Hypernyms: ↑sheath, ↑case • Part Holonyms: ↑medullated nerve fiber, ↑ … Useful english dictionary
myelin sheath — noun Date: 1896 a layer of myelin surrounding some nerve fibers called also medullary sheath … New Collegiate Dictionary
myelin sheath — my′elin sheath n. anat. zool. a discontinuous wrapping of myelin around certain nerve axons, serving to speed nerve impulses to muscles and other effectors • Etymology: 1895–1900 … From formal English to slang
myelin sheath — Anat. a wrapping of myelin around certain nerve axons, serving as an electrical insulator that speeds nerve impulses to muscles and other effectors. See diag. under neuron. [1895 1900] * * * … Universalium
myelin sheath — noun An envelope of myelin that surrounds nerve fibres … Wiktionary
myelin sheath — /maɪələn ˈʃiθ/ (say muyuhluhn sheeth) noun the layer of myelin encasing the axon of a nerve fibre, serving to insulate the nerve and to facilitate nerve impulses … Australian English dictionary
myelin sheath — A fatty material surrounding a nerve fiber … Dictionary of invertebrate zoology
myelin sheath — coating on the axons of nerve cells … English contemporary dictionary
Myelin sheath gap — Drawing of a peripheral nerve axon (labeled axis cylinder ), showing a node of Ranvier along with other features … Wikipedia