myelin sheath

noun

Definition of myelin sheath

: the insulating covering that surrounds an axon with multiple spiral layers of myelin, that is discontinuous at the nodes of Ranvier, and that increases the speed at which a nerve impulse can travel along an axon

called also medullary sheath

Examples of myelin sheath in a Sentence

Recent Examples on the Web Without the myelin sheath, signals that go through a nerve are slowed or lost, which causes the nerve to malfunction. Aarti Sarwal, The Conversation, "Rare neurological disorder, Guillain-Barre Syndrome, linked to COVID-19," 7 July 2020 Both widening of the nodal gap and thinning of the myelin sheath slow the speed of impulse transmission. R. Douglas Fields, Scientific American, "The Brain Learns in Unexpected Ways," 12 Mar. 2020 When the protective covering on nerve fibers (also known as the myelin sheath) is worn away from this damage, the nerves don't work how they're supposed to, causing communication errors between the brain and body. Amy Marturana Winderl, SELF, "8 Early Symptoms of Multiple Sclerosis Women in Their 20s and 30s Should Know," 1 Mar. 2020 In another study, Rathmell and colleagues added dichloroacetate, which suppresses glycolysis, to the drinking water of mice that have a condition that mimics multiple sclerosis, in which the immune system attacks nerves' insulating myelin sheath. Mitch Leslie, Science | AAAS, "To treat some diseases, researchers are putting immune cells on a diet," 29 Mar. 2018 The brain is almost 60 percent fat, and each neuron requires a fatty myelin sheath to transmit impulses. Sophie Weiner, Popular Mechanics, "How Just Two Drops of Organic Mercury Can Destroy Your Brain," 15 Dec. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'myelin sheath.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of myelin sheath

1891, in the meaning defined above

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The first known use of myelin sheath was in 1891

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Cite this Entry

“Myelin sheath.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/myelin%20sheath. Accessed 1 Dec. 2020.

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More Definitions for myelin sheath

myelin sheath

noun

Medical Definition of myelin sheath

: the insulating covering that surrounds an axon with multiple spiral layers of myelin, that is discontinuous at the nodes of Ranvier, and that increases the speed at which a nerve impulse can travel along an axon

called also medullary sheath

More from Merriam-Webster on myelin sheath

Britannica.com: Encyclopedia article about myelin sheath

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