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14 December, 20:17

D. V., a 32-year-old man, is being admitted to the medical floor from the neurology clinic with symptomsof multiple sclerosis (MS). D. V. has experienced increasing urinary frequency and urgency over the past2 months. Because his female partner was treated for a sexually transmitted infection, D. V. underwenttreatment, but the symptoms did not resolve. D. V. has also recently had two brief episodes of eye "fuzziness" associated with diplopia and flashes of brightness. He has noticed ascending numbness and weakness of the right arm with the inability to hold objects over the past few days. Now he reports rapidly progressing weakness in his legs along with blurred, patchy vision.

Required:

MS is associated with scattered, patchy demyelinization of the central nervous system (CNS). What does myelin do? What is demyelinization?

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Answers (2)
  1. 14 December, 21:34
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    The myelin is the component of the myelin sheath which surrounds the entire length of the axon. it is made up of water, lipid and protein It is rapped in concentric fashion or rings along the length of axon, in a process called myelination or myelinization

    its major functions are to protect the axon, to maintain insulation, to speed up the rate of transmission of action potential through salutatory conduction along the nodes of Ranvier of an axon and ultimately to maintain the integrity of the action potential along the axon.

    When the myelin of the myelin sheath is damaged or degenerated (example in the axons of the brain and spinal cord) and replaced with hard patch layer demyelinization occurs. It affect the conducts and transmission of the action potentials and therefore results in loss of motor control as exemplified in the question.
  2. 14 December, 22:16
    0
    Myelin sheath:

    It is a multilayered lipid and protien covering produced by neuroglia (Schwann cells in PNS and Oligodendrocytes in CNS). It has following functions:

    It acts as an insulator thus restricting impulses within the single nerve fibres. Prevents the stimulation of neighbouring nerve fibers. Increase the speed of impulse conduction through the nerve fibres, the impulses jump from one node to another. It covers the axis cylinder from damaged and suppressed. It provides nutrients to axis cylinder.

    Demyelination:

    Demyelination is defined as the disruption of the myelin sheath. It ma occur in both CNS and ANS. It may be inherited or acquired.

    Demyelination occurs in:

    Autoimmune diseases Infectious diseases Toxins Metabolic processes Vascular process. Multiple sclerosis Encephalomyelitis
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