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94 Cards in this Set
- Front
- Back
basic elements of CNS
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spinal cord: contains tracts
brain stem: above the spinal cord, tracts go, location for most cranial nerve nculei cerebellum: coordination of movement cerebrum: gyri, and sulci, lateral, interhemispheric, and parietal occipital fissure basal ganglia: basal ganglia thalamus: sensory information synapses wher it readches the cerebral cortex ventricles: fluid filled sections, contain CSF |
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brain and intelligence
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there is no correlation between the brain and intelligence
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CNS cytology general
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10^12 neurons exist in the brain,
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glia
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glia outnumber neurons 10 to 1 and comprise 2/3 of nervous system
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glial cells are grouped into
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3 categories:
astrocytes oligodendrocytes microglial cells |
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astrocytes
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-processes of these cells contact the surface of capillaries and probably influence membrane permeability
-appear to remove or degrade neurotransmitters, and regulate K+ ion concentrations |
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oligodendrocytes
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-cells are responsible for myelination of axons in the CNS
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microglial cells
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cells are smaller than other glial cells and exhibit phagocytic activity, respond to infection
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ependymal cells
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line ventricles of the CNS
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neurons
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size: vary in size, can be pseudounipolar-or fusiform bipolar cells, dendrites increase surface area of an axon
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ganglia
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group of cell bodies outside CNS
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nuclei
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group of cell bodies in the CNS
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axon myelination
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some axons are heavily myelinated, others are unmyelinated, some are thick some are thin
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tracts
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axons grouped together and projecting from one site to another in the CNS are referred to as tracts
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neurotransmitters
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excitatory, inhibitory
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types of synaptic contacts
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axosomatic, axodendritic, axoaxonic, dendrodendritic, somatosomatic
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dendritic spines are often a site for...
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synpases!
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synapses/spines are dynamic
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they can be remodeled during learning
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microglia are thought to play a role in
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removal of plaques
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astrocytes
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synaptogenesis
lactate delivery K+ update (function in epilepsy?) Ca2+ signals and waves Release of transmitters ATP and adenosine Moderate sleep pressure -Can form glial scars -Can result in changes in vascular status, increase in blood flow in response to Ca2+ |
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spinal cord
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31-33 segments of human spinal cord, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1-3 coccygeal
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conus medullaris
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L1-L2
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spinal nerves and vertebrae
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1st cervical nerve exits above the atlas
8 th cervical exits between C7 and T1 all spinal nerves below C8, exit beneath their corresponding vetebrae |
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spinal cord
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composesd of white matter surrounding a core fo gray matter, long ascending tracts are composed of processes or axons
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white matter is divided into
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dorsal, ventral, and lateral funicili
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gray matter in spinal cord consists of
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secondary sensory neurons, interneurons and motor neurons
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the brain mainly consists of
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... interneurons ---- :)
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substantia gelatinosa
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appears to be involved in transmission of pain
-involved at all levels of spinal cord |
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clarke's nucleus
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transformation of information to the cerebellum
T1-L2/3: |
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intermediolateral cell column
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-T1-L2/L3, preganglionic sympathetic neurons
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sacral sympathetic plexus
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S2-S4, preganglionic parasympathetics to pelvic viscera
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acessory nucleus
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trapezius and SCM, extends from medulla to C5
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phrenic nucleus
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C3-C5 levels
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somatosensory pathways
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happen through sequence of 3 neurons, primary cell body is outside CNS in dorsal root ganglion (DRG, cells are primary neurons for ascending pathways, located as the same side, the receptors are supposed to convey)
-second order neuron varies for each pathways -third order neuron: resides within the thalamus and project to somatosensory area of the cerebral cortex |
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information that is not conscious
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does not reach cerebral cortex, but to projects to other regions of neuroaxis
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pyramidal system
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corticospinal tract travels through that
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extrapyramidal system consists of
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rubrospinal
tectospinal vestibulospinal rectospinal tracts |
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corticospinal tract
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origin: from cell bodies in cortex and traverse before reaching spinal cord, long descending motor fibers are positioned in the lateral white funiculus, synapses occur within the grey matter of the spinal cord,
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cspinal tract function
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to provide voluntary cortical drive to spinal motor systems to induce conscious movement
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cspinal course through spinal cord
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85-90% are ipsilateral to the motor neurons, fibers in the lateral corticospinal tract originate from contralateral cerebral cortex
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lesion in mortor cortex or cspinal tract
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is an upper motor lesion!
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upper motor lesions are characterized by
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spastic paralysis
clonus increased muscle stretch reflexes Babinski's sign clasp knife response lack of muscle atrophy (movements of the fingers are most commonly affected) |
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paresis
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voluntary muscle weakness
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plegia
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complete loss of motor control
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lower motor neuron lesion
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results in decreases in muscle stretch reflexes, flaccid paralysis, atrophy, fibrillations and fasiculations
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anterior corticospinal tract
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85-90% of descending fibers decussate in the meduallary pyramids, uncrossed 10%, may be involved in control of neck and shoulder movements
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other descending pathways that influence motor function
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rubrospinal: red nucleus (midbrain)
vestibulospinal: (medulla) reticulospinal (pons and medulla) tectopsinal (superiocolliculi) midbrain |
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rubrospinal
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red nucleus (midbrain), excites motor neurons, contralateral to origin, crossing occurs in midbrain, lateral funiculus of cord
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vestibulospinal
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ipsilateral to origin, travels in anterior region of lateral funiculus and anterior funiculus, mediation of postural adjustments
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reticulospinal
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majority are ipsilateral, travels in anterior region of lateral funiculus, voluntary movements
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tectospinal
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contralateral to origin, travels in anterior funiculus, iin response to movements to visual and auditory stimuli
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complete transection of the spinal cord
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C3 or above: respiration stops
C3,4,5, phrenic, spinal shock, flaccid paralyssis, with time, replaced with increased deep tendon reflexes, spasticity, appearance of babinski sign |
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partial transection
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some ascending and descending pathways are affected while others are spared
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brown sequard syndrome
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hemisection, paralysis and loss of tactile discrimination are tested on side of elsion, and pain and temperature lost on other side
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syringomyelia
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cavitation, suspended sensory loss, can get lower motor neuron than upper neuron
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compression of the cord from without
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tumor that may compress the long tracts or disk herniation that may impinge on the spinal roots
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neurosyphillis
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dorsal column disease
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amyotrophic lateral sclerosis
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degeneration of motor neurons, including ventral horn cells fo the spinal cord, corticospinal and corticobulbar tracts
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combined systems disease
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B12 neuropahty: bilateral degeneration of the dorsal and lateral funicului, resulting in damage to the dorsal column and corticospinal pathways, also spinocerebellar pathways
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multiple sclerosis
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demyelination of various regions of spinal cord
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focal spinal cord disease is characterid by an...
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upper level to the deficit, pin level, all function above is normal, below isn't
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sphincteric dysfunction
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often abnromal in spinal cord disease
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corticospinal tract is only found in the
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CNS. Upper motor neuron eweakness must come from a CNS lesion
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spinothalamic tract crosses in the
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spinal cord, whereas the posterior fibers don't cross unitl the medulla
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long tracts are laminated
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see stick and figure model!
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spinal cord imaging
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MRI is the best choice for visualization, can choose CT with myelogram
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Brown Sequard syndrome
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one half of spinal cord, loss of pain and temp contralateral, and vibration and sense ipsilateral, not that spinothalamic fibers may go up higher before crossing,
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syringomyelia
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a cavity, suspended suspensory loss, most common location is cervical pain upper extreimities, reactive astrocytes, shunting of the fluid may or may not help
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compression of the spinal cord from without
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osteophytes, intervetebral disc herniations, extrameduallary pain due to root, early involement of sacral segements ( spinothalamic and corticospinal tracts,
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subacute degeneration of spina lcord
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B12, damage to lateral corticospinal tracts, dorsal columns, upper motor neuron weakness and loss of position and vibratory and position sense, positive romberg's sign
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ALS
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both upper and lower motor neuron are invovled, mix of upper and lower motor neuron weakness, insidious in onset, fasciulations, bulbar ALS
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wallerian degeneration
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sectioning of peripheral nerve, central chromatolysis, sprouting at the proximal end begins immediately
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segmental demyelination
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myelin sheath disintegrates, undergo proliferation and remyelination usually occurs, nerve conduction may be permanently slowed through the area, of abnormal myelin
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distal axon degeneration
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dying back neuropathy (presumed that diseases of this type result from abnormalities of metabolic machinery, stocking and glove neuropathies (may show central chromatolysis)
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distal symmetric slowly progressive
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dying back, distal axon degeneration, metabolixc and toxic causes, axonal degeneration!
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acute fulminant predominatly motor neuropathy
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segmental demyleination diptheria and Guillan barre syndrome
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proximal, asymmetric, predominantly motor neuropathy
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single nerve, diabetes, amylodoisis, polyarteries nodosa, wallerian degeneartion of nerve trunks, individual fasicles
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chronic recurrent, hypertrophic neuritis
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distal motor and sensory neuropathy with a glove and stocking distribution, onion bulbs (repeated segmental demyelination)
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guillan barre syndrome
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autoimmune disease 7-10 days post a GI or respiratory infection
albumino cytologic dissociation, elevated protein with normal cell count, delayed hypersensitivity |
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spinal cord injury
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damage a series of events tha increases the extent of damage, overstimulation of free radicals, causing excitotoxicity, NFG, BDNF, NT-3, deprived of growth factors
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experimental strategies for spinal cord
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contusion, MRI, drugs that inhibit apoptosis, glial scar and inhibitory properties of myelin, glail scar and inhibitory properties of myelin cause a problem
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blocking myelin inhibitory molecules
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promotes growth
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neural growth factors
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can inject to promote growth, can also use nanotubes
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MAG protein
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inhibitory for neuron outgrowth
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GTPase roho, and rho inhibitors
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investigated to reduce the response to regenerating axons
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intrinsic capacity for re-growth
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peripheral nerves have a good capacity for re-growth
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stem cells
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can use them to grow,
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NOGO
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receptor that shows that blocking allows for growth
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nicotinic NMJ
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striated muscle, presynaptic region (VGCC,),
Post synaptic: nAChr |
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physiology of acetylcholine release at the NMJ
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depolarizing axon nerve action potential goes down opens up Calcium channel,
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Myasthenia gravis
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IgG against naChr, epidemiology, 2-10, per 100,000, 10% associated with thymoma
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clinical features of myasthenia gravis
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muscle weakness, MG, ptosis, double vision, difficulty swallowing, slurring of speech, shortness of breath
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diagnosis of MG
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tensilon test, nAchR antibodies, tensilon is a short acting acetylcholinesterase inhibitor
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treatment of MG
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symptoms: pyridosgostimine, autoimmune treatments: prednisone, azathriopoine, cyclosporine, mycophenlate, plasmaphoresis, IVig, thymectomy
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