UMass Amherst KIN 460 - Regeneration in adult nervous system Handout (7 pages)

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Regeneration in adult nervous system Handout



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Regeneration in adult nervous system Handout

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Pages:
7
School:
University of Massachusetts Amherst
Course:
Kin 460 - Motor Control
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An ancient Egyptian papyrus acknowledges the difficulties of repairing brain and spinal cord damage Questions What types of nervous system regeneration exist When you examine a man with a dislocation of a vertebra of his neck and you find him unable to move his arms and his legs Then you have to say a disease one cannot treat How do PNS neurons regenerate How do CNS neurons regenerate What are features of spinal cord damage What are features of a stroke in the brain Question 1 Three types of nervous system repair or regeneration Part 1 I regrowth of axons Mainly PNS Growth cone change in speed and shape Cell adhesion molecules CAMS 1 Question 1 Three types of nervous system repair or regeneration Part 2 II restoration of damaged nerve cells in CNS glial cell proliferation Axons dendrites degenerate Some connections established glial cells form scar tissue Question 2 Question 1 Three types of nervous system repair or regeneration Part 3 III genesis of new neurons Shown in olfactory bulb and hippocampus not the cortex Question 2 Henry Head s peripheral nerve regeneration experiment On April 25 1903 the radial ramus cutaneous radialis and external cutaneous nerves were divided cut in the neighborhood of my elbow and after small portions had been excised the ends were united with silk sutures Before the operation the sensory condition of the arm and back of the hand had been minutely examined and the distances at which two points of the compass could be discriminated had been everywhere measured Ch 25 page 638 v Head Rivers and Sherren 1905 Brain 28 99 115 Recovery 1 General sense of touch pressure not localized 6 wks 2 Temperature 2 point discrimination light touch 2 years but less restoration 2 Question 2 Regeneration in peripheral nerves Question 2 Molecular and cellular responses that promote peripheral nerve regeneration Schwann Cells promote axon growth and synapse formation Peripheral nerve sheaths and Schwann cells facilitate growth of damaged axons Peripheral nerve back leg Regeneration of synapses Visual system Neuromuscular junction 3 Reinnveration of muscles following peripheral motor nerve damage Part 1 Reinnveration of muscles following peripheral motor nerve damage Part 2 Original synaptic sides remain intact for weeks Schwann cells Ach receptors Question 3 Question 3 The reaction of the three major classes of CNS glia to local tissue damage Damage to CNS Trauma Hypoxia stroke cardiac arrest Neurodegenerative disease All these lead to programmed cell death apoptosis Autoimmune system regulated glial cells macrophages contribute to degeneration and regeneration Brain myelin produced by oligodendrocites inhibits axon regrowth 4 Question 3 Cellular response to injury in the central nervous system Question 4 spinal cord damage Spinal Cord Spinal cord retraining based on current knowledge of central pattern generators Injecting L Dopa in spinal cord alternating flexion extension movements cat mouse 5 Spinal cord damage Plegia motor inhibition caudal to level of injury Quadriplegia all 4 extremities Paraplegia legs Hemiplegia one side stroke Symptoms Flaccid total loss of muscle activity Spastic increase in muscle tone Spinal cord damage Spinal cord injury Large sympathetic stimulation minutes Swelling loss of blood pressure restricted blood flow Ischaemia and activation of nerves Spinal cord shock weeks even undamaged areas become disabled release toxic chemicals 2nd cascade Inflammatory immune response causes more damage use methylprednisolone steroids Spasticity and hyperreflexia Question 5 Stroke Damages both lower innervate muscle fibers and upper motor neurons originate in brainstem and motor cortex Stroke damage to brain cortex Thrombotic blood flow reduction due to atherosclerosis 50 Embolic blockage due to embolus small object in bloodstream 30 Hemorrhagic rupture of cerebral blood vessel 20 http www sciencedaily com videos 2008 1207retrain your brain after stroke htm Pharmacological strategies to minimize neuronal injury after stroke due to inflammation Example excitoxicity glutamate acummulates in synapse excessive stimulation of glutamate receptors excites neurons to death 6 Spasticity and muscle tone Muscle tone resting level of tension in muscle Tone depends on Resting level of alpha motor neurons and Ia spindle afferents Structural aspects contractures Questions What types of nervous system regeneration exist How do PNS neurons regenerate How do CNS neurons regenerate Spasticity Increased tone Hyperactive reflexes Clonus rhythmic contractions due to stretching and unloading of spindle What are features of spinal cord damage What are features of a stroke in the brain 7


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