Regeneration of Nerve Fibers

Regeneration of Nerve Fibers - regenerating axons and...

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Regeneration of Nerve Fibers Damage to nervous tissue is serious because mature neurons do not divide. If the damage is severe or close to the cell body, the entire neuron may die. Other neurons normally stimulated by the damaged axon may die as well. In certain cases, cut or compressed axons in peripheral nerves can regenerate. Almost immediately after a peripheral axon has been severed or crushed, the separated ends seal off and then swell. Within a few minutes, the axon and its sheath distal to the site of injury, begin to disintegrate. This process spreads distally from the site of injury. Generally, the entire axon distal to the injury is degraded within a week. After removal of the debris, the surviving Schwann cells proliferate and migrate into the site of in jury forming cellular cords that guide the regenerating axon "sprouts" across the gap and attempt to make their original contacts. The Schwann cells protect, support, and remyelinate the
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Unformatted text preview: regenerating axons and release growth factors to encourage growth. Within two days of injury, the cell body swells, and its chromatophilic substance breaks apart and disperses within the cell. This signals that the neuron is preparing to synthesize proteins to support regeneration. Axons regenerate at the rate of 1 to 5 mm a day. The greater the distance to regenerate, the less chance of recovery because the axonal sprouts tend to escape into surrounding areas and form a tissue mass called a neuroma. Post-trauma axon regrowth is never exactly the same as what existed before injury. Much of the functional recovery involves retraining the nervous system to respond appropriately so that stimulus and response are coordinated. Fibers within the CNS never regenerate distances more than 1 mm under any circumstances. Damage to the brain or spinal cord are viewed as irreversible....
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This note was uploaded on 11/22/2011 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.

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