Nerves and nerve damage Flashcards
Describe the Seddon’s classification scheme of nerve and define the three terms.
Seddon is responsible for classifying peripheral nerve injuries into neuropraxia, axonotmesis, and neurotmesis.
Neuropraxia = the least severe, axons are whole but are damaged, reduced conduction speed, numbness, tingling.
Axonotmesis = moderately severe, damage or severance to some axons, support structures remain intact, regrowth possible.
Neurotmesis = Severe severance of nerve, sharp trauma, support cells gone, regrowth very unlikely, healing can sprout in any direction.
List the main causes of age-related deterioration of nerve cells/nerves.
Central = neuronal atrophy, loss of myelination and dopamine, connections not maintained as well.
Peripheral = declined axonal transport, impaired regeneration.
Outline what ischemic damage to nerves means.
Cells die releasing lots of neurotransmitters (depolarisation), massive calcium influx, damaged area of brain will lack oxygen because of the loss of neurons.
Briefly outline the function of SNARE proteins and highlight the importance of toxins such as botulinum and tetanus.
Calcium ions activate the snare complex which drag vesicles to fuse with postsynaptic membrane.
Botulinum toxin interferes with snare complex and is very poisonous, but can be used clinically to relax muscles.
Tetanus toxin cause infection and over activation of muscle groups.
