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Neuromuscular junction

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Neuromuscular junction

  1. 1. NEUROMUSCULAR JUNCTION Presented by: VARNAKA C H 1ST BNYS
  2. 2. INDEX • • • • • • • • Definition Structure Neuromuscular transmission Neuromuscular blockers Neuromuscular stimulators Motor unit Applied physiology Questions from previous exams
  3. 3. • Definition Junction between terminal branch of nerve fiber and muscle fiber
  4. 4. Structure
  5. 5. • Axon terminal- terminal branch of nerve fiber • Motor end plate- bulb like expansion of axon terminal • Synaptic trough/ gutter- depression on the muscle fiber due to invagination of motor end plate • Subneural cleft- numerous folds of post synaptic membrane
  6. 6. • Presynaptic membrane- membrane of nerve ending • Postsynaptic membrane- membrane of muscle fiver • Synaptic cleft- space between post and presynaptic membrane • Basal lamina- thin spongy layer of reticular matrix in synaptic cleft
  7. 7. Neuromuscular transmission • Transfer of information from motor nerve ending to the muscle fiber through neuromuscular junction to initiate muscle contraction
  8. 8. Series of events 1. 2. 3. 4. Release of acetly choline Action of acetly choline Development of end plate potential Development of miniature end plate potential 5. Destruction of acetyl choline
  9. 9. Release of acetly choline
  10. 10. Action of acetly choline
  11. 11. Development of end plate potential
  12. 12. Devolpment of miniature end plate potential
  13. 13. Destruction of acetyl choline
  14. 14. Neuromuscular blockers Drugs which prevent transmission of impulse across neuromuscular junction significance..? useful in surgical and trauma care
  15. 15. • Curare blocks ach receptors by binding • Bungarotoxin - (snake venom extract) blocks ach receptors • Botulinum toxin - (clostridium botulinum) prevents realease of ach from axon terminal
  16. 16. Neuromuscular stimulators Inactivate Ach esterase Drugs stimulating neuromuscular transmission •Significance…..? Treating weak or paralyzed muscles Repeated stimulation from Ach Continuous contraction of muscle fiber
  17. 17. Motor unit • Motor neuron, axon terminal and muscle fibers together called as motor unit
  18. 18. • Muscles involved in fine movements- less muscle fibers in motor unit ex: movement of eyes- ocular muscles • Muscles involved in coarse movements- more muscle fibers in motor unit ex: flexion – leg muscles
  19. 19. Recruitment of motor units • Process by which more and more motor units are put into action • Force of contraction increases
  20. 20. Applied physiology 1. Myasthenia gravis - autoimmune disorder - antibodies for Ach receptors
  21. 21. 1. Eaton lambert syndrome - autoimmune disorder of NMJ - antibodies- calcium channels in axon terminal
  22. 22. Question of previous year • Neuromuscular junction- (5m)- aug 2006 • Draw a neat diagram of neuromuscular junction. Describe the transmission of impulse across neuromuscular junction- (10m)- jan 2008

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