Lecture 14: Peripheral Nerve

  1. PNS
    • Somatic- motor & sensory
    • Autonomic- S,P, eneteric
  2. Dendrites
    • motor & atonomic have
    • sensory- pseudounipolar
    • protein synth machinery
  3. Axons
    • lack protein synthesis, must use fast azonal transport to transport things along MT
    • MT & mitochondrai (DEVOID of large granules)
  4. Mylenating Schwannc cell
    • Recruited by >=1 micrometer diameter axons
    • Neuregulin-determines amt of mylentation
  5. Nonmylenating cells
    • <=1 micrometer diameter axons
    • Gathers bundle of axons
  6. Satellite cell
    • around cell body & proximal dendrites
    • Barrier to enter cell body
  7. Perineurium
    BBB- tight junctions
  8. Endonerium
    • also BBB in capillaries- tight junctions
    • Schwann cell (more abundant than fibroblasts)--> synthesize collagen
  9. Nodes of Ranvier
    • high Na and K channels
    • Devoid of myelin
    • Where collateral axon branches come off
    • In PNS-> reduced diamerter at nodes
  10. Schmitt-Lantermann Clefts
    Periodic spaced Schwann cell
  11. Dorsal root ganglion
    • heterogenous in size and function
    • Largest: touch-sensitive, myelinated axons
    • Smaller- pain fibers, unmyelinated
  12. Sensory neurons
    • Pacinian corpuscle: sensitive to touch, a single axon surrounded with myelin by modified Schwann cell until reaches corpuscle- surrounded by CT and fluid
    • Non-encapsulated (free) endings: not surrounded by CT sensitive to pain.
  13. Motor Neurons (efferents)
    • Alpha motor neurons- largest, longest, mylenated
    • Gamma motor neurons- small, unmyelinated (<1 um)
  14. Autononmic NS
    • S:
    • "forf"
    • dependent on Nerve Growth Factor (NGF)
    • P: fine tune and maintain norma function
    • E: receive input from S&P but autonomous, reg gut, AUerbach's and Meissner's plexus, enetic glial cells
  15. Lenghts of ganglia in S&P
    • S: pre->short post->long
    • P: pre->long post->short (ganglia close/on target)
Card Set
Lecture 14: Peripheral Nerve
mylenation, nerves, cell bodies, axons