day 5- lecture

  1. EPSP: Excitatory post-synaptic potential
    depolarization of the neuron
  2. IPSP: inhibitory post-synaptic potential
    hyperpolarization of the neuron
  3. Where does summation take place?
    summation takes place at theĀ axon hillock
  4. 2 ways to reestablish the resting potential
    -when both voltage gated channels close, Na and K flow through the alwasy opened channels due to concentration gradient and electrostatic pressure

    -sodium potassium pump also goes at work
  5. During hyperpolarization period, the neuron is...
    refractory period
  6. Refractory period
    another action potential cannot be generated for time being
  7. 2 types of refractory periods
    -absolute refractory period and relative refractory period
  8. Absolute refractory period
    time period during which no additional action potential can be generated
  9. Relative refractory period
    the neuron is resistant to another action potential, but stronger EPSPs can still evoke an action potential

    *very strong situmli can evoke A.Ps
  10. Where is the action potential generated from?
    • axon hillock
    • *neighboring areas adjacnet to local changes will be influenced to to trigger the opening of voltage gated Na channels
    • **this is how it is moved across the lenght of the axon to axon terminals
  11. Action potential moves along the axon towards the terminal leaving behind...
    membrane that is refractory for a few milliseconds
  12. As action potential travels through myelinated axon, they
    • become passive and decrease in magnitude
    • *but they speed up
  13. Are there channels underneath the myelin?
  14. gaps on the myelinated axons
    nodes of ranvier
  15. nodes of ranvier
    voltaged-gated channels regenerate the action potential

    *travels much faster than unmyelinated
  16. Saltatory conduction
    • action potential is propagated in a manner called saltatory conduction.
    • *leap
  17. Motor neuron speed
    80-120 m/s
  18. how does Tetrodotoxin affect the generating of A.P?
    • -blocks Na+ channels
    • *thats how it is lethal
  19. How does information pass from one cell to the next?
    • Chemical transmission, Neurotransmitters
    • * they then act on the next cell to initiate either EPSP or IPSP and the cycle starts over
  20. What happens when action potentials reach axon terminals?
    they casue to release neurotransmitters
  21. Synaptic cleft
    • space between the axon terminal and the membrane of the next cell
    • *synapse
  22. Presynaptic membrane
    terminal that releases neurotransmitter
  23. Postsynaptic membrane
    membrane that receives the nuerotransmitter on the other side of the synaptic cleft
  24. Where are the neurotransmitters held?
    • vesicles
    • *spheres
  25. Nuerotransmitters come in two types
    large and small molecules
  26. Where are the small molecule neurotrasnmitters made?
    • -cytoplasm of axon terminal or buton.
    • *packaged by golgi complex on terminal

    -smaller than vesicles that contain larger neurotransmitters
  27. description of large molecuels of nuerotransmitters
    -peptides, small proteins

    -made in cytoplasm of the soma, packaged there by golgi complex into vesicles

    -then they are trasnported to the terminal along microtubules
  28. As A.P reaches terminals, voltage change opens anohter type of voltage gated channel...
    • voltage-gated calcium channels
    • *concentrated near the synapse
  29. Influx of Ca causes vesicles to move to...
    • presynaptic membrane
    • * w/o a.p no nuerotransmitter is released
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day 5- lecture