day 4 neural transduction

  1. concentration gradient
    element is in high concentration in one place, it tends to move to an area of lower concentration
  2. electrostatic pressure
    when charge of one kind accumulates in one place it tends to move away to an area of different charge
  3. Sodium potassium pump
    -helps maintain charge

    -pushes 3 NA+ out, 2 K+ in
  4. 3 main contributers of neural transmission
    - Alan Lloyd Hodgkin

    - Andrew Huxley

    -John Eccles
  5. When a neuron becomes active it releases....
  6. Neurotransmitters interact with...
    receptors, that ultimately cause closed ion channels to open and permit flow of ions
  7. when channels open up and permit + ions to flow into the cell, cell becomes....
  8. when channels open and permit - ions to flow into the cell becomes....
  9. EPSP, Excitatory post-synaptic potential
    it is depolarization of the neuron

    -Na flows in
  10. IPSP, inhibitory post-synaptic potential
    hyperpolarization of the neuron

    -Cl flows out
  11. brief description of post-synaptic potentials
    -begins at dendrites or cell bodies

    • -moves passively along dendrites and cell body
    • *moves rapidly

    -magnitude of signal diminishes with distance
  12. (PSP) info
    -many EPSP and IPSP in the post-synaptic neuron all the time

    -how these PSPs interact ultimately determines whether that cell will fire an a
  13. How these PSPs interact ultimately determines whether that cell will fire...
    an action potential
  14. spatial summation
     occurs when excitatory potentials from many different presynaptic neurons cause the postsynaptic neuron to reach its threshold and fire.

    ex) many shovels fill up a hole all at once
  15. Temporal summation
    occurs when a single presynaptic neuron fires many times in succession, causing the postsynaptic neuron to reach its threshold and fire.

    ex) one shovel trying to fill a hole
  16. summation
    a single neuron may receive tens to hundreds of synaptic contacts
  17. importance of position of summation
    PSPs generated distal portions of dendrites will impact less than PSPs generated proximal (close) to cell body.

    -PSPs diminish with distance
  18. Summation of ESPSPs and IPSPs sometimes leads to the generation of
    action potential
  19. IF cell is depolarized past a certiain value then...
    an action potential will be generated

    -value closer to zero
  20. description of action potential
    -all or none response

    -action potential triggered by crossing of threshold is same size every time one is triggered.
  21. Ion channels that are always open and sodium potassium pump are critical for...
    establishing the resting membrane potential of the cell (-70)
  22. Ligand-gated
    ion channels that open in response to neurotransmitters

    -these are critical for generating EPSP and IPSPs
  23. Voltage-gated ion channels
    some ion channels will only open when neurons membrane potential has reached a certain value

    -essential for generating action people
  24. when enough PSPs have summated to bring membrane to potential to threshold
    -voltage-gated sodium channels open
  25. when voltage-gated na+ channels open...
    Na+ floods into the cell because Na+ therefore has huge electrostatic pressure to move into the cell.
  26. Another reason When voltage-gated Na+ channels open...
    Na+ moves into the cell because pf its concetration gradient
  27. As Na+ moves into the cell, the membrane potential....
    • depolarizes further
    • *goes near positive
  28. when voltage-gated K+ channels open...
    -Na+ still flows into the cell via their channels

    but K+ flows out of the cell as well

    -K moves out because of its concentration gradient and eletrcostaci pressure`
  29. Summary of action potential
    • 1. PSPs bring membrane to threshold
    • 2. Na+ gates flood open
    • 3. As Na+ floods in, membrane depolarizes
    • 4. As membrane potential rises, voltage gated potassium channels open
    • 5.At 50+, Na gates shut off(this point neuron is positive reltive to the outside of cell-causes K to come out more because of gradients)
    • 6. As membrane potental begins to fall, K channels slowly begin to close
  30. 3 stages of action potential
    rising phase


  31. (stages) Rising phse
    Na floods into the cell
  32. (stages) Repolarization
    Na closes and K comes out
  33. (Stages) Hyperpolarization
    -K channels slow to close

    • - sodium potassium pump going to work to bring K back in
    • *3 Na out and 2 K in
Card Set
day 4 neural transduction
neural transduction