Neuro Phys test 1

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Neuro Phys test 1
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2011-08-08 13:17:56
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UWS Neuro Phys
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test 1
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  1. Cajals Principles
    (5)
    • 1. The neuron is the elementary signaling unit
    • 2. Neuron has dynamic polarization ->allows circutry flow
    • 3. Defined the synapse (area of connection)
    • 4. Connection specificity (only connect to one part)
    • 5. Synaptic Plasticity - the connections in the brain can be modified by experience
  2. Main signal recording
    • Recorded by cathode ray oscilloscope
    • microelectrodes and macroelect.
  3. EEG
    • 1st recorded with macroelectrodes (brain mapping) = receptotopic mapping
    • - shows abnormalities but cant tell what is wrong
  4. Peripheral Nerve Recordings
    alpha, beta, gama = mylenated (faster and thicker)

    c = unmylenated = slower/thinner
  5. Nerve recruitment
    Large(fast) to small (slower)
  6. Electrical recordings
    • Excellent with time
    • bad with location
  7. Type and tissue: EEG
    Cortex
  8. Type and tissue: ERP/SEP
    Sensory Motor Pathway
  9. Type and tissue: Whole nerve potential
    peripheral Nerve
  10. Type and tissue: EMG
    Skeletal Muscle
  11. Fast electrical membrane communication
    • only plasma membrane involved
    • - direct and indirect STP's
    • -STP's are ATP dependent
    • -Nerve voltages are either Graded or all or none
  12. Graded Potentials
    • Passive - Ligand gated
    • - occur in dendrite and soma
  13. All or None
    • Active regenerative propogation - voltage gated
    • - occur at AH-IS, axon, axon terminal
  14. Neuron electrophysiological techn.
    (where to put the clamps)
    • 1. extracellular
    • 2. intracellular
    • 3. Patch clamp recordings
  15. Patch Clamp recording
    • -Recording ion channels
    • -post synaptic membrane
    • -in vitro
  16. Sherrington Discovered
    • - synaptic delay
    • - spinal reflexes
    • - excitatory/inhibitory responses

    soup/chemical vs sparks/electrical debate
  17. Membrane electrophysiology
    membrane is permeable to lipids but not to cation/anions
  18. cations and anions can cross membrane by:
    • 1. slow - transport membrane protiens
    • 2. rapid - ion channels*
  19. Ion channels
    • Passive - leakage
    • Active - graded, all or none, neurosecretion
  20. passive ion channels
    • Leakage
    • - always open
    • - responsible for RMP
    • - single ion selective *
  21. Active ion channels
    • Graded/ all or none/ neurosecretion
    • - opened or closed (by voltage.ligands, sensory stimuli
    • - have both single and multiple ion selectivities
  22. Ion distribution
    Na, Cl,Ca - more outside

    k - more inside

    Actively distributed
  23. Equilibrium Potential
    • na +60
    • k -90
    • cl -70
    • ca +246
  24. actively distributed Na K pump
    • ATP needed
    • - 3 Na out
    • -2 K in
  25. Diffusional force
    concentration across a barrier
  26. Electrochemical force
    like ionic charges repel, unlike attract
  27. Intracellular membrane voltage
    • set closest to the E ion of the most permeable ion
    • RMP is -70 due to K
  28. RMP #'s
    • same for one cell but varies from cell to cell
    • small neurons = -55
    • muscle =-80
    • glial = -90
  29. Glial cells RMP
    purels based on K+ diffusion, doesnt generate electrical signals
  30. RMP in neurons and Muscle cells
    • Predominantely K+ leaking out
    • some Na+ leakage in

    Ca and Cl dont contribute to RMP
  31. Leak ion channels
    • -Always open
    • -single ion specific
    • -placed all throughout the entire cell/neuron
    • - more channels for K>Cl>Na
    • - produce the "bacground" against all other electrical signals
  32. Ligand-gated Channels
    :STP's
    • Graded Synaptic potentials - EPSP / IPSP
    • Ionotropic (direct /fast)
    • metabotrophic (indirect/ slow)
  33. Location and Event: Dendrites and Body/soma
    graded synaptic events

    TRANSDUCTION
  34. Location and Event: A.H. and TZ
    AP generation

    TRANSFORMATION
  35. Location and Event: Axon
    Impulse conduction

    PROPAGATION
  36. Location and Event: Axon terminal
    neurosecretion

    TRANSLATION
  37. Temporal summation
    same cell fires 2x in a row
  38. Spatial summation
    2 cells fire at the same time
  39. Sutherland discovered
    ionotrophic and metabotrophic STPs
  40. Ionotrophic STP
    • direct/ fast
    • - rapid/reversible
    • - newer
    • - due to direct selective ligand binding
    • - can open/close ion channels
  41. Metabotrophic STP
    • slow, gated ion channels
    • - cascade needs to occur
    • - many target substrates
    • - old
  42. conductance
    • increased G = gate opening
    • decreaded G = gate closing
  43. Post synaptic membrane EPSP
    • CAMs - neurexins and neurligands **
    • ionotrophic STP - middle of the synapse
    • metabotrophic stp - outside, surround iono
  44. passive electronic decay
    as the epsp/ipsp travels through the cell body to AH it will degrade, if it doesnt reach threshold by AH then no AP
  45. IPSP
    • hyperpolarization = increase negativity
    • graded- temporal vs spatial summation
    • both ionotrophic and metabotrophic
  46. Post synaptic membrane - IPSP
    • CAMs - neurexins and neurligands
    • ionotrophic STP -> gaba A*
    • metabotrophic STP -> gaba b*
    • also have passive decay

    ionotrophic receptors are still in the middle of metabotrophic, but there are two rings of receptors
  47. TRIGGER ZONE
    aka Axon hillock
  48. Eccles Discovered
    the winner takes all idea, integration of epsp and ipsp
  49. Inhibitory AA
    90% gaba
  50. Excitatory AA
    • 75% glutamate
    • 25% other NT (ACH, NA,serotonin)
  51. Hodgkin - Huxely model
    sodium potasium duct* - timed sequence of 2 different ion selective channels

    • 1. Na triggers depolarizating phase- into cell
    • 2. K repolarize membrane back to RMP - moving out of cell

    these are measured by patch clamp
  52. NA/K channels
    • have:
    • - ion selectivity
    • - voltage sensitive/ regenerative/ able to propogate
    • - have a refractory/inactive period, cant summate spikes
    • - can be blocked by toxins
  53. Absolute refactiveness
    • inactivation of voltage gated channels
    • - after S1, s2 fails to form an A.P.
    • - all Na and K channels are closed
  54. Relative refractiveness
    • -When s2 fails to elicit a normal sized impulse
    • - some channels opened, but not all
  55. Sodium and Potassium voltage channels (NaV) (Kv)
    • specifically located-
    • -at AH
    • -entire length of unmylenated axon
    • - nodes of ranvier
    • -pre synaptic terminal membrane of myelinated
    • -sarcolemma
    • -t-tubule
  56. LCC
    Local cation current - caused by Na influx, depolarizes

    • - speed of propogation depends on fiber type
    • increase axon size = decre resistance = faster
    • small =unmylenated
  57. Large Myelinated Axons
    • use Saltatory conduction
    • impulses are regenerated at nodes of ranvier
  58. Neuron
    • fastest 0.5 ms
    • na in k out
  59. skeletal muscle
    • 4 ms, slowest
    • na in k out
  60. cardiac muscle
    • 4 ms, slowest
    • na and ca in, k out *
  61. visceral smooth muscle
    • 1 ms, 2nd fastest
    • ca in k out *
  62. Neurosecretion
    • single impulse causes release of small neurotransmitters
    • -glu, gaba, ach

    LCC travels to azon terminal, opens Ca voltage gated channel, the ca triggers STP to release NT's
  63. quantal hypothesis
    single impulses force small vesicles to release contents into synaptic cleft -> bind with ligand gated ion channels
  64. Repolarizing and reuptake
    stop the release of ca and stop the release of NT
  65. 3 types of voltage gated channels
    • 1. NA
    • 2. K
    • 3. Ca
  66. 1 quanta
    1 batch of NT raise by 1 mv
  67. quanta release dependent on:
    ca concentration, more = more release
  68. Dale's rule
    a single neuron releases same chemical signals at all of its synaptic terminals
  69. Presynaptic inhibiton and facilitation
    • aka neuromodulation
    • - inhibit = decrease NT release
    • - facilitation = increase release
  70. Excitatory Synapses
    • Grey type 1
    • EAA = glu
    • wide synaptic cleft
    • fast or slow
  71. Inhibitory synapses
    • Grey type 2
    • IAA - gaba
    • narrow synaptic cleft
  72. Ionotrophic EPSP
    • Ampa R
    • increase G
    • NA flows in
    • depolarization
  73. Metabotrophic EPSP
    • mGlu-R
    • neuropeptide transmitter
    • decrease G
    • k stays in
    • depolarization
  74. Ionotrophic IPSP
    • Gaba -a
    • increase G
    • increase Cl in
    • hyperpolarization
  75. Metabotrophic IPSP
    • gaba - b
    • increase G
    • increase K out
    • hyperpolarization
  76. All or none LAW
    • - triggered at a standard threshold voltage
    • - have a standard magnitude
    • - standard duration
    • -standard voltage waveform
    • -conduct or propagate at a constant speed
    • -electrogenic- ability to self regenerate

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