Agents 5

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  1. Duration to stimulate nerves
    200-400microsec (short)
  2. Duration needed to stimulate denervated muscles
    milliseconds (long) --> cant use battery pack
  3. used for non healing wounds
    • hi volt
    • Hi-volt best for non healing wounds
  4. Physiological response to electrical cunrrent
    • 1. Muscle contraction through nerve or muscle stimulation
    • 2. Stimulating sensory nerves to help in treating pain
    • 3. Creating an electrical field in tissue to stimulate or alter the healing process
  5. active transport mechanis
    • cell continually moves Na+ out and K+ in
    • --Produces an electrical gradient with + charges outside and - charges inside
  6. Nerve Depolarization
    • resting membrane potential must be reduced below threshold level
    • When stimulate axon AP goes in both directions (ortho and anti dromically)
    • Need a good enough intensity and duration: pulse charge (phase charge for monophasic) will reach threshold
    • Galvanic have short pulse duration (29 micro sec preset in duration) so increasing voltage with knob to reach threshold and pulse charge (duration already set)
    • -----Increase amplitude to get enough of a phase charge
  7. Orthodromic
    • normal direction of nerve flow (AP)
    • -- nerve free endings: distal to proximal
    • -- efferent nerve endings: prox to distal
  8. Antidromic
    the opposite direction nerve flow is normally propagated
  9. Depolarization Effects
    • As nerve impulse reaches effector organ or another nerve cell, impulse is transferred between the two at a motor end plate or a synapse
    • a transmitter substance is released from nerve
    • Transmitter substance causes the other excitable tissue to discharge causing a twitch muscle contraction
    • Muscle and nerve respond in an all-or-none fashion and there is no gradation of response Firing rate depends on type of alpha motor neuron
    • ----Slow twitch: 20 x sec
    • ----Fast twitch: 50 x sec
    • Every time there is a pulse the alpha motor neuron causes contraction: unlike in normal muscle contraction
    • ----can lead to fatigue bc firing too fast
  10. If 100pps for 1hr: fatigue
    • Ach-e overwhelmed bc too much Ach, cant get back into presynaptic vesicles and Ach-e runs out (fast frequency fatigue)
    • May be good for muscles in spasm bc spasm deplete of Ach bc in have enough Ach-e but ended up having worse spasm
  11. system 206
    long duration, low intensity
  12. Shape of AP curve
    relates intensity of electrical stimulus (strength) and length of time (duration) necessary to cause the tissue to depolarize
  13. Rheobase
    • minimum intensity of current necessary to cause tissue excitation when applied for a maximum duration
    • Electodiagnostic test to see how sick your nerves are
    • Machine set to long duration (milliseconds), and gradually increase amplitude until nerve contracts
    • Sick nerve: shifted up : will take more intensity at any duration
  14. Chronaxie
    • length of time (duration) required for a current of twice the intensity of the rheobase current to produce tissue excitation
    • Find rheobase and set time, slowing increase duration until AP stimulated
    • Increased with sick nerve
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Agents 5
2015-07-21 17:25:05

Agents 5
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