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EXAM 2
Principles of Electricity, Application/Set up of E-Stim
41
Anatomy
Undergraduate 2
03/18/2013

Additional Anatomy Flashcards

 


 

Cards

Term
electron
Definition
particles of matter possessing a negative electrical charge
Term
ampere (A)
Definition
rate at which electrical current is flowing
Term
polarity
Definition
positive and negative poles
Term
volt/voltage
Definition

1 volt = potential difference required to move 1 coulomb or charge

 

voltage: force resulting from an accumulation of electrons at 1 point in an electrical circuit

Term
conductor
Definition

materials that permit the free movement of electrons, minimal opposition to current flow

(metals, electrolyte solution)

Term
insulator
Definition

materials that resist current flow

(air, wood, rubber, glass)

Term
Ohm
Definition
measure of resistance
Term
electrical impedance
Definition
the opposition to electron flow in an insulator
Term
Ohm's Law
Definition

current flow (l) = voltage / resistance (R)

a current with high resistance will have less flow

Term
Watt
Definition

rate at which electrical power is being used, measurement of total electrical energy

watt = volts x amps

Term
direct current
Definition

(Monophasic)

uninterrupted unidirectional flow of electrons, can change the polarity

[image] 

Term
alternating current
Definition

(Biphasic)

uninterrupted bidirectional, constantly changing, reversing polarity; terminators of the generator/source change from positive to negative

[image]

Term
pulsatile current
Definition

interrupted for short periods of time with no electron flow, series of pulses of shor duration

  • Can be unidirectional or bidirecional
    • monophasic- similar to DC (unidirectional - either +/-) with periods of non current flow
    • biphasic- similar to AC (bidirectional- +/-) with periods of non current flow

[image]  <----monophasic

[image]<---- biphasic (symmetrical vs. asymmetrical)

Term
frequency
Definition
# of pulses per second
Term
waveform
Definition
graphic representation of shape, direction, amplitude, duration, and pulse frequency of current
Term
amplitude
Definition

intensity of the current (highest point of each phase)

AKA- peak amplitude

SAME AS VOLTAGE AND CURRENT INTENSITY

Term
pulse
Definition

individual waveform, isolated electrical event separated by a finite (off time) period of time from the next event

(contains one or more phase)

Term
phase
Definition

unidirectional=monophase=known polarity=one phase/pulse

 

bidirectional=biphasic=2 separate phases/cycle

Term
cycle
Definition

complete wave of an alternating current

(pulse applies to monophasic current)

Term
pulse duration
Definition

length if time current is flowing in one cycle, aka pulse width, beginning of the phase to the conclusion of the final phase (or time that each pulse lasts)

  • monophasic: pulse duration equals phase duration
  • biphasic: combined phase duration equals pulse duration
  • pulsatile: pulse duration is determined by the combined phase durations and interphase interval
    • sum of phases + interphase interval = pulse duration
Term
phase duration
Definition
time that each phase lasts
Term
cycle duration
Definition
same as pulse duration but for AC current only
Term
interphase interval
Definition
interruption betweeen individual phases (off time)
Term
interpulse interval
Definition
period of time between individual pulses, short period of time without current
Term
rate of rise
Definition
how quickly a waveform reaches its maximum amplitude
Term
rise time
Definition
time required for a  waveform to go from zero to peak amplitude
Term
decay time
Definition
time required from a waveform to go from peak amplitude to zero
Term
asymmetrical current
Definition

different shapes for each phase

  • balanced- the net charge in both directions is equal
  • unbalanced- one phase has a greater net charge

(AC only)

Term
Symmetrical
Definition

same shape and size for each phase in both directions

 

(AC only!)

Term
pulse charge
Definition

total amount of electricity being delivered to the patient during each pulse, total # of electrons within a pulse

  • monophasic current: pulse charge and phase charge are always the same and always > 0
  • biphasic: pulse charge is equal to the sum of the phase charges
    • if pulse is symmetric, net pulse charge = 0
    • if pulse is asymmetric, net pulse is >or< 0

 

Term
pulse period
Definition

elapsed time from the initiation of 1 pulse to the start of the subsequent pulse

 

(Pulse duration + interpulse interval)= pulse period

Term
modulation
Definition
alteration in the amplitude, duration, frequency of the current
Term
burst modulation
Definition

occurs when pulsatile or biphasic current flows for a short duration and then is stopped for a short time in a repetitive cycle

bursts: combined set of 3 or more pulses

Term
beat modulation
Definition

produced when 2 interfering biphasic current waveforms with differing frequencies are delivered to 2 separate pairs of electrodes through separate channels within the same generator

 

2 PAIRS OF ELECTRODES IN CRISSCROSSED PATTERN SO THE CIRCUITS INTERFERE WITH ONE ANOTHER

 

 

Term
ramping/surging modulation
Definition

current builds up gradually to maximum (preset) amplitude, used to elicit a muscle contraction, very comfortable type of current due to gradual increase in intensity of contraction

 

EX: russian

Term
current density
Definition

amount of current flow per cubic volume

  • must be high enough to cause depolarization
  • highest where electrodes meet the skin, decreases with skin penetration - difficult with fat layers
Term
monopolar electrode
Definition

electrodes of 2 different sizes

  • ACTIVE ELECTRODE: placed where the treatment effect occurs
  • DISPERSIVE ELECTRODE: completes the circuit; fastened to a body part at a distant location
    • dispersiive pad has much larger surface area with little or no stimulation/current density

COMBO!!

Term
bipolar electrode
Definition

2 electrodes of the same size

  • both electrodes from single channel are placed over the target area
  • both electrodes are same size (no dispersive pad) - should have equal stimulation at each electrode
  • current is limited to target tissue

PRE-MOD, RUSSIAN WITH TWO PADS

Term
Quadripolar electrode
Definition
  • each channel split into 2 electrodes, all 4 applied over target tissue
  • intersecting/interfering or parallel
    • intensity from each set of electrodes adds together in order to increase intensity
  • If superficial, pads should be closer together
  • placement farther apart = greater depth of penetration and less specificity
  • placed parallel with muscle fibers = greater conductivity
IFC
Term
constructive interference
Definition

combined amplitude of 2 distinct circuits increases the amplitude

(if both waves originate at the same time, they combine)

 

Term
destructive interference
Definition

combined amplitude of 2 distinct circuits decreases the amplitude

[if both waves are out of sync; one generator goes in one direction (positive) and the other goes in the opposite (negative) direction; the waves cancel out]

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