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634: Electrotherapy Modalities > Basic Principles of Electricity (Part 1) > Flashcards

Basic Principles of Electricity (Part 1) Flashcards

1
Q

What is an electric current?

A

A flow of charged particles. Electrons in metal and ions in the human body

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2
Q

What is capable of propelling the charged particles in an electric current from higher to lower energy levels?

A

Electrical force

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3
Q

Increased ions produces _____ potential electrical energy

A

increased

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4
Q

What does Q stand for?

A

electrical charge

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5
Q

What is charge measured in?

A

coulombs

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6
Q

3 fundamental concepts about electric charge

A

1) Like charges repel, opposite charges attract
2) Charge can be transferred
3) Charge cannot be created, nor destroyed

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7
Q

What are ions?

A

elements with either an excess or a deficiency of electrons

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8
Q

__ions are positively charged ions (Na+, K+) and __ions are negatively charges ions (Cl-)

A

cations

anions

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9
Q

What does polarity indicate?

A

relative charge

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10
Q

An ____ is a positively charged electrode whereas a ____ is a negatively charged electrode

A

anode

cathode

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11
Q

Anodes attract ____ ions whereas cathodes attract _____ ions

A

negative

positive

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12
Q

What does I stand for?

A

Current

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13
Q

Define current

A

The rate of flow of charged particles

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14
Q

What is current measured in?

A

amperes

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15
Q

What does current (I) equal?

A

Current (I) = Charge (Q) / Time (t)

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16
Q

Current travels from the __ode to the __ode

A

anode –> cathode

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17
Q

Define voltage

A

the force resulting from an accumulation of electrons at one point in an electrical circuit.

aka the intensity or strength of the current

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18
Q

What does Ohm’s Law state?

A

the current in an electrical circuit is directly proportional to the voltage and inversely proportional to the resistance

Current flow (I) = Voltage (V) / Resistance (R)

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19
Q

What do watts indicate?

A

The rate at which electrical power is being used

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20
Q

Resistance increases as the cross sectional area ____ and its length _____

A

decreases

increases

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21
Q

Materials that permit free movement are called what?

A

conductors

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22
Q

Materials that resist current flow are called what?

A

insulators

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23
Q

define conductance

A

the ease with which current flows along a conducing medium

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24
Q

Of the following which are good and which are poor at conducting?

Skin 
Fat 
Blood
Muscle 
Bone
Nerve
A
  • Skin is poor
  • Fat is poor
  • Blood is the best
  • Muscle is good
  • Bone is the poorest
  • Nerves are good
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25
Q

Tissues high in what are considered good biologic conductors?

A

water

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26
Q

What is capacitance?

A

The property that allows the system to store charge

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27
Q

What is impedance?

A

The opposition to alternating currents

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28
Q

Higher frequency of stimulation = _____ impedance of tissues

A

lower

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29
Q

What is an electrical circuit?

A

The path of current from a generating power source through various components back to the generating source

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30
Q

In a ____ circuit electrons are flowing, and in an ____ circuit the current flow ceases.

A

closed

open

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31
Q

What are the 2 patterns in which components that provide resistance to current flow may be connected to one another?

A
  • series

- parallel

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32
Q

What is the difference between an series and parallel circuit?

A

In a series circuit there is only one path for current to get from one terminal to another. In a parallel circuit, two or more routes exist for current to pass between the 2 terminals

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33
Q

How are the component resistors arranged in a series circuit?

A

end to end

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34
Q

In a series circuit the total resistance to current flow is equal to what?

A

The resistance of all of the components added together

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35
Q

What happens to the voltage as it passes through each component of a series circuit?

A

It decreases such that the sum of the voltage decreases is equal to the total voltage

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36
Q

How are the components arranged in a parallel circuit?

A

side by side and the ends are connected

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37
Q

Each component resistor is a parallel circuit receives the ___ voltage

A

same

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38
Q

What does the current passing through each component of a parallel circuit depend on?

A

its resistance

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39
Q

With each component added to a parallel circuit the total resistance _____.

A

decreases

40
Q

Component resistors connected in series have a ____ resistance and a ____ current flow

A

higher

lower

41
Q

Component resistors connected in parallel have a ____ resistance and a ____ current flow

A

lower

higher

42
Q

Is the electrical current that exists when electrons flow through human tissue a series or parallel circuit?

A

A combination or the 2

43
Q

What are the 3 types of current?

A
  • direct
  • alternating
  • pulsed
44
Q

What is a direct current?

A

an uninterrupted unidirectional flow of electrons toward the positive pole

45
Q

A direct current must last for at least how long?

A

1 second

46
Q

What can a direct current be used for clinically?

A
  • Iontophoresis
  • Wound healing
  • Stimulation of denervated muscle
47
Q

What is an alternating current?

A

the continuous or uninterrupted bidirectional flow of electrons

48
Q

Electrons flowing in an AC always move from _____ to _____ pole

A

negative to positive

49
Q

An alternating current must last for at least one second and also do what?

A

cross the isoelectric line at least twice in 1 second

50
Q

What can an alternating current be used for clinically?

A

Stimulation of denervated muscle

51
Q

What is a pulsed current?

A

the grouping of three or more pulses either unidirectionally or bidirectionally that are interrupted for short periods of time and repeat themselves at regular intervals

52
Q

What can a pulsed current be used for clinically?

A
  • IFC
  • Russian currents

*not for iontophoresis

53
Q

Describe monophasic waveform

A

current flow is on one side of the isoelectric line

54
Q

Describe biphasic waveform

A

current flow is first on one side of the isoelectric line and then changes to the opposite side

55
Q

What is a pulse?

A

an individual waveform

56
Q

What is a phase?

A

The portion of the pulse that rises in one direction either above or below the baseline for some period of time

57
Q

Because a direct current only have a single pulse duration and phase duration it is referred to as a ____ current

A

monophasic

58
Q

With direct current the terms single pulse duration and phase duration indicate what?

A

the length of time that current is flowing

59
Q

Because an alternating current produces waveforms that have two separate phases during each individual cycle it is referred to as a ____ current

A

biphasic

60
Q

Are pulsatile currents monophasic or biphasic?

A

They can be either

61
Q

In a PC single pulses are interrupted by what?

A

interphase intervals

62
Q

In a PC what does the pulse duration equal?

A

The sum of all phases plus the interphase interval

63
Q

In a PC the time during which the current is not flowing between the two phases is called what?

A

Interpulse interval

64
Q

What does a pulse’s amplitude refer to?

A

The intensity of the current with reference to the isoelectric line, with the maximum amplitude being the highest point of each phase

65
Q

Amplitude is synonymous with what 2 other terms?

A

“current intensity” and “voltage”

66
Q

How can average current be low with high peak amplitudes in a PC?

A

Due to long interpulse intervals

67
Q

What is pulse charge?

A

the total amount of electricity being delivered to the patient during each pulse

68
Q

The phase charge and the pulse charge are the same and always greater than zero in a ___phasic current

A

monophasic

69
Q

The pulse charge is equal to the sum of the phase charges in a ___phasic current

A

biphasic

70
Q

What is the net pulse charge on a symmetrical biphasic current?

A

zero

71
Q

What does phase duration indicate?

A

The elapsed time between the beginning and end of one phase

72
Q

What is pulse duration?

A

The elapsed time between the beginning and ending of all phases in a single pulse (aka pulse width)

73
Q

With ___phasic current, the phase duration is the same as the pulse duration.

A

monophasic

74
Q

With ___phasic current, the pulse duration is determined by the combined phase durations.

A

biphasic

75
Q

What does rise time refer to?

A

how quickly the pulse reaches its max amplitude in each phase

76
Q

What does decay time refer to?

A

the time in which a pulse goes from peak to zero volts

77
Q

The combined time of the pulse duration and the interpulse interval is referred to as what?

In other words what is the elapsed time from a given point on one pulse to the same point on the succeeding pulse referred to?

A

Pulse period

78
Q

What does pulse frequency indicate?

A

The number of pulses per unit of time

79
Q

What is a burst

A

a finite series of pulses over a finite interval of alternating current at a specific frequency over a specific period of time

80
Q

What does current modulation refer to?

A

Any alteration in the amplitude, duration, or frequency of the current during a series of pulses or cycles

81
Q

What are the 4 types of current modulation?

A
  • Continuous
  • Burst
  • Beat
  • Ramping
82
Q

Describe continuous current

A

The amplitude of current flow remains the same over time and is usually associated with long-pulse-duration monophasic current

83
Q

Describe burst modulation

A

Occurs when a PC or AC flows for a shirt duration and then is turned off for a short time

84
Q

What are the interruptions between individual burst called?

A

Interburst intervals

85
Q

Describe beat modulation

A

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

86
Q

How are the 2 pairs of electrodes arranged for beat modulation?

A

In a crisscrossed or cloverleaf-like pattern so the circuits interfere with one another

87
Q

Beat-modulated alternating current is referred to as what?

A

IFC or premodulated interferential

88
Q

Describe ramping modulation

A

The current amplitude will ramp up gradually to some preset maximum and may also ramp down in intensity

89
Q

What is the ramp-up time usually preset at?

A

About 1/3 of the on time

90
Q

Are motor nerves stimulated by a steady flow of direct current? Why or why not?

A

No, because the nerve repolarizes under the influence of the current and will not depolarize again until a sudden change in current intensity occurs

91
Q

What does frequency indicate?

A

The number of impulses (cycles) produced by an electrical stimulating device in 1 second and is referred to as cycles per minute (CPS)

92
Q

What two muscle characteristics are a function of the frequency?

A

The amount of shortening of the muscle fiber and the amount of recovery allowed to the fiber

93
Q

Increasing the intensity of the electrical stimulus causes what?

A

The current to reach deeper into the tissue

94
Q

Are high- or low-volt currents more capable of penetrating deeper into the tissue?

A

high-volt

95
Q

How can you stimulate more nerve fibers with the same intensity?

A

Adjust the duration of the treatment

96
Q

The negative electrode that has a high number of electrons is called what?

A

the cathode

97
Q

The positive electrode that has a low number of electrons is called what?

A

the anode

634: Electrotherapy Modalities (11 decks)

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