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THER EX > lecture 3: principles of electrical stimulating currents > Flashcards

lecture 3: principles of electrical stimulating currents Flashcards

1
Q

what are atoms that contain a positive (+) or negative (-) charge

A

ions

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2
Q

what is the unit of measure that indicates the rate at which electrical current flows

A

ampere

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3
Q

what is current described in

A

milliamperes (1/1000 ampere); or in microamperes (1/1,000,000 ampere)

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4
Q

what is the force resulting from an accumulation of electrons at one point in an electrical circuit, usually corresponding to a deficit of electrons at another point in the circuit

A

voltage

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5
Q

what is a resist current flow; fewer free electrons and greater resistance to electron flow

A

insulator

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6
Q

which law is the current in a circuit is directly proportional to the voltage and inversely proportional to the resistance

A

ohm’s law

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7
Q

Resistance of electrical flow depends on the characteristics of the ___

A

conductor

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8
Q

for electricity explained what is the resistance , the force and the flow

A

the force is the volt
the flow is the amp
the resistance is the ohm

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9
Q

is fat a conductor or insulator

A

great insulator

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10
Q

is the nerves a conductor or insulator

A

good conductor

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11
Q

what is the best electrical conductor in the body

A

blood

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12
Q

is a tendon a conductor or insulator

A

poor conductor

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13
Q

is a muscle a conductor or insulator

A

good conductor

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14
Q

what is the poorest conductor in the body

A

the bone

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15
Q

is the skin a conductor or insulator

A

insulator

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16
Q

what has the most resistance in the body (so good insulator)

A

tendon , ligament , bone and fat

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17
Q

what in the body has the least resistance (so good conductor)

A

nerves , blood and muscles

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18
Q

does frequency equal intensity

A

no

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19
Q

what is the correlation between electrical impedance vs frequency

A

as frequency goes up the impedance goes down

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20
Q

what are examples of alternating current

A

biphasic , TENS , IFC

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21
Q

how do electrons move in alternating currents

A

negative to positive

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22
Q

for alternating currents it is Neutralizes chemical reactions if “____ ”

A

balanced

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23
Q

what is direct current also called

A

galvanic current and monophasic

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24
Q

what is Uninterrupted unidirectional flow of electrons toward the positive pole (anode)

A

direct current

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25
Q

what is accumulated at each electrode for a direct current

A

chemicals

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26
Q

what is an example of direct current

A

iontophoresis

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27
Q

Instead of being one solid block of current, the current can be broken up into parts.. what is this called

A

pulses

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28
Q

what is pulsatile electrotherapeutic current

A

2 or more pulses grouped together

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29
Q

what is the direction of pulsatile current

A

could be unidirectional or bidirectional

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30
Q

what is most nerve/muscle stimulation currents

A

hi volt and russian currents

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31
Q

are pulsatile and hi volt and russian current continous or discontinuous

A

discontinuous

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32
Q

what in the body does not know the difference between AC and DC

A

nerves

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33
Q

with a continuous direct current when would a mm contraction occur

A

only when then current intensity rose to a stimulus threshold

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34
Q

Once the membrane repolarized, what would be needed to force another depolarization and contraction

A

another change in the current intensity

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35
Q

what is this called a fiber has been subjected to a constant level of depolarization will become unexcitable at that same intensity (amplitude).

A

accommodation phenomenon

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36
Q

what is the biggest difference in DC and AC

A

is the ability off direct current to cause chemical changes

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37
Q

Chemical effects from using direct current usually occur only when?

A

stimulus is continuous and is applied over a period of time (> 1 minute)

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38
Q

how is the resistance and current flow in a series electrical circuit

A

higher resistance and lower current flow

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39
Q

what are examples of series in the body

A

skin and fat

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40
Q

how is the resistance and current flow for a parallel electrical circuit

A

lower resistance and higher current flow

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41
Q

what are examples of parallel electrical circuits in the body

A

nerves, blood , mm , connective tissue and bone

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42
Q

what is the ion flow path

A

path of least resistance

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43
Q

is the path of least resistance the shortest path

A

not really

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44
Q

in electrical terms what is the frequency

A

how many cycles per second

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45
Q

in electrical terms what is intensity

A

increasing the stimulation or amplitude

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46
Q

in electrical terms what is pulse duration

A

changing the current pulse length to target specific structures

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47
Q

what is the ability of tissue to store electricity

A

capacitance

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48
Q

what is the least and more capacitance in the body

A

nerve is least and muscle tissue is the most

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49
Q

if something has a higher capacitance, how does that affect the response

A

longer before a response

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50
Q

the ___ the capacitance, the less the charge can be stored

A

lower

51
Q

changing the ___ or the lecrode distance can change the effects of skin impedance

A

frequency

52
Q

how can capacitance in a tissue be reduced

A

by increased stimulation frequency

53
Q

how would u rank these from lower capacitance to highest

muscle fibers
AB
Ao
mm tissue
C

A

lowest) A𝛃 < A𝛅 < C < muscle fiber < muscle tissue (highest)

54
Q

AC - ___ current; two separate phases during each cycle

A

biphasic

55
Q

AC - ___ current; two separate phases during each cycle

A

biphasic

56
Q

what applies to biphasic current; bidirectional flow during one cycle

A

cycle

57
Q

what is an individual waveform, applies to monophasic current

A

pulse

58
Q

DC - ____ (monophasic); current flows in the same direction either to positive or negative pole

A

unidirectional

59
Q

what is the intensity of the current stimulation

A

amplitude

60
Q

total current can be increased by increased what 2 things or a combo of both

A

increasing pulse duration or pulse frequency

61
Q

how is the duration pulse with a high amplitude rather then a low amplitude

A

short duration compared to a longer duration

62
Q

what is a monophasic pulse charge

A

phase charge and pulse charge are the sample and always > 0

63
Q

what is the time in which a pulse goes from peak amplitude to 0 V

A

decay time

64
Q

a fast pulse rise will have what kind of change in phase charge , ____ skin impedenace , and need ___ voltage to achieve same current flow

A

rapid change
lower
less

65
Q

what is the duty cycles

A

on-off time

66
Q

the more “___” time then the less muscle fatigue will occur

A

off

67
Q

what effect does the 1:1 ratio of duty cycle have on the mm

A

fatigues mm rapidly

68
Q

what affect does the 1:5 ratio of duty cycle have on mm

A

less mm fatigue

69
Q

what does 1:7 ratio of duty cycle mean

A

no fatigue (passive mm exercise)

70
Q

what is called the length of time current is flowing in one cycle

A

pulse duration

71
Q

what is the length of time current is off in one cycle

A

interpulse interval

72
Q

____ the duration can stimulate more nerve fibers when an adequate stimulation intensity is available to depolarize the membranes

A

Increasing

73
Q

what is the number of impulses or cycles produced by electrical stimulating device in 1 second

A

frequency

74
Q

what can frequency determine

A

the type of mm contraction elicited

75
Q

when does tetany occurs at

A

approx 55 pps (Hz)

76
Q

does tetanization depend on intensity

A

no

77
Q

Electrical impedance of the biological tissues is altered by what 3 things

A

the localizations and distance of the electrodes as a well as by the currents frequency

78
Q

Skin impedance ____ as the inter-electrode distance increases

A

increases

79
Q

Skin impedance ____ as frequency increases

A

decreases

80
Q

what is a combined pulses turned on and off for a short time in a repetitive cycle

A

burst modulation

81
Q

what modulation is a beat frequency produced by two interfering biphasic currents (AC) with different frequencies

A

beat modulation

82
Q

what modulation currently is the best for patient’s comfort

A

ramping modulation

83
Q

the higher the intensity means what to the current

A

it reaches deeper into the tissue

84
Q

what is a negative electrode; highest number of electrons

A

cathode

85
Q

what is a positive electrode; least number of
electrons

A

anode

86
Q

what has a Designate one electrode as negative and one as positive

A

monophasic

87
Q

what kind of polarity for mm contraction

A

negative active electrode

88
Q

the current density much be high enough to facilitate ____

A

depolarization

89
Q

if some electrodes are smaller then the other what happens to the current density under the smaller electrode

A

is increased

90
Q

what does the larger electrode size mean for current density

A

decreased current density

91
Q

how is the area of highest current density when electrodes are spaced close together

A

superficial

92
Q

how is the area of the highest current density when the electrodes are spaced further apart

A

deep

93
Q

where do u place the large electrode and smaller electrode

A

large electrode away from treatment area

smaller electrode to nerve or motor point

94
Q

Larger electrode disperses current over a ____ area

A

large

95
Q

Small electrode concentrates current over ___ ___

A

motor point

96
Q

which electrodes are used for smaller; current density is greater

A

active

97
Q

what electrodes are larger , current density is less

A

dispersive

98
Q

What kind of physiology response does Cathode (-) have

A

alkaline effect

99
Q

What kind of physiology response does Anode (+) have

A

acidic effect

100
Q

what physiologic response to electrical current

A

✧ Muscle contractions
✧ Modification of pain impulses

101
Q

what is the order for the action potiental

A
  1. stimulus at -70 mV
  2. depolarization
    3.repolarization
  3. hyper polarization
  4. resting state
102
Q

Remember the difference between Na+ and K+ ions moving inside and outside the cell- it creates a resting electrical charge of ______

A

-70 to -90 mV.

103
Q

what is the resting level of the action potential

A

-70 to -90 mV

104
Q

what does the action potential lead to

A

leads to depolarization. of the never

105
Q

a stimulus requires adequate ___ and ___ in order to create an action potential and depolarization

A

intensity and duration

106
Q

what is usually the site of depolarization

A

cathode (-)

107
Q

what makes cells membrane more positive

A

anode

108
Q

what are the 3 depolarization effects

A
  • nerves impulse reached effector organ (nerve or mm) and impulse is transferred between motor end plate or synapses e
  • NT is released
  • mm contraction
109
Q

what is the strength duration curve

A

a non linear relationship between current duration and current intensity

110
Q

what is Rheobase

A

intensity of current necessary to cause OBSERVABLE tissue response given a longer duration

111
Q

what is Chronaxie

A

duration required for a current of twice the intensity oh Rheobase to produce tissue excitation

112
Q

A𝛃 what type of nerve is this and is it thick or thin

A

sensory and thick

113
Q

A𝛅, what type of nerve is this

A

sharp pain

114
Q

C, what kind of nerve is this

A

dull

115
Q

A𝛃= sensory
C= dull pain
Denervated muscle
Motor
A𝛅= sharp pain

this these in order from thickest to thinnest

A

A𝛃= sensory
Motor
A𝛅= sharp pain
C= dull pain
Denervated muscle

116
Q

Difference sizes and types of nerve fibers have different thresholds for depolarization… what is the order of never from least to most

A

AB
motor
Ad
and then C

117
Q

nerves always depolarize in the same order… what is the order

A

• Sensory nerves
• Motor nerves
• Pain nerves
• Denervated muscle fibers

118
Q

do large or small diameter nerves depolarize first ? what about superifical or deep nerves

A

large and superficial

119
Q

what is the muscular response if there is a depolarization of motor nerve

A

mm contraction

120
Q

T/F: In the absence of nerve innervation, a muscle can still contract by using electrical current to depolarize the muscle membrane

A

t

121
Q

✧ Once a stimulus reaches a depolarizing threshold, nerve or muscle membrane depolarizes, and propagation of impulse occurs
✧ Stimulus causes depolarization or it does not. Reaction is the same regardless of the strength of the stimulus

that is this called

A

all or non response

122
Q

what is a denervated mm

A

lost its peripheral nerve supply

123
Q

a denervaeted mm …

✧___ in size
✧ ____ in tension generated with contraction
✧ ___ in time required for muscle contraction to occur

A

✧ Decrease in size
✧ Decrease in tension generated with contraction
✧ Increase in time required for muscle contraction to occur

124
Q

what is the goal of electrical stimulation for a denervated mm

A

help minimize the extent of atrophy while nerve is regenerating

THER EX (14 decks)

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