lecture 3: principles of electrical stimulating currents Flashcards
1
Q
what are atoms that contain a positive (+) or negative (-) charge
A
ions
2
Q
what is the unit of measure that indicates the rate at which electrical current flows
A
ampere
3
Q
what is current described in
A
milliamperes (1/1000 ampere); or in microamperes (1/1,000,000 ampere)
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
5
Q
what is a resist current flow; fewer free electrons and greater resistance to electron flow
A
insulator
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
7
Q
Resistance of electrical flow depends on the characteristics of the ___
A
conductor
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
9
Q
is fat a conductor or insulator
A
great insulator
10
Q
is the nerves a conductor or insulator
A
good conductor
11
Q
what is the best electrical conductor in the body
A
blood
12
Q
is a tendon a conductor or insulator
A
poor conductor
13
Q
is a muscle a conductor or insulator
A
good conductor
14
Q
what is the poorest conductor in the body
A
the bone
15
Q
is the skin a conductor or insulator
A
insulator
16
Q
what has the most resistance in the body (so good insulator)
A
tendon , ligament , bone and fat
17
Q
what in the body has the least resistance (so good conductor)
A
nerves , blood and muscles
18
Q
does frequency equal intensity
A
no
19
Q
what is the correlation between electrical impedance vs frequency
A
as frequency goes up the impedance goes down
20
Q
what are examples of alternating current
A
biphasic , TENS , IFC
21
Q
how do electrons move in alternating currents
A
negative to positive
22
Q
for alternating currents it is Neutralizes chemical reactions if “____ ”
A
balanced
23
Q
what is direct current also called
A
galvanic current and monophasic
24
Q
what is Uninterrupted unidirectional flow of electrons toward the positive pole (anode)
A
direct current
25
what is accumulated at each electrode for a direct current
chemicals
26
what is an example of direct current
iontophoresis
27
Instead of being one solid block of current, the current can be broken up into parts.. what is this called
pulses
28
what is pulsatile electrotherapeutic current
2 or more pulses grouped together
29
what is the direction of pulsatile current
could be unidirectional or bidirectional
30
what is most nerve/muscle stimulation currents
hi volt and russian currents
31
are pulsatile and hi volt and russian current continous or discontinuous
discontinuous
32
what in the body does not know the difference between AC and DC
nerves
33
with a continuous direct current when would a mm contraction occur
only when then current intensity rose to a stimulus threshold
34
Once the membrane repolarized, what would be needed to force another depolarization and contraction
another change in the current intensity
35
what is this called a fiber has been subjected to a constant level of depolarization will become unexcitable at that same intensity (amplitude).
accommodation phenomenon
36
what is the biggest difference in DC and AC
is the ability off direct current to cause chemical changes
37
Chemical effects from using direct current usually occur only when?
stimulus is continuous and is applied over a period of time (> 1 minute)
38
how is the resistance and current flow in a series electrical circuit
higher resistance and lower current flow
39
what are examples of series in the body
skin and fat
40
how is the resistance and current flow for a parallel electrical circuit
lower resistance and higher current flow
41
what are examples of parallel electrical circuits in the body
nerves, blood , mm , connective tissue and bone
42
what is the ion flow path
path of least resistance
43
is the path of least resistance the shortest path
not really
44
in electrical terms what is the frequency
how many cycles per second
45
in electrical terms what is intensity
increasing the stimulation or amplitude
46
in electrical terms what is pulse duration
changing the current pulse length to target specific structures
47
what is the ability of tissue to store electricity
capacitance
48
what is the least and more capacitance in the body
nerve is least and muscle tissue is the most
49
if something has a higher capacitance, how does that affect the response
longer before a response
50
the ___ the capacitance, the less the charge can be stored
lower
51
changing the ___ or the lecrode distance can change the effects of skin impedance
frequency
52
how can capacitance in a tissue be reduced
by increased stimulation frequency
53
how would u rank these from lower capacitance to highest
muscle fibers
AB
Ao
mm tissue
C
lowest) A𝛃 < A𝛅 < C < muscle fiber < muscle tissue (highest)
54
AC - ___ current; two separate phases during each cycle
biphasic
55
AC - ___ current; two separate phases during each cycle
biphasic
56
what applies to biphasic current; bidirectional flow during one cycle
cycle
57
what is an individual waveform, applies to monophasic current
pulse
58
DC - ____ (monophasic); current flows in the same direction either to positive or negative pole
unidirectional
59
what is the intensity of the current stimulation
amplitude
60
total current can be increased by increased what 2 things or a combo of both
increasing pulse duration or pulse frequency
61
how is the duration pulse with a high amplitude rather then a low amplitude
short duration compared to a longer duration
62
what is a monophasic pulse charge
phase charge and pulse charge are the sample and always > 0
63
what is the time in which a pulse goes from peak amplitude to 0 V
decay time
64
a fast pulse rise will have what kind of change in phase charge , ____ skin impedenace , and need ___ voltage to achieve same current flow
rapid change
lower
less
65
what is the duty cycles
on-off time
66
the more “___” time then the less muscle fatigue will occur
off
67
what effect does the 1:1 ratio of duty cycle have on the mm
fatigues mm rapidly
68
what affect does the 1:5 ratio of duty cycle have on mm
less mm fatigue
69
what does 1:7 ratio of duty cycle mean
no fatigue (passive mm exercise)
70
what is called the length of time current is flowing in one cycle
pulse duration
71
what is the length of time current is off in one cycle
interpulse interval
72
____ the duration can stimulate more nerve fibers when an adequate stimulation intensity is available to depolarize the membranes
Increasing
73
what is the number of impulses or cycles produced by electrical stimulating device in 1 second
frequency
74
what can frequency determine
the type of mm contraction elicited
75
when does tetany occurs at
approx 55 pps (Hz)
76
does tetanization depend on intensity
no
77
Electrical impedance of the biological tissues is altered by what 3 things
the localizations and distance of the electrodes as a well as by the currents frequency
78
Skin impedance ____ as the inter-electrode distance increases
increases
79
Skin impedance ____ as frequency increases
decreases
80
what is a combined pulses turned on and off for a short time in a repetitive cycle
burst modulation
81
what modulation is a beat frequency produced by two interfering biphasic currents (AC) with different frequencies
beat modulation
82
what modulation currently is the best for patient’s comfort
ramping modulation
83
the higher the intensity means what to the current
it reaches deeper into the tissue
84
what is a negative electrode; highest number of electrons
cathode
85
what is a positive electrode; least number of
electrons
anode
86
what has a Designate one electrode as negative and one as positive
monophasic
87
what kind of polarity for mm contraction
negative active electrode
88
the current density much be high enough to facilitate ____
depolarization
89
if some electrodes are smaller then the other what happens to the current density under the smaller electrode
is increased
90
what does the larger electrode size mean for current density
decreased current density
91
how is the area of highest current density when electrodes are spaced close together
superficial
92
how is the area of the highest current density when the electrodes are spaced further apart
deep
93
where do u place the large electrode and smaller electrode
large electrode away from treatment area
smaller electrode to nerve or motor point
94
Larger electrode disperses current over a ____ area
large
95
Small electrode concentrates current over ___ ___
motor point
96
which electrodes are used for smaller; current density is greater
active
97
what electrodes are larger , current density is less
dispersive
98
What kind of physiology response does Cathode (-) have
alkaline effect
99
What kind of physiology response does Anode (+) have
acidic effect
100
what physiologic response to electrical current
✧ Muscle contractions
✧ Modification of pain impulses
101
what is the order for the action potiental
1. stimulus at -70 mV
2. depolarization
3.repolarization
4. hyper polarization
5. resting state
102
Remember the difference between Na+ and K+ ions moving inside and outside the cell- it creates a resting electrical charge of ______
-70 to -90 mV.
103
what is the resting level of the action potential
-70 to -90 mV
104
what does the action potential lead to
leads to depolarization. of the never
105
a stimulus requires adequate ___ and ___ **in order to create an action potential and depolarization**
intensity and duration
106
what is usually the site of depolarization
cathode (-)
107
what makes cells membrane more positive
anode
108
what are the 3 depolarization effects
- 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
what is the strength duration curve
a non linear relationship between current **duration** and current **intensity**
110
what is Rheobase
intensity of current necessary to cause OBSERVABLE tissue response given a longer duration
111
what is Chronaxie
duration required for a current of twice the intensity oh Rheobase to produce tissue excitation
112
A𝛃 what type of nerve is this and is it thick or thin
sensory and thick
113
A𝛅, what type of nerve is this
sharp pain
114
C, what kind of nerve is this
dull
115
A𝛃= sensory
C= dull pain
Denervated muscle
Motor
A𝛅= sharp pain
this these in order from thickest to thinnest
A𝛃= sensory
Motor
A𝛅= sharp pain
C= dull pain
Denervated muscle
116
Difference sizes and types of nerve fibers have different thresholds for depolarization… what is the order of never from least to most
AB
motor
Ad
and then C
117
nerves always depolarize in the same order… what is the order
• Sensory nerves
• Motor nerves
• Pain nerves
• Denervated muscle fibers
118
do large or small diameter nerves depolarize first ? what about superifical or deep nerves
large and superficial
119
what is the muscular response if there is a depolarization of motor nerve
mm contraction
120
T/F: In the absence of nerve innervation, a muscle can still contract by using electrical current to depolarize the muscle membrane
t
121
✧ 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
all or non response
122
what is a denervated mm
lost its peripheral nerve supply
123
a denervaeted mm …
✧___ in size
✧ ____ in tension generated with contraction
✧ ___ in time required for muscle contraction to occur
✧ Decrease in size
✧ Decrease in tension generated with contraction
✧ Increase in time required for muscle contraction to occur
124
what is the goal of electrical stimulation for a denervated mm
help minimize the extent of atrophy while nerve is regenerating
