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Modalities > Principles of Electricity > Flashcards

Principles of Electricity Flashcards

1
Q

electricity

A

a fundamental form of energy observable in positive and negative forms that occurs naturally or is produced

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2
Q

types of electricity

A
  • static: friction between two objects, one gains electrons and one loses electrons
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3
Q

current electricity

A
  • current flow: movement of electrons, bees to a hive
  • volts and amps (intensity)
  • electrons flow through a circuit
  • conductors: allow the current to pass through
  • insulators: block the current flow
  • resistors: let some flow through, slow flow down (ohms)
  • watt: the amour of work that is done as amps are pushed by volts
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4
Q

voltage (V)

A
  • amount of electrical pressure
  • the potential to cause current: the potential to cause something electrical to happen
  • 12V car battery has 12V of potential
  • a 120V wall outlet has potential, but nothing happens unless you plug something in and turn it on
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5
Q

amperage (A)

A
  • volume of electricity that flows past a particular point in a given period of time
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6
Q

electrical current (I)

A
  • the rate as which charge flows through a cross section of a conductor in a unit time
  • quantity of charge (coulomb/time)
  • on an e-stem unit, when you turn the knob that increases the intensity of the current, you are increasing the amps
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7
Q

volt

A
  • a uit of force required to push a current of 1 amp (A) through the resistance of 1 ohm
  • volts, ot voltage, can come from batteries or a generator
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8
Q

Ohm’s law

A
  • a relationship between current, voltage, and resistance
  • current is directly proportional to voltage and inversely proportional to resistance
  • V=IR
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9
Q

closed circuit

A
  • a closed circuit is formed when a complete path is formed between two poles
  • positive pole= anode
  • negative pole= cathode
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10
Q

non-biologic insulators

A
  • glass, rubber, oil, asphalt, fiberglass, porcelain, ceramic, quartz, dry cotton, dry paper, dry wood, plastic, air, diamond
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11
Q

non-biologic conductors

A
  • silver, copper, gold, aluminum, iron, steel, brass, bronze, mercury, graphite, dirty water, concrete
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12
Q

biologic tissues

A
  • blood and nerves: high electron flow= low electrical impedance (easiest for it to pass through)
  • muscle: medium electron flow, medium impedance
  • skin, adipose tissue, and bone: low electron flow, high impedance
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13
Q

lowering impedance for electrode application

A
  • clean skin with alcohol
  • ask athlete to avoid use of lotion
  • electrodes should be lubricated
  • limit hair under electrode
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14
Q

Other factors determining impedance

A

length of circuit

  • the shorter the distance that an electron has to travel, the less resistance to current flow
  • want it to be closer together

the resistance of an electrical circuit path is inversely proportional to its cross sectional diameter
- greater cross sectional area of a path, the less resistance to current flow

increasing temp of tissue
- decreases the resistance to current flow.

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15
Q

types of electrical stimulation currents:

Direct current

A
  • direct currents (galvanic current): uninterrupted flow of electrons, either completely above or below line
  • electrons travel cathode to anode
  • properties of electrical flow: amplitude: maximum distance, pulse duration: horizontal distance, pulse charge: area within the waveform
  • used to produce local polarity-based changes in human tissue
  • iontophoresis
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16
Q

types of electrical stimulation currents:

Alternating current

A
  • direction of current flow changes from positive to negative in a cyclical manner (no true positive or negative pole)
  • basic pattern is a sine wave
  • amplitude: peak to peak
  • frequency: cycles per second (Hz)
  • cycle duration: inversely related to frequency
17
Q

types of electrical stimulation currents:

Pulsed currents

A
  • monophasic current: unidirectional flow of electrons. pulses have one phase per pulse. either positive or negative
    useful for creating involuntary muscle contractions and pain control
  • biphasic currents: bidirectional flow of electrons marked by periods of non-current flow. each pulse has 2 phases (one on each side of isoelectric line)
    unbalanced phases: 2 phases d not carry equal charges so there will be either positive or negative charge effect. comfortable
    balanced: phases carry equal charges. normally painful
18
Q

pulse duration

A
  • monophasic current: pulse duration = phase duration
  • pulse duration includes horizontal distance from beginning to end of the final phase including intrapulse interval
  • measures in microseconds
  • pulse width determines which nerve fibers are recruited optimally
19
Q

interpulse interval

A
  • time between the conclusion of one pulse and the start of another
  • always longer in duration than intrapulse interval
  • tissues have chance to complete mechanical events and recharge
  • pulse period = one pulse + the inter pulse interval
20
Q

pulse charge

A
  • measure the number of electrons contained within a pulse (area)
  • each phase carries its own charge
  • the higher the phase charge, the stronger the contraction
21
Q

pulse rise

A
  • amount of time it takes for the pulse to reach its peak value
  • if goal is to stimulate alpha neurons, you need a rapid pulse rise
22
Q

pulse trains

A
  • low TENS: prevents muscle fatigue

- high TENS: prevents accommodation

23
Q

amplitude ramp

A
  • ramp up: allows for gradual muscle contraction
  • ramp down: allows for gradual relaxation
  • gradually work patient up to stronger amplitude
24
Q

circuit series

A
  • series: electrical current flows along one set route, each component has same amperage, but voltage varies. current enters body through series circuit
  • parallel: electrons are provided with alternative paths to follow. electrons take the path of least resistance. once current is through skin may take different paths
25
Q

current density

A
  • current density is inversely proportional to the size of the electrode
  • amount of current per units area
26
Q

duty cycle

A
  • the amount of time the current is flowing (on) as opposed to the amount of time the current is not (off)
27
Q

electrode placement

A
  • stimulation points:
    motor points: area where the muscle is most easily excited with the minimum amount of stimulation. where motor nerve enters the muscle
    trigger points: palpable nodules in taut bands of muscle fibers
    acupunture points: energy that flows across the meridians is chi
28
Q

proximity of electrodes

A
  • too close: skin stimulation
  • far enough: deeper stimulation into tissues
  • too far: no specific tissues targeted
29
Q

bipolar technique

A
  • use of 2 electrodes, or two sets of electrodes
  • equal in size, equal amounts of stimulation occurs under each electrode
  • increased impedance might cause unequal stimulation
30
Q

monopolar technique

A
  • uses one or more active electrodes placed over the target tissue
  • dispersive pad: place outside of treatment area and must be 2.5x bigger
  • current density focuses under smaller electrode
31
Q

quadripolar technique

A
  • 2 bipolar circuits, each originating from its own channel
  • channel 1: 2 electrodes same size (proximal quad)
  • channel 2: 2 electrodes same size (distal quad)
  • each channel has its own intensity control
32
Q

nerve depolarization factors

A
  1. the diameter of the nerve fiber- sensory Aβ fibers, motor nerves, Aδ and C fibers
  2. the depth of the nerve fiber in relation to the electrode (the deeper the nerve the harder to depolarize)
  3. the duration of the pulse or phase- (the shorter the pulse/phase, the more intensity that can be delivered)
33
Q

stimulation levels

A
  • subsensory: intensity is increased to the point that the patient starts to feel sensation, then reduced slightly (10%)
  • sensory: intensity is increased until a slight twitch is felt, then reduced slightly
  • motor: intensity is increased until visible, non-painful muscle contraction is achieved
  • noxious: intensity is increased until pain fibers are stimulated
34
Q

the law of Dubois Reymond

A
  • current must be of sufficient intensity to cause depolarization of the cell membrane
  • rate of rise of the leading edge of the pulse must be rapid (steep) enough to prevent accommodation
  • duration of the current must be long enough in one direction that the nerve has time to depolarize
  • sufficient time must be allowed to allow for repolarization
35
Q

E-stem uses/goals in AT

A
  • muscle contraction: precent atrophy, neuromuscular re-education, edema reduction
  • pain control: gate control theory, noxious pain to induce descending mechanisms
  • emeda reduction
36
Q

contraindications

A
  • cardiac dysfunction: do NOT stimulation of thorax and neck
  • pacemakers: do NOT put stimulation over implant site
  • pregnancy: do NOT put stimulation over back, abdomen, or pelvic girdle
  • do NOT use on cancerous lesions, infected tissue, exposed metal implants, unstable fractures
37
Q

precautions

A
  • menstruation: stimulation over abdomen, beck, pelvic girdle may increase hemorrhage
  • nerve sensitivity: carotid sinus, esophagus, larynx/pharynx, eyes, upper thorax, temporal region
  • communication impairments
  • severe obesity
  • electronic monitoring equipment

Modalities (4 decks)

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