Basic Principles of Electricity Jennifer L. Doherty-Restrepo, MS, LAT, ATC FIU Entry-Level ATEP PET 4995: Therapeutic Modalities

Electromagnetic Spectrum b Electrical Stimulating Currents Commercial Radio and Television Shortwave Diathermy Microwave Diathermy Infrared LASER Visible Light Ultraviolet Ionizing Radiation { Longest LongestWavelength Shortest ShortestWavelength Lowest LowestFrequency Highest HighestFrequency

Electrons b b Particles of matter possessing a ________ charge and a small ________ b b Net movement of electrons is an ________ ________ b b Electrons will move from ________ to ________ energy levels Establishes an electrical ________

Electrical Potential Difference b b Difference in ________ of electrons between two points b b Electrons will not move unless a ________ difference exists

Ampere b b Unit of measure which indicates _____ at which electrons flow 1 _____ = movement of 1 coulomb or 6.25x10 18 electrons /sec b b Current flow is typically described as: ________ (1/1000 of an amp), or ________ (1/1,000,000 or an amp)

Volt b b Creates the electrical potential ________ b b The __________ ________ which must be applied to create flow of electrons b b Commercial current (wall outlets) is either ________ or ________

Conductors b b Materials that permit ______ movement of electrons b b Composed of large numbers of ________ electrons b b Offer ________ resistance to current flow b b Good conductors: Metals (copper, gold, silver, aluminum) Electrolyte solutions

Insulators b b Materials that ______ the flow of electrons b b Contain ________ free electrons b b Insulator materials: Air, Wood, and Glass

Resistance = Electrical Impedance b b ________ to flow of electrical current b b Measured in ________ Unit of measure indicating resistance to current flow b b Ohm’s law: current flow is ________ proportional to ________ and ________ proportional to ________ Current flow = Voltage Resistance

Watt b b Measure of electrical ________ b b Electrical ______ is the product of ______ (electromotive force) and the amount of current flowing Watts = volts X amps b b Indicates the ________ at which electrical power is being used

Electrotherapeutic Currents b b 3 types of currents capable of producing specific physiological effects ________ b b Therapeutic effects of will be discussed in Chapter 8

Direct Current (DC) b Uniterrupted, uniderectional flow of electrons in the ________ direction b Also called ________ currents b Sometimes called ________ currents

Alternating Current (AC) b Continuous flow of electrons changes direction Always flows from ________ to ________ pole until polarity is reversed b Also called ________ currents

Pulsitile (Polyphasic) Currents b ________ electrical current that contains __ or more grouped phases in a single pulse b Also called ________ and ________ currents

Electrical Generators b b Transcutaneous Electrical Nerve Stimulators (TENS) Stimulates ________ ________ b b Neuromuscular Electrical Stimulator (NMES) = Electrical Muscle Stimulator (EMS) Stimulates ________ b b Microcurrent Electrical Nerve Stimulators (MENS) = Low Intensity Stimulators (LIS) Assists the ________ ________ b All Are Transcutaneous Electrical Stimulators!

Electrotherapeutic Currents b b No relationship between type of current used to power the generator and the type of current transmitted to patient b b Generators may be powered by AC or DC Batteries = DC between V Wall outlet = AC at 120 or 220V at 60 Hz

Waveform or Pulse b Pulse = ________ ________ b Phases (duration) b Interpulse interval b Direction (polarity) b Amplitude b Rate of ________ Accommodation

Symmetrical Waveforms b Sine b Square b Triangular b Spiked b ____ and _____ of each phase is identical

Symmetrical Waveforms b Twin peaked triangular waveform Found on most high volt generators

Asymmetric Waveforms b ________ No longer used Effects were similar to DC pulsed wave b ________ Sawtooth Used to stimulate denervated muscle

Current Modulation b (A) Continuous b (B) Interrupted b (C) Burst Packets (envelopes) Pulse trains Beats b (D) Ramped (Surge)

Pulse Amplitude b Amplitude = current intensity = voltage b ______ ______ = amount of current flowing per unit time Determined by interpulse interval or current duration b Measured in ________ or ________

Pulse Duration b b Length of ________ current is flowing b b Monophasic current: ______ ______ = ______ ______ b b Biphasic current: Pulse duration is determined by the combined ______ durations b b Polyphasic current: The combined pulse duration and interpulse interval is the ______ ______

Pulse Frequency b Number of or per second b Number of ______ or ______ per second Measured as pulses per second (PPS)Measured as pulses per second (PPS) b Individual pulse = rise and fall in amplitude b As frequency, amplitude and more rapidly b As frequency ___________, amplitude ________ and ________ more rapidly

Pulse Frequency b Effects the type of muscle contraction Pulse rate of less than ___ pps = muscle twitch Pulse rate equal to or greater than ___ pps = tetany b Effects the mechanism of pain modulation

Electrical Circuits b b Path of current from power source through various components back to generating source ______ ______ : electrons are flowing ______ ______ : current flow ceases b b Components of electrical circuits ______ ______: capable of producing voltage _________ _________: along which current travels _________ _________: providing resistance to electrical flow

Series Circuit b Only ______ path for current to take b Component resistors placed ______ to ______ b Total resistance = sum of resistances b Total voltage = sum of voltage decreases

Parallel Circuit b Component resistors placed ___ to ___ and the ___ are connected b Current chooses path with least _________

Series Circuit vs. Parallel Circuit b Component resistors in a series circuit have a resistance and current flow b Component resistors in a series circuit have a ____ resistance and _____ current flow b Component resistors in a parallel circuit have a resistance and a current flow b Component resistors in a parallel circuit have a _____ resistance and a _____ current flow

Current Flow Through Biologic Tissues b Combination of both series and parallel circuits b Tissue highest in water and ion content are the best conductors Bood, nerve, muscle, tendon, skin, fat, bone

Physiologic Responses to Electrical Current b Thermal All electrical currents cause a in tissue temperatureAll electrical currents cause a ____ in tissue temperature Electrical currents used to stimulate nerve and muscle produce thermal effectsElectrical currents used to stimulate nerve and muscle produce _______ thermal effects b Chemical At pole, negatively charged particles cause an reactionAt ______ pole, negatively charged particles cause an ______ reaction –Protein coagulation and hardening of tissues At pole, positively charged particles cause an reactionAt ______ pole, positively charged particles cause an ______ reaction –Liquefying protein and softening of tissues

Safety In Using Electrical Equipment

Ground Fault Interrupters (GFI)   Constantly compare amount of electricity flowing from wall outlet to whirlpool turbine with the amount returning   GFI will interrupt current flow in as little as 1/40 of a second

Summary b Terminology b Ohm’s Law Relationship between voltage and resistanceRelationship between voltage and resistance b Different types of current are capable of producing specific physiologic changes Thermal or chemicalThermal or chemical b Current modulation