Quiz 1 Flashcards
Kinetic energy
energy that is moving (current)
potential energy
stored energy (static)
types is kinetic energy
1) thermal
2) mechanical
3) electrical
4) magnetic
types of potential energy
1) chemical
2) elastic
3) nuclear
4) gravitational
Conduction
direct energy transfer from object to object
convection
transfer of heat through air or liquids
conversion
the process of converting non-thermal energy into head
what is a current
movement of charged particles through a conductor because of a in response to an applied electrical field or voltage creating a physiological change
what are the predictable behaviors that charges follow
1) opposites attract
2) like charges repel
3) charges cant be created or distroyed
4) charges can transfer from one object to another
cation
positively charged ion
anion
a negatively charges ion
Coulombs Law
forces created by two particles are proportional to the strength and sign and inversely proportional to the distance (used to measure force of magnetic field)
Coulombs Law equation
F1=F2=Kc(q1+q2/R^2)
Voltage
the movement from potential energy to kinetic energy
electrical potential difference
potential energy that is converted into kinetic energy when particles are approximated (high potential - low potential)
what does current require
1) a driving force to move the particles (force generator)
2) a conductive pathway
3) a difference in electrical potential
OHMs law
current is directly proportional to voltage and inversely proportional to resistance
I=V/R
constant voltage
does not adjust voltage in response to impedance
constant current generator
adjusts voltage to impedance
Resistance
the opposition to direct current flow through a conductor
Capacitance
the ability of the conductor or insulator to start an electrical charge before an action potential occurs
what does the time constant of the cell membrane describe
the rise and decay of the membrane electrical potential. it is the product of the membranes resistance and capacitance, the minimal duration of the stimulus before threshold depolarization is reached.
what is impedance
opposite to alternating currents. the sum of thee resistance, capacitance and inductive components that can impair current flow. inversely proportional to frequency.
Series
resistors are placed end to end. The total resistance is equal to all of the components (V1+V2+V3) and the voltage decreases at each level (VD1+VD2+VD3)
parallel
resistors are placed side to side and the ends are connected. flow is inversely proportional to resistance of the pathway. Voltage is the sum of each component.
1/resistance total = 1/R1+1/R2+1/R3
Total voltage= V1=V2=V3
what part of the body is in series
electrode, skin and fat
what part of the body is in parallel
bone, muscle, blood, and nerve
what is the resting potential of a nerve
-70mv
why is a cell more negitively charged on the inside?
there is more Na2+ outside and more K+ inside the cell.
what is the threshold of excitation
-55 mv; when an increase of positive in the cell reaches its critical threshold and a thrust of Na2+ will enter the cell
what is the peak action potential of a nerve
+30 mv
Accomendation to an action potential
membrane remains depolarized and the action potential will not be evoked even if threshold is reached
what 2 things impact or determine if threshold is met
1) amplitude
2) duration (the time it takes the current to change cells voltage)
absolute refractory period
time for membrane to recover its excitability after AP is reached
Relative refractory period
period of time where higher stimulus may be needed for membrane to fire (0.5 msec and 1msec)
Rheobase
the minimum stimulus intensity; how much voltage or current is needed to stimulate tissue and how long it needs to be applied to get a responce
chronaxie
2x rheobase; pulse duration required for excitation
according to the strength duration curve what is the order of excitation
1) Alpha Beta and alpha - touch and proprioception
2) Motor
3) alpha delta (pain and temperature
4) C fibers (pain, temp, and itching)
physiologic effects of an intensity of 0-1 mA
Imperceptible
Physciologic effects of an intensiry of 2-15 mA
tingling sensation/muscle contraction
physiologic effects of an intensity of 16-100 mA
painful electrical shock
physiologic effects of an intensity of 101-200 mA
cardiac or respiratory arrest
physiologic effects of an intensity of >200
tissue buring or damage
Contraindications of all E stim
1) areas where it could interfere with another mechanical device (pacemaker)
2) acupuncture points, abdomine or LB of pregnant women
3) regions of known or suspected maligancy
4) active DVT or throbophlebitis
5) activly bleeding tissue or undtreated hemorrhagic disorders
6) infected tissue (TB or wounds with osteomyelitis)
7) recently radiated tissue
8) chest of someone with cardiax disease, arrhythmias or HF
9) neck or head of epilepsy patient
10) transcranially
11) reproductive organs
12) over eyes
13) anterior neck/carotid
14) damaged or at risk skin areas that can cause disruption in current
TENS specific contraindications
1) areas of impaired sensory awareness
2) cognitive or communication deficits
NMES specific contraindications
1) pregnant women
2) areas of impaired circulation
3) unstable area (osteoporpsis, fx, surgery)
4) chest, intercoastals and lower abdomen
Precausions for all E stim
1) active epiphysis
2) person with skin diseases
HVPC specific percausions
1) cognition or communication deficits
2) impaired sensation
3) impaired circulation
4) superficial regenerating nerves
5) chest wall or lower abdomen
NMES specific percausions
1) cognition or communication
2) impaired sensation
TENS specific percausions
1) impaired circulation
2) anterior chest wall or lower abdomen
Safe for all E stim
1) intact skin overlying implants containing metal, plastic, or cement
2) inflamed tissues as a result of injury or exasterbation of chronic inflammatory condition
Safe for TENS and HVPC specific
1) unstable areas (surgery, fx, orsteoporosis)
2) areas within or around chronic wounds or open wounds with localized infection
what to look for in skin prep
1) texture
2) wounds
3) cuts
4) allergies
5) dirt
6) OTC topicals
7) rashes
8) moles
9) scares
10) hair
11) tattoo
12) perfume
monopolar set up
1 treatment electrode and 2 disperse treatment electrode that is nNOT on the theraputic site and is larger in size. it allows for treatment when polarity is indicated
bipolar set up
2 treatment electrodes of equal sizes both in treatment areas. gives stronger contraction, covers more area and is more specific.
TENS specific electrode placement strategies
- over the site of pain
- through the site of pain (bracket)
- around the site
- Derms
- Myos
- peripheral nerve
- acupuncture or motor points
A delta fibers
small myelinated fibers that detect mechanical and thermal sensation. Gives sharp, stabbing, pricking sensation. short lasting
C fibers
unmylinated giving a broad range of stimuli. produces dull, aching, burning sensation.
what is the beginning point for processing pain
the dorsal root
Modes of TENS
1) conventional: high frequency, lower intensity
2) acupuncture: low frequency and high intensity
3) burst
4) brief intense; high frequency, duration and intensity
theories that support TENS
1) gait control: blocks A- delta and C-fiber input into dorsal horn
2) central inhibition (endogenous opioid): activation of descending inhibitory pathways
what does low frequency TENS target
mu opioid receptors (this can build tolerance)
what does high frequency TENS target
alpha (or delta) opioid receptors
balanced current
area of X = area of y
unbalanced current
area of X not equal to the area of y
alternating current
has both a positive pole and a negative pole
phase
current flow in one direction of an definite period of time
phase duration
the time from beginning to end of one phase of a pulse or cycle of alteranating current. (usec or msec)
pulse duration
beginning to the end of one pulse; includes phase duration and interphase interval
interphase interval
period of time with no electrical activity between 2 phases
interpalse interval
period of no electrical activity between 2 successive pulses
current density
intensity/ surface area under a pad. Smaller electrode the greater the intensity
what are the 3 things to modulate
1) amplitude (intensity/strength)
2) duration ( variable in phase or pulse duration)
3) frequency (variation in the number of series or pulses pps)
ramp or surge modulation
increase or decrease in phase change over time
duty cycle
ratio of on/off
what are the things that can me modilated in a burst
1) burst: series of pulses or cycles of alternating current during an “on” period
2) Burst duration
3) burst frequency: number of bursts per second
4) burst interval: the time the stimulator is “off”
what is the pulse diration equal too
1/frequency
direct current
current that lasts for at least 1 second
medium frequency alternating current
a continuous bidiractional flow of current
can be: russian or inferential
inferential current
2 sinoussoidal AC currents differing in frquency resulting in a beat
types of pulsatile current
1) mono or bi current
2) HVPC: high voltage pulsatile current
what is a Russian current
time modulated AC
purpose of Russian current
helps regain muscular strength if force is strong enough, regain ROM, decrease chronic edema
Russian current is not good for
1) small electrodes because of high RMS
2) applications where polarity is needed
pulsative current (PC)
non continuous flow or direct alternating current
types of PC
1) monophasic (high volt PC)
2) biphasic
3) polyphasic (used to refer to AC bursts)
what is PC HVPC (high voltage pulsate current)
twin peak pulse that are monophasic with very short duration (5-20 usec), high current amplitude (2000 to 250 mA). Short in duration with high amplitude
what is PC HVPC good for
1) polarity because it is monophonic
2) pain management
3) atrophy
4) chronic edema
what is PC HVPC not good for
1) large muscle groups
2) denervated muscle
3) iontrophoresis
what is RMS (root mean squared)
mathematical calculation for the amount of energy going into the tissue. Need to use the lowest amount of RMS to get the desired responce
High end RMS
10mA/cm area
low end RMS
1.5-4 mA/cm
what are currents that produce high RMS
1) russian (50-100mA/cm)
2) inferential (50-90 mA/cm)
what are currents that produce low RMS
1) monophasic PC (3-12 mA)
2) biphasic symmetrical PC (3-12mA)
3) high volt pulsed current (1.2-1.5 mA)
orthodromic AP movement
normal physiologic motion; AP moving in one direction. Sensory is from out to in and motor is from in to out
antidromic AP movement
not physciologic motion and can old get with e stim. AP movement in both direction
physciologic size principle of recruitment
small size to large size because the small motor neurons require less excitation to produce an AP
E stim size priniciple of recruitment
larger to smaller size because large motor neurons have low internal resistance
physiologic order of recruitment of muscle fiber types
slow twitch, fast resistance, fast fatigable
E stim order of recruitment of muscle fiber types
fast fagtigable, fast resistant and slow twitch
what is critical fusion
Frequency required for muscle to get a tetanic contraction. If you do not hit critical fusion then you will just see muscle fasciculations.
distance of the electrodes
the more spread out the electrodes are from each other the deeper the stimulation will be.
what does the strength duration curve state
that their is a predicatble oder of recruitment (sensory, then motor, then pain)
what is the frequency needed for a smooth contraction?
30 pps
purpose of On/Off ratio
allows for rest of recruited motor units offsetting synchronous effect and order of recruitment effect
what is optimal recruitment
volitional contraction and e stem together (working on all of the muscle fibes)
uses of NMES
1) FES
2) ROM
3) spasmolysis
4) neuro re edu
5) edema reduction
what is the purpose of FES (functional electrical stim)
provide orthotic support
what are the clinical indications for FES
scoliosis, hemi-shoulder sublux, AFO
what are the contraindications for FES
joint or bone instability, poor cognition, poor sensation, not motivated to try, must have above a 0 MMT
what are the special considerations for scoliosis
- curve of 20-45 degrees
- spinal growth postential of at least 1 year, idiopathic, progressive, cooperation and compliance, tolerant to e-stim
what are the uses for E stim when targeting ROM
- in absence of boney abnormality
- results can be seen for 2 weeks
- optimal for elbow wrist and knee
- preserve ROM you need to get 50-100 reps through full range
- to gain ROM you need to get 200 reps
- amp must be at low levels to avoid jamming the joint
NMES methods for ROM
- active stretch with antagonist recruitment
- supplement for voluntary movement
- supplement through full range with weak movement
when is spasmolysis NMES indicated
1) acute spasm secondary to MSK injury ( low-level stim, at leadt 1 MMT, small stimulated muscle contractions, similar to mechanism of a spastic muscle
2) spasm secondary to UMN lesion
techniques for spasticity control
1) ES to antagonist
2) ES to agonist
3) ES to both
ES to antagonist
immediate effect for up to 1 hour, Long term reduction of spasm, uses the principle of reciprocal inhibition
ES to agonist
last sevel hours, will not be permanent, muscle contractions (orthodromic) and spinal reflex (antidromic) giving longer lasting modulation of spastic tone, stimulate renshaw cells for inhibiting Alpha motor neurons, start at a high ramp and slowly ramp down
ES to antagonist and agonist specifically used when
spasticity limited to one or two muscle groups only, short neurogentic inhibition
when is re edu NMES indicated
- poor force
- poor voluntary control
- inability to recruit
- always includes voluntary effort
what is the effect of re edu NMES
immediate; no maximum contractions and stim is tolerable
what are the 2 mechanisms for NMES edema reduction
1) HVPC: pumping action of skeletal muscles
2) HVPC: high sensory levels Cathodal
what is cataphoriesis
movement of colloid molecules toward cathode repelling albumin and shifting edema
critical fusion for postural muscles
13-15 pps
critical fusion for phasic muscles
30 pps
when is critical fusion plateu reached to get fatigue
50-80 pps
what are the 2 types of overload in the overload principle
1) adaptation to prolonged low level activity
2) adaptation to intermittent high force level activity
what does adaptation to prolonged low level activity do to the body
makes the body more efficient to provideing ATP, increasing 02 and increasing metabolic function
what does adaptation to intermittent high force level activity do to the body
increases action and myosin content
rapid fatigue duty cycle
1:1 (50%)
little fatigue duty cycle
1:5 (16.6%)
what duty cycle ratios are used to avoid ishemia and increase blood flow
1:1 and 1:2
what is a 1:3 duty cycle in percentage
25%
how to establish MVIC for patients
best of 3 reps of isometric contraction of involved muscle. train at 60-80%
