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Physical Agents > Lecture #4 > Flashcards

Lecture #4 Flashcards

1
Q

Electricity has an effect on each cell that it passes through. What type of response to the electricial should the cell have?

A

In a similar manner to how the cell functions or grows.

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2
Q

What will too much electrical current density cause to tissues?

A

The destruction of the tissue.

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3
Q

Biological response in the tissues are dependent on: (x5)

A

Pulse length, rate of rise and decay, length of time between pulses, modulation of pulses, and amplitude of pulse.

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4
Q

How does electrical stim facilitate muscular contractions?

A

Through nerve or muscle excitation.

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5
Q

What is the gate theory?

A

Stimulating sensory nerves to block pain to help control the pain.

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6
Q

What type of stim helps tissue to heal by creating an electrical field?

A

Galvanism

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7
Q

What type of stim uses an electrical field on the skin surface to drive ions (beneficial for healing) through the skin?

A

Ionto

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8
Q

What are the different things that can be accomplished using electrical stim in rehab? (x4)

A

Facilitate muscular contractins, pain control, tissue healing, and using an electrical field to drive ions.

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9
Q

What are the three levels in which the patient will perceive the excitatory responses?

A

Electrical sensation -> Muscular contraction -> Electric pain

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10
Q

If the electrical energy is sufficient enough in its magnitude to cause the depolarization of the nerve membrane, then what will happen?

A

An action potential

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11
Q

What are the four levels of changes that occur in the body during electrical stimulation?

A

Cellular level, tissue level, segmental level, and systematic level.

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12
Q

What are the changes that occur at the cellular level during e-stim? (x5)

A

Excitation of nerves, changes in cell membrane permeability, protein synthesis, stimulation of blastic activity (fibroblast, osteoblast), and modification of microcirclation.

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13
Q

What are the changes that occur at the tissue level during e-stim? (x3)

A

Skeletal muscle contraction, smooth muscle contraction, and tissue regeneration (galvanic current).

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14
Q

What are the changes that occur at the segmental level during e-stim? (x4)

A

Modification of joint mobility (“feeding yourself”), pumping to alter the circulation and lymph flow, alteration of the microvascular system, and increased movement of charged proteins in the lymph system (galvanic current).

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15
Q

What are the changes that occur at the systematic level during e-stim? (x2)

A

Analgesic effect as endogenous pain suppressors are released, and analgesic effect from the stimulation of neurotransmitters to control pain stimuli (gate theory)

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16
Q

What is the excitability of of the cell dependent upon?

A

The voltage-sensitive permeability of the cell membrane.

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17
Q

What is the resting potential of the cell membrane?

A

The potential difference between the inside and outside of the cell due to the unequal distribution of charged ions on each side of the cell membrane. There are negatively charged ions inside the cell and positively charged ions on the outside of the cell. This is how the cell maintains homeostatis.

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18
Q

What does the sodium potassium pump do?

A

It actively pumps out positively charged ions while allowing negatively charged ions to enter the cell. It also pumps out sodium and allows potassium to enter.

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19
Q

What is the resting membrane potential of cells?

A

-70 to -90 mV

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20
Q

What is an action potential?

A

A recorded change in electrical potential between the inside and outside if a nerve cell resulting in muscular contraction.

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21
Q

True or False: not all stimuli are effective in causing an action potential and depolarization.

A

True: the stimulus will only cause depolarization and an action potential if the stimulus is great enough to need or exceed the membranes threshold for excitation.

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22
Q

What electrode typically causes depolarization? Why?

A

The cathode (negative electrode) because the negative ions lowers the cell membrane’s resting potential below threshold.

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23
Q

What electrode is normally considered the active electrode?

A

The cathode.

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24
Q

What electrode is the dispersive (or indifferent) electrode?

A

The anode.

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25
Q

What increases the threshold necessary for depolarization?

A

The positive charges from the anode.

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26
Q

What is the time after cell excitation and depolarization in which a nerve is unable to transmit an second impulse?

How long does this last?

A

The absolute refractory period.

0.5 nanoseconds

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27
Q

How many times a second could a nerve possible discharge?

A

1,000

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28
Q

What occurs when the intensity is great enough to have all the muscle divers contract synchronously?

A

Tetany

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29
Q

The nerve impulse travels to what part of the muscle in which it then causes a neurotransmitter to be released that stimulates a muscle twitch?

A

The motor end plate.

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30
Q

Stimuli of short duration require greater of this, according to the strength-duration curve, in order to reach nerve and muscle cell threshold.

A

Current amplitude

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31
Q

What is the minimum amount of intensity from a current needed for tissue excitation when given the maximum duration?

A

Rheobase

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32
Q

What is the duration necessary for a current twice the intensity of rheobase to cause tissue excitation?

What type of feeling is this?

A

Chronaxie

“Strong but comfortable”

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33
Q

What is the main difference between excitable vs non-excitable tissue?

A

Excitable cells have voltage-gates sodium ion channels.

34
Q

What type of muscle strain would result in a negative electrical potential of the tissue?

A

Compressive

35
Q

What type of muscle strain would result in a positive electrical potential of the tissue?

A

Distraction

36
Q

What does Wolff’s Law state?

A

That the tissues of the body will make adaptations when a stress is placed on it.

37
Q

What part of the nervous system tends to have a positive charge?

A

The CNS (positive = proximal)

38
Q

What part of the nervous system tends to have a negative charge?

A

The PNS (negative = distal)

39
Q

True of False:

The current always present in neural tissue but the direction and amplitude depends on the CNS activity.

A

True

40
Q

What is a current of injury produced by?

What does the current do?

A

Any type of cellular trauma; plays a key role in stimulating healing and tissue.

41
Q

What are the measurements of the current of injury? (Before injury, immediately after injury, during healing, and returning to baseline)

A

Before: -10mV
Immediately after: +20mV
During healing: -30mV
Return to baseline: -10mV

42
Q

True or False:
E-stim can cause extracellular molecules to lock into receptor sites on the cell membrane that activate the action system within the cell.

A

True. E-stim of the accurate frequency can activate this response of the cell. The appropriate electrical signal can also create specific sites for enzymes to accelerate cell activity.

43
Q

What type of current do cells seem to respond to?

A

A steady DC current–the cells either move or grow towards one pole and away from the other pole. This can help the healing process and cellular activity.

44
Q

What is the frequency window?

A

Cells may respond only to certain frequencies. Small amplitude DC currents are intrinsic to the ways the body works to grow and repair. So by duplicating these currents in the frequency window, we can hopefully stimulate the right responses from the cells.

45
Q

What is tissue impedance?

A

The resistance of the tissue to the passage of electrical current.

46
Q

What is current density?
Where is it highest at?
Where is it lowest at?

A

Current per cubic area.
Under the electrodes in the skin.
In deep tissues.

47
Q

Which electrode placement has high current density superficially? What placement has high current density in deep tissues such as nerves and muscles?

A

Electrodes placed closely together;

Electrodes placed farther apart.

48
Q

True or False:

Electrodes of equal size do not have equivalent current density under the electrode?

A

False–electrodes of different sizes will cause the smaller electrode to have a greater current density.

49
Q

When trying to match the bioelectric field of the body, where should the negative electrode (cathode) be placed in regards to the positive electrode (anode)?

A

Distally

50
Q

The cathode should be the active electrode when the goal of treatment is this:

A

Contraction of muscular tissue–the negative current will be able to more easily create depolarization of the tissue.

51
Q

What is it called when the summation of muscular contractions increases so much that there is no time for the muscle to relax in between twitches, thus causing the muscle to be in full contraction?

A

Tetany

52
Q

A higher frequency can be used to gain a stronger muscular contraction. What would a lower frequency be used to make?

A

A pumping effect

53
Q

What is the primary difference between an electrically stimulated muscle contraction (e-stim) or a CNS stimulated contraction?

A

The e-stim will stimulate the same muscle fibers every time leading to increased fatigue in those specific fibers (not the entire muscle).

54
Q

Increasing the intensity of the electric current would do what?

A

Increase the penetration. This is why high volt machines can reach a greater depth than low volt machines. However, greater intensities can possible lead to electric pain.

55
Q

If you increase the duration of the current, the intensity will be available for a longer period of time. This means:

A

That the contractile response will be increased because the tissue will be exposed to the stimulus for a longer period of time.

56
Q

What type of current is used to push and pull ions over the electric field?

A

Galvanic–Monophasic (DC) current. This may enhance the movement of charged proteins into the lymph channels.

57
Q 
What are the parameters to control edema with e-stim?
Current:
Intensity:
Frequency:
Pulse duration:
Treatment time:
A 
Low-volt monophasic current
High intensity but without muscular contraction
120pps frequency
Pulse duration as short as possible
30 minute treatment time to continuous
58
Q

True or False:

Edema that is already present can be treated effectively with e-stim.

A

False. However, e-stim can help prevent or decrease swelling if applied immediately after the injury (1/2 hour or so).

59
Q

What fibers are evoked in the gate system of pain control?

A

Peripheral large-diameter A beta sensory fibers

60
Q

What does the gate system do? What unit tends to be used to achieve this?

A

Activates inhibitory interneurons in the spinal cord. This prevents the pain signals from traveling to the brain. A TENS unit can be used to achieve this.

61
Q

What is involved in descending pain control?

A

Serotonin is released by the CNS and synapses with enkephalin receptors to supress substance P.

62
Q

In order to activate the opiate system, what should the current, intensity, frequency, and pulse duration be set to?

A

Current: HVP
Intensity: High (somewhat uncomfortable)
Frequency: Low
Pulse duration: High

63
Q

What chronic pain fibers release substance P? What else can these fibers release when stimulated?

A

A and C fibers; endorphins (opiates).

64
Q

What are the three different ways in which TENS controls pain?

A

Sensory (acute pain), motor (chronic), and brief intense (for pain prior to exercise).

65
Q

What mechanism controls pain during the sensory TENS?

A

Gate system.

66
Q

What mechanism controls pain during motor TENS?

A

Central biasing and opiate-endorphin systems.

67
Q

What mechanism controls pain during brief, intense TENS?

A

Opiate-enkephalin system.

68
Q

Contraindications of TENS (x3):

A

Pregnancy (over lower abdominal & pelvic areas), over the neck, and over the heart.

69
Q

Dangers/Precautions of TENS:

A

Pacemaker, electronic implants, skin allergic reactions, mental confusion, and lack of skin sensation.

70
Q

What occurs when two currents interfere with each other but are in phase with one another are said to be summative (increasing amplitude)?

A

Constructive interference.

71
Q

What occurs when two currents opposing one another and have their waves cancel out?

A

Destructive interference.

72
Q

What is the name of the shape that interference between waves will create?

A

A heterodyne (clover bud).

73
Q

The main differences between premod and IFC?

A

Premod has two electrodes, IFC has four.

Premod’s interference occurs within the machine and IFC’s interference occurs outside the machine.

74
Q

What are the indications for interferential current? (x5)

A

Acute pain control, chronic pan control, muscle spasm, bone healing, and edema control.

75
Q

What is the stereodynamic interferential method?

A

Three interferential currents are used and produce a star-shaped three-dimensional electric field (with 6 electrodes).

76
Q

What component of interferential currents allows the clinican to move the focus of the current around the heterodyne? (Hint: we use it as “target”)

A

Interferential vector scan.

77
Q

What are the contraindications for interferential and premod? (x8)

A

Pregnancy, neck area, chest area, head area, electronic implants, blood clot(s), malignancy, and hemorrhagic area.

78
Q

What kind of stim can possibly be used for edema control (even though it hasn’t been proven well clinically)?

A

Galvanic (because it can push and pull the proteins into the lymphatic system).

79
Q

MENS stands for:

A

Microcurrent electrical neuromuscular stimulators.

80
Q

How should the electrodes for low-intensity stimulators be placed?

A

The negative electrode is placed over the wound or fracture and the second is placed farther away depending on desired depth.

81
Q

What are the three contraincidations for low-intensity stimulators?

A

Neoplastic lesions, osteomyelitis, and electronic implants.

82
Q

In medical galvanism, what reaction should be around the positive pole and what reaction should be around the negative pole?

A

Acid reaction around (+) pole

Alkaline reaction around (-) pole

Physical Agents (13 decks)

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