PHYSIOLOGIC RESPONSES TO ELECTRICAL CURRENT

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PHYSIOLOGIC RESPONSES TO ELECTRICAL CURRENT

• Veronica Southard PT MS GCS

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What are the effects of current?

• 1. Thermal. There is a minimal amount of
  increased temperature in conducting tissue
• 2. Chemical. Usually long duration continuous
  D/C.

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Polar effects

• Pole
• Acid reaction
• Coagulation of Proteins
• Hardening of tissues

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Polar effects

• - Pole
• Alkaline reaction
• Protein liquification
• Softening of tissues
• More caustic to skin
• Increased nerve excitability
• Good for chronic painrelief

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Safety

• Be sure to use a grounded plug
• Check for fraying

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Electrical Stimulating Currents

• In general, the current selected is based on the
  knowledge of its affects on biology
• A careful examination is always necessary first
• Keep in mind that electricity affects the tissue
  as it passes through

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Purpose of using current

• 1. Cause m contraction
• 2. Stimulate sensory n for pain reduction
• 3. Create an electric field for healing biologic
  tissue
• 4. Create an electric field on skin surface to
  drive ions of medication in

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Electricity creates changes in physiologic
functioning at 4 levels

• 1. Cellular
• 2. Tissue
• 3. Segmental
• 4. Systemic

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I. Cellular

• Excitation of n cells
• Changes in cell membrane permeability
• Pr- systhesis
• Stimulates fibroblast, osteoblast activity
• Modification of microcirculation

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II. Tissue

• Requires multiple cellular events
• Skeletal m contraction
• Smooth m contraction
• Tissue regeneration

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III. Segmental

• Requires effects at cellular and tissue levels
• Modification of level of jt. Mobility
• Muscle pumping
• Altered microvascular systems not affected by m
  pumping
• Increased movement of charged Pr- into Lymphatic
  channels
• Sensory stimulation

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IV.Systemic Effects

• Analgesia
• Endogenous release
• Stimulation of certain neurotransmitters

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Effects

• Direct occur along the circuit
• Indirect remote to treatment area

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Muscle and Nerve Responses to Electrical Current

• Based upon the voltage sensitive permeability.
• Nerve or Muscle cells regulate the interchange of
  substances between the inside of the cell and its
  external environment
• There is an unequal distribution of charged ions
  that creates a potential difference or gradient.
• The gradient causes the membrane to be polarized

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Action Potential

• To occur there must be excitation to stimuli
  created by electrical, thermal, mechanical or
  chemical stimuli
• Caused by a change in the gradient, so that the
  resting potential moves toward a direction
• Excitation of the m cell or nerve axon(AP)

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Sequence of events in an AP
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Impulse propagation

• Orthodromic
• Antidromic

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Depolarization with Electrodes in Place

• Cathode usually the active electrode and site of
  depolarization. As the concentration of cations
  increases the membranes voltage potential moves
  in a positive direction and is brought to
  threshold
• The anode or indiferent electrode, makes the
  nerve cell membrane potential ////

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Current flow

• Current flows from the depolarized region through
  the intercellular material to the inactive
  membrane. The current also flows through the
  extracellular material back to the depolarized
  area, and finally into the cell again