Electricity and Light

Examples of excitable tissue

Muscles, cell membrane and nerves

How electrical current flows through the body

Must have a pump (driving force)

Must have positive and negative polarization

Electricity stimulates motor units or sensory nerves. Gives it enough power until it reaches the nerves threshold which stimulates the action potential causing muscle contractions

Quantum theory of light definition

Light exists in photons, which each has a definite amount of energy

Light has no mass and therefore it cannot be stopped and measured at a particular point

Example of conductors

Metals

Loosely bound electrons

What the intensity of electromagnetic waves reaching the body is dependent on

the energy output from the source, the distance from the patient (inverse law), and the angle of incidence (cosine law)

Examples of waves that are on the electromagnetic spectrum

X-ray, visible light, non-visible light, microwaves and UV light from the sun, radio, Gamma

Direct current

Continuous unidirectional flow or charged particles

Charge of current stays either positive or negative the whole time

Commonly used for iontophoresis, meds charge is the same as machine, causing meds to repel and go deeper into skin

Alternating current

Continuous bidirectional flow of charged particles

Used for pain control and muscle contraction

Pulsed current

Interrupted flow of charged particles

Most common

Used for pain control, tissue healing, and muscle contraction

What type of nerves does Estim have the ability to stimulate?

Sensory nerves (feel good)

Motor nerves (muscle contraction)

Do electromagnetic waves require a medium to travel?

No

Cosine Law

The angle of the incidence of the beam with the tissue (90 degrees)

The effect of the EMR is determines mostly by the frequency and wavelength

Inverse square law

An object twice the distance from the light source will receive a quarter of the amount of illumination

Ohms Law

The relationship between the current, voltage, and resistance.

When putting electricity in the body, some tissue provides resistance and some don’t. Electricity will go to the tissue with the least amount of resistance.

Voltage Law

The sum of the voltage changes around any closed path must add to zero.

Electricity will not be left in the tissue. Whatever energy is gained by the charge from the energy source is used as it completes its path around the circuit.

Examples of ways electromagnetic radiation can affect tissue

High frequency EMS breaks molecular bonds to form ions that can destroy tissue

Hot lasers, X-rays, gamma rays

Used surgically and for imaging

Examples of ionizing radiation

Gamma rays and xrays

In small doses to treat cancer cells

Examples of non-ionizing radiation

Shortwave and microwave radiation

Examples of non excitable tissue

Bone, ligament, tendon, and adipose tissue

Examples of insulators of electricity

Rubber and ceramics

Tightly bound electrons