2) 8/24 Ch 1: The Basic Science of Therapeutic Modalities

What does each color represent?

a photon of different energy

Describe Infared.

long wavelengths, low frequency, low energy, goes farther into the body

Describe ultroviolet.

short wavelengths, high frequency, high energy, does not go as deep in the body

The longer the wavelength the _____ penetration. The shorter the wavelength the _____ penetration.

greater; less

Occurs when the wave strikes an object and is bent back away from the skin

reflection

What surface tends to reflect energy?

skin

The deflection of waves because of a change in the speed of absorption as the wave passes between media of different densities.

refraction

What tissue tends to refract waves?

fat

Occurs when the wave passes through a medium and the energy is partially or totally taken in by surrounding tissues.

adbsorption

No changes or reactions can occur in the tissues unless the amount of energy absorbed is sufficient to stimulate the absorbing tissues.

Arndt-Schultz Principle

The energy will travel in a straight line until reflected, refracted, or absorbed.

1 law of Grotthus-Draper

If the energy is not absorbed it must be transmitted to the deeper tissues.

2 law of Grotthus-Draper

The greater the amount absorbed the less transmitted and thus the less penetration.

3 law of Grotthus-Draper

If too much radiation is absorbed by superficial tissues, not enough will absorbed by deeper tissues.

4 law of Grotthus-Draper

If the amount of energy absorbed by the target tissue is enough to stimulate the tissue, physiologic response will occur.

5 law of Grotthus-Draper

The smaller the angle between the propagating radiation and the right angle, the less radiation reflected and the greater the absorption.

Cosine Law

Each time the distance between the energy and the tissue is doubled, the intensity of the energy received by the tissues is reduced by a factor of 4.

Inverse Square Law

What is the rate of heat transfer?

the greater the temperature difference the more rapid changes in temperature causing the increased depth of penetration