Unit 2 Lecture Flashcards
specific heat
the amount of energy needed to raise the temp of a material by a given number of degrees
materials with a HIGH specific heat take more energy to achieve _____________________________?
the same temp increase than materials with a LOW specific heat
when both materials are at the same temperature, which type (high specific heat or low specific heat) holds more energy?
materials with a high specific heat
what is the specific heat order of the discussed materials from high to low?
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1 water
2 skin
3 muscle
4 human body
5 fat
6 bone
7 air
name the modes of heat transfer
- conduction
- convection
- conversion
- radiation
- evaporation
describe conduction
- energy exchange by DIRECT COLLISION between 2 materials at different temperatures that continues until materials are at the same temperature
surrounding tissues will always heat
what does the rate of heat transfer by conduction depend on?
- TEMPERATURE DIFFERENCE BETWEEN MATERIALS the greater the temp, the faster the rate
- AREA OF CONTACT - the larger the area, the greater the total heat transfer (but rate of temp rise decreases in proportion to tissue thickness)
- THERMAL CONDUCTIVITY - materials with high thermal conductivity transfer heat faster than those with low conductivity
what is the order of materials’ thermal conductivity from high to low?
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1 silver
2 aluminum
3 ice
4 water at 20 degrees C
5 bone
6 muscle
7 fat
8 air at 0 degrees C
which physical agents are associated with conduction?
hot pack
cold pack
paraffin
describe convection
occurs because of direct contact between a CIRCULATING MEDIUM and another material of a different temp * the thermal agent is in motion*
what physical agents are associated with convection?
whirlpools
fluidotherapy
describe conversion
- heat transfer by a NON-THERMAL form of energy into heat/direct contact not needed, but intervening material (ex-US gel) has to be a good transmitter of energy being used
not affected by temp of thermal agent - depends on the power of the energy source - the temperature between the medium and patient may be the same
rate of temperature tissue increase by conversion depends on
- size of area being treated
- size of applicator
- efficiency of transmission of applicator
- type of tissue being treated (superficial or deep)
which physical agent is associated with conversion?
ultrasound (vibration and sound waves)
describe radiation
direct transfer of energy from a material with a higher temp to one with a lower temp no need for contact or an intervening medium
rate of temperature increase by radiation depends on
- intensity of radiation
- size of area or radiation source
- distance of source from treatment area
- angle of radiation to tissue
what physical agent is associated with radiation?
infrared lamp
describe evaporation
a material must absorb energy to evaporate and change from a liquid to a gas/vapor - absorbed in the form of heat which leads to a decrease in temperature
what are the effects of cold?
- hemodynamic
- neuromuscular
- metabolic
describe the hemodynamic effects of cold (2)
1) INITIAL VASOCONSTRICTION - cooling the tissue decreases the production and release of vasodilators (histamine and prostaglandins) which causes vasoconstriction, blood viscosity, and reduced edema, pain, and fever APPLICATION MUST BE LIMITED TO LESS THAN 15-20 MINUTES
2) LATER INCREASE IN BLOOD FLOW - when cold is applied for long periods of time, or when tissue is less than 50 degrees F, cold induced vasodilation may occur
what is Hunting Response?
when tissue temperature causes an alternation between vasoconstriction and vasodilation (most common in distal extremities, so limit application here to 15 minutes or less)
describe the neuromuscular effects of cold (5)
1) DECREASED NCV - decrease in proportion to degrees and the duration of temperature change (examples: ⬇️ after 5 minutes of cooling & return to normal after 15 minutes///// ⬇️ after 20 minutes of cooling & return to normal after 30 minutes)
2) INCREASED PAIN THRESHOLD - stimulation of the cold receptors could provide enough stimulation to fully or partially block pain sensation and increase threshold by pain-gating (causes edema reduction, interruption of pain-spasm-pain cycle, and decreases blood flow to area)
3) ALTERED MUSCLE STRENGTH - increase or decrease depending on duration of intervention and when it’s measured (measure before cold and in the same format each time for best results) *examples - 5mins of cooling = increased isometric strength/////30mins of cooling = decreased isometric strength at first, then an increase 1 hour later that lasts for 3+ hours
4) DECREASED SPASTICITY - temporary prolonged cooling (up to 30 mins) causes a decrease in afferent spindles and GTO activity that lasts 60-90mins
5) FACILITATION OF MUSCLE CONTRACTION - brief application may facilitate a muscle contraction in a flaccid muscle (effort is short-lived)
describe the metabolic effect of cold
cold decreases the rate of all metabolic rates, including those involved in inflammation and healing (recommended to treat inflammatory joint diseases)
name the uses of cryotherapy
- inflammation control
- edema control
- pain control
- modification of spasticity
- symptom management of MS
- facilitation
describe inflammation control (cold)
- decreases pain by decreasing activity of A-Delta’s
- decreases edema by slowing the rate of fluid traveling from the capillaries to the issues
- decreases redness, heat, loss of function
- reduces bleeding by increasing blood viscosity
- can use after exercise to reduced Delayed Onset Of Muscle Soreness (DOMS)
describe edema control (cold)
- vasoconstriction
- increased blood viscosity
- decreased release of histamine
*when applied as soon as possible with PRICE (Protect, Rest, Ice, Compression, Elevation)
describe pain control (cold)
- 10-15mins of application controls pain for 1+ hour(s)
- blocks A-Delta’s/use of pain-gating by stimulating thermal receptors
- decreases muscle spasms by decreasing pain-spasm-pain cycle
- reduces inflammation = reduces pain
describe modification of spasticity (cold)
- decreases in patients with Upper Motor Neuron (UMN) disorders
- brief applications (5mins or less) decrease Deep Tendon Reflex (DTR) almost immediately
- applications for 10-30mins decrease or eliminate clonus and resistance to passive stretching
describe symptom management in MS (cold)
- HEAT EXACERBATES SYMPTOMS!!
- use cooling vests
describe facilitation (cold)
- rapid application (quick icing) to facilitate motor response in a flaccid muscle
not commonly used and may yield unreliable results
cryokinetics
1) cooling to a point of numbness shortly after an injury for up to 20mins
2) exercise for 3-5mins until sensation returns
3) re-cool to point of analgesia
4) repeat 5 times
used with athletes
cryostretch
cooling agent applied, then stretching - allows for improved stretch, decrease in muscle spasm, and increases ROM