Thermal Agents

Question 1

Whole body stimulus
Response
Goal

Answer 1

Reflex response

Goal is to maintain core temp

Question 2

Local Stimulus
Response
Goal

Answer 2

Localized response

Goal is tissue prevention

Question 3

Heat relies on

Answer 3

Temperature gradients

Heat travels down a temp gradient

Question 4

Mechanisms of heat transfer - Metabolic Rate

Answer 4

way of generating heat
90kcal/hr at rest
>900 with max exercise

Question 5

Mechanisms of heat transfer - Radiation

Answer 5

Infra-red emission to, or from the body

Solar and thermal (photons) radiation

Question 6

Mechanisms of heat transfer - Conduction

Answer 6

Transfer of heat by direct contact
Minor contributor of heat exchange in air
26x greater in water

Question 7

Mechanisms of heat transfer - Convection

Answer 7

Transfer of heat from the skin surface to a moving liquid or gas - air temp is lower than skin will lose heat due to convection

Question 8

Mechanisms of heat transfer - Evaporation

Answer 8

Heat lost with water conversion from liquid to vapor

Question 9

Skin Vasculature

Answer 9

Upper and lower plexus
Papillary loops have large SA - good for heat exchange
Arterioles are highly innervated with sympathetic nerves to regulate BF
Veins achieve max compliance, low blood velocity

Question 10

Whole Body Response

Answer 10

VC = cold
VD = hot
Heat loss = heat gain
Temp Homeostasis at 37 degrees C

Question 11

Thermoregulatory zone

Answer 11

35-41 C

Question 12

Heat from muscle to core via

Answer 12

convection of blood going through it (liquid that is moving)

Question 13

Core and periphery uses what mechanism

Answer 13

Convection is a big one

Question 14

Power of convection

Answer 14

Not just moving air or water

Very little heat transfer btw tissues by conduction

Question 15

Convection and Skin blood flow

Answer 15

Controls dry hear loss in the cold (the more skin BF, the more heat loss you will have)
Works in tandem with sweat in the heat - tendency of SKBF to warm skin is balanced by tendency of sweat evaporation to cool skin
If no inc in flow, cant lose heat (elderly)

Question 16

COuntercurrent Heat exchange

Answer 16

Heat exchange occurs where arterial blood warms venous blood returning to the body
Advantage is that it minimizes impact on core temp

Question 17

Homeotherms maintain…

Answer 17

a constant core temp, NOT a constant blood temp

Question 18

Receptors for whole body skin response - Cold Exposure

Answer 18

Alpha adrenergic receptors with NE (60%)
Unknown cotransmitter (40%)

Question 19

Receptors for whole body skin response - Heat exposure

Answer 19

Muscarinic receptors with Ach (70%)
Unknown cotransmitter (30%)

Question 20

Acral (Glabrous) Skin

Answer 20

Palms, soles of feet, lips, ears
Has arteriovenous anastamoses
- bypass of papillary loop
- deeper, less SA (less effective at heat exchange)
- involved in CIVD (hunting response)
- involved in Raynauds

Question 21

Nonacral (nonglabrous) skin

Answer 21

All other areas of skin (hairy skin)

Question 22

Cold Induced VD

Answer 22

Only present where there is AVAs

Does NOT occur in Raynauds

Question 23

Why Cold Induced VD good

Answer 23

Good because minimze risk of cold injury and inc finger dexterity and is trainable

Question 24

Why COld Induced VD Bad

Answer 24

Bad because dec VC and heat retention

Question 25

Mechanism for Cold Induced VD

Answer 25

Mechanism = synaptic transmission is interrupted

Question 26

What innervates skin - Motor

Answer 26

Autonomic - Sympathetic (dual innervation) Adrenergic Cholinergic (only in nonglabrous)

Question 27

What innervates skin - Sensory

Answer 27

``` From small unmyelinated nerve fibers to large unmyelinated C fibers A delta A beta A alpha ```

Question 28

C fibers

Answer 28

Mechanical stimulation, crude touch, slow pain, and temp warm

Question 29

A delta

Answer 29

sharp pain, inflammation, pressure, temp cold

Question 30

A beta

Answer 30

touch, hair

Question 31

A alpha

Answer 31

deep touch, pressure

Question 32

Normal temp and what temps lead to pain

Answer 32

Normal = 34 C | 15 or 45 - pain

Question 33

Local Responses to Hear Mediated by

Answer 33

Axon Reflex - flare response NO - plateau Vasoconstrictor nerves die away

Question 34

Axon Reflex

Answer 34

Mediated by warm sensitive afferent nerve antidromatic release CGRP, sub P Associated with inflammatory response Occurs naturally with local heating

Question 35

Application of heating agent - Superficial Heat

Answer 35

Does not affect deep tissues Ex = whirlpool, heat pack, infrared heat lamp Modality affects mechanism of transfer Dilated cutaneous vessels transfer heat to core - dissipates heat faster Deep tissues also VD Renetention of heat in skin/fat

Question 36

Application of heating agent - deep heat

Answer 36

Do increase deep tissue temp | Ex = ultrasound, diathermy

Question 37

Local Response to cold - Mediated by

Answer 37

Inhibition of NO Inc in Alpha 2c adrenergic receptors available COld sensitive afferent (antidromatic release)

Question 38

Raynauds Phenomenon

Answer 38

Pallor - cyanosis - rubor and swelling and paresthesia Mechanism - excess alpha 2c adrenergic receptors, stress, caffeine, smoking Tx - calcium channel blocker

Question 39

Application of Cooling Agent - SUperfifical cold

Answer 39

Affects both surface and deep tissues Surface cools faster/more than deeper tissue Temp vs. duration - asymptomatic curve Rewarming takes longer than cooling (more insulation and less BF) Localised applied region Dec intra articular temp

Question 40

Tissue injury can occur from applying thermal agents how

Answer 40

local temp over 42-44 or less than 15 will cause burn

Question 41

What to look for with tissue injury

Answer 41

``` Redness Itchiness Pain Swelling/edema Unusual coloring Blistering ```

Question 42

What to consider when applying thermal agents

Answer 42

``` insensitivity to pain or temp Tissue thickness Raynauds Peripheral Vascular Disease Pregnancy ```

Question 43

How long apply thermal agens

Answer 43

20 min (30 min nma)

Question 44

Neuromuscular effects - cold

Answer 44

Dec conduction velocity Dec spasticity and spasm Dec pain Dec muscular force production

Question 45

Neuromuscular effects - heat

Answer 45

Inc conduction velocity Dec spasticity and spasm Dec pain