Thermoregulation

Question 1

What is the role of skin

Answer 1

More dilation and more flow at superficial area

Carry it to peripheral to cool you down

Question 2

Heat loss =

Answer 2

heat gain

Question 3

Core Temp

Answer 3

37 C or 98.6 F
Abdominal, thoracic, cranial cavities
Measured orally, esophageal, rectal, tympanic mem, pill

Question 4

Skin Temp

Answer 4

34 C
Measured by weighted sum from different regions of the body
We adjust this to maintain core temp

Question 5

Body temp is combo

Answer 5

of skin and core temp

Question 6

Clinically significant core temp

Answer 6

above 38.5 will see symptoms

athletes can get to 40 and feel just fine though

Question 7

Clinically significant skin temp

Answer 7

around 45

Question 8

Heat Stroke

Answer 8

Core temp - 40.5

Question 9

Heat exhaustion

Answer 9

Core temp 38.5 - 39.5

Question 10

Mechanisms of heat gain and loss

Answer 10

Metabolic Rate
Radiation
Conduction
Convection
Evaporation

Question 11

Metabolic Rate

Answer 11

ONLY heat gain
Shivering to warm you up
The higher it is, the higher the heat gain

Question 12

Radiation ***

Answer 12

Heat gain from sun

Heat loss sitting in classroom (we radiate to the environment)

Question 13

Conduction

Answer 13

Through direct contact
Heat gain if touch heater
Heat loss if sit on cold seat

Question 14

Convection ***

Answer 14

Heat gain or loss but from skin surface to a moving liquid or gas
Ex: fan behind the heater

Question 15

Evaporation

Answer 15

Heat loss ONLY

water conversion from liquid to vapor

Question 16

Evaporation requires

Answer 16

vapor pressure gradient

Question 17

Sweating ____ result in heat loss, evaporation must occur - depends on

Answer 17

does NOT
SA exposed
Wind speed
Relative humidity (primary factor)

Question 18

Inability to lose heat by evaporation results in

Answer 18

higher core temp

higher sweat rate

Question 19

How is body temp sensed

Answer 19

Central thermoreceptors - located in POAH, sensitive to heat
Peripheral thermoreceptors - sensitive to cold
Hypothalamus has a set point (POAH) - will cause sweat glands to secrete when core temp inc

Question 20

Effector Response - Cold

Answer 20

VC
Piloerection
Shivering
Non shivering –> thyroxin release

Question 21

Effector Response - Heat

Answer 21

VD

Sweating an evaporation

Question 22

Reflex to cold

Answer 22

Peripheral thermoreceptors –> adrenergic –> NE –> VC

Question 23

Reflex to heat

Answer 23

Central thermoreceptors –> cholinergic –> Ach –> VD

Question 24

Neural control of Cutaneous innervation

Answer 24

Dual sympathetic innervation
Adrenergic = VC
Cholinergic = VD

Question 25

At rest what tone is on muscle

Answer 25

adrenergic have some tone on muscle so when you get hot, you withdraw the symp adrenergic tone and that causes passive dilation that doubles flow and then you activate cholinergic that causes huge (6 fold) inc in flow and cholinergic is also stimulating sweat response to cool you down

Question 26

Distribution of CO when hot

Answer 26

CO will Inc. (SV dec and HR Inc) | When hot, there is a lot going to the skin

Question 27

Submaximal exercise in the heat for absolute workload CO - what will decrease

Answer 27

``` CO SV MAP Central blood volume (most in skin) TPR ```

Question 28

Submaximal exercise in the heat for absolute workload CO - what will increase

Answer 28

avO2 difference Rectal temp HR

Question 29

Exercise + Heat + Dehydration and muscle blood flow

Answer 29

SV may decrease to maintain CO Inactive tissue compensates (splanchnic) Skin is next Active muscle will eventually help compensate

Question 30

Other systems at work during exercise

Answer 30

Angiotensin II --> VC --> Inc BP Angiotensin II stimulates thirst centers Aldosterone stimules sodium reabsoprtion

Question 31

Why is hydration state important during exercise

Answer 31

poorly hydrated athlete can't perform at his/her peak

Question 32

When we get thirsty..

Answer 32

Already dehydrated - dehydration preceeds thirst | 2% of body weight dehydrated before feeling thirsty --> decline in performance

Question 33

What happens when athletes are dehydrated

Answer 33

``` Blood volume shrinks Skin blood flow is less Muscle blood flow is less Temperature rises Fatigue Blood Pressure Dec Lightheaded Syncope Hyperthermia ```

Question 34

What makes athletes drink more fluids

Answer 34

inc by 45% when flavoring is added to water | Additional inc by 46% when flavor contained NaCl

Question 35

Dehydration imposes

Answer 35

Thermal and CV stress

Question 36

Heat Cramps

Answer 36

Associated with Na, K losses | Pulls water from cells to ISF

Question 37

Heat Exhaustion

Answer 37

Dizziness, extreme fatigue, vomiting, faintain, tachycardia, hypotension, profuse sweating Volume loss that is more than high core temp Treat with cooling, fluid and electrolyte replacement

Question 38

Heat Stoke

Answer 38

Rising core temp, cessation of sweating, hot and dry skin, hypotension, confusion or unconsiousness Treatment = immediate rapid cooling - ice immersion

Question 39

Preventing Heat Injury

Answer 39

Plan events when environmental conditions are best Recognize symptoms Water availability Acclimation

Question 40

Heat Acclimization

Answer 40

After known history of heat illness, acclimation is most important predictor of heat tolerance

Question 41

Most critical component in heat acclimation

Answer 41

expansion of plasma volume