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Exercise Physiology > Thermoregulation > Flashcards

Thermoregulation Flashcards

1
Q

thermoregulation

A

body’s ability to maintain an internal temperature

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2
Q

Temps for humans

A

although humans can tolerate extremems in environmental temp, a relatively small change in core body temp ~ 4 degrees celcius leads to significant impairment of mental and physical function

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3
Q

core body temperature

A

regulated by hypothalamus, controls involuntary mechanisms that maintain internal temp of 37degrees
hypothalamus is sensitive to small temp changes - 0.1-0.5 degrees

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4
Q

thermal receptors

A

central and peripheral

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5
Q

central thermal receptors

A

hypothalamus and cortex of the brain

- blood perfusing these regions stimulates the receptors

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6
Q

peripheral thermal receptor

A

skin and visceral receptor for cold and warm temps

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7
Q

why does Q drop when youre warm

A

vasodilation for reduction of heat on SA which drives down your BP

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8
Q

a risk of increasing heat

A

not enough perfousion to the brain so you need to elevate their legs

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9
Q

activation of the regulatory centres in the hypothalamus reuslts in

A

thermal effector responses - behavioral, physiological

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10
Q

biological rhythms of thermoregulation

A

wake up

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11
Q

bacteria and virus on thermoregulation

A

immune related but need to protect the proteins in the body

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12
Q

what two hormones regulate the body temp

A

catecholamines and thyroxine

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13
Q

thermal balance

A

body temp is maintained within a narrow range through heat gain and loss

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14
Q

do we gain and lose heat

A

no we get radiated, conducted or convected, then BMR/RMR, thermogenesis, muscular activity, then we evaporate, convect, conduct and radiate

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15
Q

radiation (4)

A

transfer of heat between two objects through electromagnetic heat waves

  • the body loses heat if the surrounding is cooler
  • the body gains radiant heat from the sun
  • represents the majority of the heat less from the body at rest (60%)
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16
Q

conduction (3)

A

transfer of heat between molecules in direct contact

  • application to the skin
  • 3% of the heat loss from the body at rest
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17
Q

convection (4)

A

transfer of heat with the flow of water or air across the skin
- fan blowing over the surface of the skin
12% of heat loss at rest, 20% of heat loss in water and 20% or heat gain in a hot pool

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18
Q

evaporation (6)

A
  • conversion of liquid into vapour
  • 150-340 sweat glands/cm^2
  • 25% of heat loss at rest occurs via unnoticed insensible perspiration skin and respiratory evaporation
  • 99% of sweat is water, 1% electrolyte (Na, K, Cl)
  • major mechanism of heat transfer during exercise
  • evaporation of sweat cools the skin (not sweat by itself), if the sweat is wiped away, the cooling effect is negated
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19
Q

respiratory evaporation

A

breathing out humidation

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20
Q

core temperature

A

36.1-37.8c

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21
Q

rectal temp

A

valid for core temp

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22
Q

esophagus temp

A

lower than rectal temp due to evaporative cooling with breathing

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23
Q

tympanic temp

A

slighly lower than rectal temp

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24
Q

telemetry thermal pills

A

expensive and more challenging to use

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25
Q

skin stemp

A

temp fluctuates under the influence of environmental conditions

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26
Q

heat stress

A

the physical work and environmental components that combine to create heat load on an ind.

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27
Q

factors affecting hyperthermia (4)

A

heat production - BMR, PA
circadian rhythms
age/gender
body size, body fat

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28
Q

5 modulators of hyperthermia

A 
temp, humidity, wind 
hydration status 
fitness 
clothing 
cooling strategies
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29
Q

heat strain

A

acute physiological response and resulting thermoregulatory processes to combat heat stress

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30
Q

physiological response of heat exposure (3)

A

general peripheral dialaion - arteriovenous anastamoses
increased sweating to promote evaportation - compromised by increased humidity (heat stress index)
- 1L of vaporized sweat - 580kcals
increased ventilation (expel heat through lungs)

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31
Q

heat can do two things on exercise performance

A

increase muscle temp without increasing core temp

increase core temp

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32
Q

increasing muscle temp without increasing core temp (2)

A

increased enzyme reacion speed

increased sprint speed

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33
Q

increasing core temp (3)

A

reduce VO2max
impaired submaximal and maximal exercise performance
MVC and repeat spring bouts compromised

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34
Q

heat exposure in sport

A

start training for adaptation to happen, when you compete in the heat with a lower Q, lower blood to uslces and lower drive to exercise

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35
Q

kids and temp

A

increased SA and higher BMR, they dont sweat as much, dissipated through convection and conduction, lower Q, so harder time to get it to the skin

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36
Q

females and temp

A

dont sweat as much and more SA, subcutaneous fat adipose tissue as insulator

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37
Q

Q 10 effect

A

increase temp of enzyme by 1-2 degrees, 5-10% increase in activity

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38
Q

heat reduced VO2max (3)

A

reduced stroke volume
- dilation of vessels reduces TPR leading to decrease in MAP/preload
- decrease in blood plasma volume due to sweating
cardiovascular drift
- HR steadily increases to maintain Q and MAP
reduced utilization of oxygen due to compromised blood flow
- increased anaerobic metabolism

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39
Q

why does HR need to increase to maintain Q

A

because SV is decreased

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40
Q

when hr maxes after heat

A

continue with peripheral resistance or stop vasodilation and increased MAP, but then you accumulate a lot of heat

41
Q

how to increase cycle performance in a tropical climate

A

physical and perceptual cooling with beverage

42
Q

how to trick the receptors

A

keep skin temp decreased so they think its cooler than it is

43
Q

exertional heat illness

A

spectrum of disorders that range in intensity and severity from mild CV and CNS disruptions to severe cell damage, including the brain, kidney and kidney

44
Q

hyperthermia

A

core temp above 41, above 42 can be fatla, above 44, body begins to denature

45
Q

high body temp can lead to

A

breakdown in nerve tissue, local hemorrhage, ultimately organ failure

46
Q

minor exertional heat illness

A

heat cramps and heat syncope

47
Q

heat cramps 2

A

occur in leg, arms, and abdominal muscles after several hours of strenuous exercise in heat
possible cuases - fluid electrolyte imbalance, dehydration, altered neuromuscular control

48
Q

heat syncope

A

pooling of blood in periphery affecting CO and flow of blood to brain

49
Q

seriour exertional heat illness

A

heat exhaustion
heat injury
heat stroke

50
Q

heat exhaustion

A

(38.5-40c) - rapid and weak pulse

51
Q

heat injury

A

hyperthermia accompanied by organ damage (rhabdomyolosis)

52
Q

heat stroke

A

life threatening illness marked by CNS and multiorgan failure

53
Q

goosebumps for heat

A

early sign of severe heat exhaustion - thermoregulation no longer working properly

54
Q

acclimatization

A

adaptive changes that occur when an ind undergoes prolonged or repeated exposure to a stressful environment - for you to become more efficient

55
Q

acclimatization to heat (5)

A

occurs as early as 1-4 days and completed with 10-24 days
increased plasma volume (3-27%
increased sweat distribution
reduced sweat threshold - sweating at lower temp
reduced sweat and urine electrolytes/aldosterone

56
Q

fitness level and acclimatization

A

regular training will result in 50-60% of total physiological adaptation even if training in a cool environment

57
Q

sweating at salt

A

you want to retain a lot more sodium to maintain muscle function - if you’re a heavy salt sweater you need more salt

58
Q

4 cooling strategies

A

precooling/cooling during exercise
clothing
maintain hydration status
reduce warm up time

59
Q

precooling/cooling during exercise

A 
ice vests (keep it on or right after you start take it off), ice packs, mist fans, cold air 
more room
60
Q

clothing for cooling -2

A

light colored clothing and hat to reflect radiative heat

well ventilated, loose fitting shirt to allow for efficient evaporation

61
Q

maintain hydration status

A

monitor weight and urine color

62
Q

epidermal microfluidic biosensor - 4

A

water, lactate, glucose, pH, chloride

63
Q 
when you lose % BW hydration 
2-3
5
7
15
20
A 
affect performance - decrease by 30% 
discomfort and lethargy 
dangerous (salivating stops) 
delirium, shiveled skin 
death
64
Q

during exercise, does voluntary fluid intake fully replace fluid loss?

A

no, gastric emptying rate for water is 600-1200ml/hr

interind variability

65
Q

3 considerations for hydration

A

150-250 ml every 15 mins during events
carbs and sodium in rehudration solution enhance intestinal absorption
temp does not affect absorption, but cool water will help cool the body

66
Q

strength and power for hydration

A

alright

67
Q

exercise associated hyponatermia

A

fluid electrolyte disorder caused by overhydration without adequate electrolyte intake - low blood sodium concetrations (<135mEq/L) leads to swelling in the brain (water into intercellular in brains because brain doesnt lose na) - swelling in brain stem can cause the dorsal ventilatory gp to be pressured

68
Q

symptoms of exercise associated hyponatremia

A

mild - headahce, nausea, cramping

severe - seizure, coma, cardiac arrest - can be fatal

69
Q

environmental factors affecting hypothermia

A

temp - keep up Q
water - 4-5 times faster to take heat away
wind - convection - much faster

70
Q

ind factors affecting hypothermia

A

age - kids have larger SA, dont thermoregulate very well, lose more heat
older - dont vasoconstrict as well
gender - males dissipate more heat because females have insulators

71
Q

insulating factors for hypothermia

A

subcutaneous fat

clothing - cotton - fibre holds wet moisture aginst your skin, not good, wool is better

72
Q

3 acute physiological responses to cold exposure

A

general peripheral vasoconstriction
increased metabolic heat production through - non shivering thermogenesis - increased catecholamine and thyroxine release
- shivering thermogenesis - increased heat with muscle contraction
piloerection “goosebumps - subcutaneous fat mechanism to trap heat

73
Q

what receptors do vasoconstrict

A

alpha 1

74
Q

where do you send heat when youre cold

A

core for steady temp

75
Q

decreased muslce temp without decrease in core temp (3)

A

slightly increased VO2 max (4degrees) - good in endurace sports but not short because of a decrease of enzyme activities
reduced fatigue

76
Q

decreased core temp (3)

A

impaired nerve signaling (sensory and motor
force generation from type 1 muscle fibres impaired, therefore recruitment of type 2 fibres is expedited
strength and power compromised because impaired MU recruitment

77
Q

after drop

A

in a cold environemnt you want to keep the warm blood at your core, but the as soon as he moves he vasodilates and the cold blood comes in

78
Q
  • cold and jerky movements
A

increased utilization of FT fibres for fine motor movements

79
Q

decreased core temp can drop VO2 max -3

A

compromised muscle function (Q10), decreased HR, increase blood viscosity
reduced oxygen unloading from hemoglobin
drop of 5-6% in VO2 max for every 1 degree drop in core body temp

80
Q

increased submaximal vo2 with cold -why and 2

A

increased metabolic rate

  • higher metabolic cost for type 1 which reduces fat utilization (bonking) - more glycogen and run out of energy quicker
  • coactivation of agnist and antagonist muslces
81
Q

overall effect of decreased core temp

A

reduced submax endurance

82
Q

hypothermia

A

core temp less than 35 degrees resulting in the loss of normal function

83
Q

2
4
6
more than 6 drop in core temp

A

mild - max shivering
mod - ataxia, apathy, cognitive impairment (coordinated movements)
severe - unconsciousness
abnormal heart rhythm, decreased brain blood flow, death
usual fatal limit = core between 23-25

84
Q

cold survival story

A

female fell into waterfall while skiing
- 80 min after - core 14.4
-13.7 when warming started
returned to normal function

85
Q

why bring extra layers when you go down the back side of the mountain

A

hypoglycemic and no sun

86
Q

a person is not dead until?

A

they are warm and dead, metabolic processes in your body is slowed so preserved, as long as they still have a heart beat, dont give up until they are warm and dead

87
Q

frostbite

A

consequences of water crystalization within tissues that causes cellular dehydration and leads to tissue destruction, occurs when temp falls below 0

88
Q

can you freeze your lungs

A

no, air that is -40 is humidified and warmted to body temp by the time it reaches the lungs

89
Q

paradoxical undressing

A

towards the end stages of hypothermia ppl start taking clothes off - failure of vasoconstriction and rush out of core blood?

90
Q

terminal burrowing

A

curl up into a tiny place, hypothesized to be instinctive behaviour to preserve heat

91
Q

when does cold acclimatization occur?

A

first 7 days

92
Q

4 effects of cold acclimatization

A

increased non-sivering thermogenesis
- increase in thyroxin and NE
- uncoupling oxidative phosphorylation adipose tissue increases
reduced shivering threshold
hunting reaction - intermittent peripheral vasodilation of the vessels in the hands, feet, and face for increased skin temp
increased subcutaneous fat - swimmers have economy benefits but some have to do dryland to get rid of it

93
Q

eventual step of cold acclimatization

A

habituation to discomfort

94
Q

baby withouth the blanket can still be warm to touch because

A

they have lots of brown adipose tissue

95
Q

4 considerations for cold

A

dress in layers, wicking as first
20-30% heat lost through head/neck
windchill hardest on toes, fingers, nose, ears
enough glycogen store

96
Q

rec outdoor jogging advice for cold

A

first half - run into the wind - not much sweat so no cooling ffect
second half - return with wind at back

97
Q

2 layers winter camping (3)

A

day time - wet clothing because youre generating heat
night - dry clothes for insulation
gortec shell to get rid of

98
Q

should you wear down jakets to exercise

A

no moisture gets in

Exercise Physiology (17 decks)

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