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Understanding Thermoregulation: Body Temperature and Dehydration in Physical Activity, Quizzes of Physical Education and Motor Learning

The concept of thermoregulation, the body's response to maintain a normal temperature. It covers the diurnal fluctuations of body temperature, contributing factors to heat gain and loss, the thermal balance equation, core temperature during physical activity, consequences of dehydration, and factors affecting sweat-loss dehydration. The document also discusses water replacement and rehydration, acclimatization, and thermoregulatory differences in various populations.

Typology: Quizzes

2015/2016

Uploaded on 12/11/2016

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TERM 1
Thermoregulation
DEFINITION 1
Normal body temperature fluctuates several degrees during
the day in response to physical activity, emotions, and
ambient temperature variations.Body temperature exhibits
diurnal fluctuations:
Lowest temperatures occur during sleep.
Slightly higher temperatures persist awake.
TERM 2
Contributing factors to heat gain and loss to
regulate core temperature at
DEFINITION 2
98.6F (37C).
TERM 3
Thermal Balance Equation
DEFINITION 3
+M-E+/-TR+/-CD+/CV+SRWhere:M = MetabolismE =
EvaporationTR = Thermal RadiationCD = ConductionCV =
ConvectionSR = Solar Radiation
TERM 4
Core Temperature During Physical Activity
DEFINITION 4
Heat generated by active muscles i ncrease core temp to fever
levels that incapacitate a person if c aused by external heat
stress alone.
Increased core temp with PA does n ot reflect heat dissipation
failure.
Modest core temperature increase reflects favorable internal
adjustments that create optimal the rmal conditions for
physiologic and metabolic function
TERM 5
Intense PA for 2 to 3 hrs can induce
dehydration
DEFINITION 5
Can impede heat dissipation and compromise CV function
and performanceAverage water loss per hour from sweating
at various air temp during rest and light and moderate PA
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Thermoregulation

Normal body temperature fluctuates several degrees during the day in response to physical activity, emotions, and ambient temperature variations.Body temperature exhibits diurnal fluctuations: Lowest temperatures occur during sleep. Slightly higher temperatures persist awake. TERM 2

Contributing factors to heat gain and loss to

regulate core temperature at

DEFINITION 2 98.6F (37C). TERM 3

Thermal Balance Equation

DEFINITION 3 +M-E+/-TR+/-CD+/CV+SRWhere:M = MetabolismE = EvaporationTR = Thermal RadiationCD = ConductionCV = ConvectionSR = Solar Radiation TERM 4

Core Temperature During Physical Activity

DEFINITION 4 Heat generated by active muscles increase core temp to fever levels that incapacitate a person if caused by external heat stress alone. Increased core temp with PA does not reflect heat dissipation failure. Modest core temperature increase reflects favorable internal adjustments that create optimal thermal conditions for physiologic and metabolic function TERM 5

Intense PA for 2 to 3 hrs can induce

dehydration

DEFINITION 5 Can impede heat dissipation and compromise CV function and performanceAverage water loss per hour from sweating at various air temp during rest and light and moderate PA

Fluid Loss in Physical Activity

For acclimatized person, sweat loss peaks at 3 Lh1 during intense PA in heat and averages nearly 12 L/d. Intense sweating for several hr induces sweat gland fatigue that impairs core temp regulation. Hot, humid environ impede effectiveness of evaporative cooling and promotes large fluid losses TERM 7

Consequences of Dehydration

DEFINITION 7 Any dehydration impairs physiologic function and thermoregulation.Plasma volume decreases as dehydration progresses: Peripheral blood flow and sweating rate decrease to make thermoregulation more difficult. Premature fatigue occurs from reduced plasma volume that increases HR, RPE, core temp. Loss of plasma volume produces two effects: Initiates increases in systemic vascular resistance Reduces skin blood flow TERM 8

Factors That Affect Sweat-Loss Dehydration

DEFINITION 8 PA intensityPA durationEnvironmental tempSolar loadWind speedRelative humidityClothingWater Requirements (LH1) for rest and varying intensities of PA in the heat; indoors and outdoors at diverse temperatures and RH. TERM 9

Water Replacement and Rehydration

DEFINITION 9 Adequate fluid replacement sustains evaporative cooling of acclimatized humans. Proper scheduling of fluid replacement maintains plasma volume for optimal circulation and sweating progress. Well-hydrated athletes always function at a higher physiologic and performance level than dehydrated athletes. TERM 10

Acclimatization

DEFINITION 10 Repeated heat exposure with PA improves capacity for PA with less discomfort; optimal acclimatization requires adequate hydration.

Existing Age-Related Thermoregulatory

Differences: Children

Prepubescent children show lower sweating rate and higher core temperature during heat stress.Children take longer to heat acclimatize.Children exposed to environmental heat stress should exercise at a reduced intensity and receive additional time to acclimatize. TERM 17

Gender and Thermoregulation

DEFINITION 17 Women and men equally tolerate physiologic and thermal stress of PA when matched for fitness and acclimatization levels. Gender differences occur for four thermoregulatory mechanisms: Sweating Evaporative versus circulatory cooling Body surface area-to-mass ratio Menstruation TERM 18

Excess body fat

DEFINITION 18 Excess body fat negatively impacts performance in hot environments. Fats specific heat exceeds that of muscle tissue to insulate the bodys shell to retard peripheral heat conduction. Large overfat persons possess a smaller body surface area-to- mass ratio for sweat evaporation compared with leaner, smaller persons. Excess body fat directly adds to energy expended in weight- bearing activities. TERM 19

Cold Weather Physical Activity

DEFINITION 19 Human exposure to extreme cold produces considerable physiologic and psychologic challenges.Cold ranks high among the differing terrestrial environmental stressors for its potentially lethal consequences. Body loses heat 2 to 4 faster in cool water compared with air at the same temperature. Metabolic heat generated by muscular activity contributes to thermoregulation during cold stress. Individual differences in body fat content significantly effects physiologic function in a cold environment during rest and PA. TERM 20

Five factors compromise core temperature

regulation in the cold

DEFINITION 20 Chronic exertional fatigue Sleep loss Inadequate nourishment Reduced tissue insulation Depressed shivering heat production

Acclimatization to Cold

Humans adapt more poorly to chronic cold exposure than heat exposure. Increased heat production does not accompany body heat loss; individuals regulate at a lower core temperature in the cold. Repeated cold exposure of hands or feet brings about blood flow increases through these anatomic regions during cold stress. TERM 22

Early warning signs of cold injury include:

DEFINITION 22 Tingling and numbness in fingers and toes Burning sensation in nose and ears Disregarding signs of overexposure leads to frostbite