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Exercise Physiology > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

normal core body temp

A

37* C

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2
Q

above 45* C core body temp

A

may destroy proteins and enzymes and lead to death

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3
Q

below 34*C core body temp

A

may cause slowed metabolism and arrhythmias

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4
Q

thermal gradient from body core to skin surface

A
  • ideal gradient is 4* C
  • in extreme cold, may be up to 20*
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5
Q

Voluntary Heat Production

A

Exercise
70-80% energy expenditure appears as heat

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6
Q

Involuntary heat production

A

shivering- increases heat production by 5x
non-shivering thermogenesis- action of hormones thyroxine, catecholamines (speed up metabolism)

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7
Q

Radiation

A
  • transfer of heat via infrared rays
  • 60% heat loss at rest
  • can be method of heat gain
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8
Q

Conduction

A

heat loss due to contact with another surface

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9
Q

Convection

A
  • heat transferred to air or water
  • ex: fan pushing air past skin
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10
Q

Evaporation

A

-heat from skin converts water to water vapor

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11
Q

Evaporation rate depends on:

A
  • temperature and relative humidity
  • convective currents around the body
  • amount of skin surface exposed
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11
Q

skin vapor pressure

A

~32 mmHg
(the greater the gradient or difference is the greater heat loss)

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12
Q

% heat loss at rest due to evaporation

A

25%

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13
Q

L of sweat evaporated to kcal heat lost

A

1 L (1000 ml) sweat results in heat loss of 580 kcal
(body loses 0.58 kcal heat/ml sweat evaporated)

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14
Q

Calculation of heat loss via evaporation

A
  • total energy expenditure (min * kcal/min)
  • total heat produced
    (kcal * energy lost as heat)
  • evaporation to prevent heat gain
    (kcal / kcal/L)
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15
Q

Heat produced that is not lost…

A

is stored in body tissues and will raise body temperature

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16
Q

body heat gain during exercise

A

heat produced - heat loss

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17
Q

amount of heat required to raise body temperature

A

specific heat of human body is 0.83 kcal/kg
(heat required to raise body tem 1* C = specific heat * body mass)

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18
Q

Calculation of body temp increase during exercise

A
  • total energy expenditure (min *Kcal/min)
  • total heat produced
  • total heat stored
  • amount of heat storage to increase body temperature by 1*C
  • increase in body temperature during exercise
  • post-exercise body temperature
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19
Q

Preoptic anterior hypothalamus (POAH)

A
  • body’s “thermostat”, maintains around constant core temperature
20
Q

POAH response to increase in core temp

A
  • cutaneous vasodilation, allowing increased heat loss
  • stimulation of sweat glands for evaporative heat loss
21
Q

response to decrease in core temperature

A
  • shivering and increased norepinephrine release
  • decreased skin blood flow via vasoconstriction
22
Q

as temperature and humidity goes up…

A

the body relies on evaporative heat loss more as convective and radiative heat loss become methods for heat gain

23
Q

Heat Index

A

relative humidity added to air temperature, measure of how hot it feels

24
Q

high relative humidity reduces evaporated heat loss

A
  • lowers heat loss
  • increases body temperature
25
Q

exercise in the heat

A
  • reduced ability to lose body heat
  • higher sweat rate, may be as high as 4-5 L/hour, risk of dehydration
26
Q

dehydration and performance

A

dehydration of 1-2% body weight can impair performance

27
Q

hydration guidelines

A
  • hydrate prior to performance
  • consume 150-300 ml fluid every 15-20 min
  • monitor urine color
28
Q

impaired exercise performance in hot environment

A
  • cardiovascular dysfunction: reduced stroke volume, cardiac output, and muscle blood flow
  • accelerated muscle fatigue: increased radical production, decreased muscle pH, muscle glycogen depletion
    -central nervous system dysfunction: decreased motivation, reduced voluntary activation of motor units
29
Q

gender and age heat acclimitization

A

no difference

30
Q

Precooling

A

lowering body temp before exercise in the heat improves exercise performance
combining cooling techniques increases imporvement

31
Q

acclimation

A

rapid adaptation (days to weeks) to environmnetal change

32
Q

acclimatization

A

adaptation over a long time period (weeks to months)

33
Q

acclimation and inactivity

A

acclimation is lost within days of inactivity or no heat exposure
significant decline in 7 days, complete loss in 28 days

34
Q

physiological adaptations during heat acclimation (4)

A
  • 10-12% increase in plasma volume to maintain blood volume, stroke volume, and sweating capacity
  • earlier onset of sweating and higher sweat rate
  • reduced skin blood flow
  • reduced sodium chloride loss in sweat, reduced risk of electrolyte disturbance
35
Q

Heat acclimation and heat shock proteins

A

-heat acclimation reduces the risk of heat injury in response to exposure of heat stress
- protection is due to synthesis of heat shock proteins in cells, protect cells from thermal injury, stabilizing and refolding damaged proteins

36
Q

exercise in vinyl suits

A
  • can promote acclimation
  • risk of hyperthermia
  • not effective for weight loss
36
Q

exercise in cool for heat acclimation

A

it works but less than training in the heat

37
Q

partial pressure

A
  • % of O2, CO2, and N2 in the air is same
  • there is lower partial pressure of O2, CO2, and N2 at higher altitudes
38
Q

atmospheric pressure

A

decreases at higher altitude

38
Q

hypoxia

A

low partial pressure of O2 (at altitude)

39
Q

Normoxia

A

normal PO2 (sea level)

40
Q

Hyperoxia

A

high PO2 (below sea level)

41
Q

Altitude and short term anaerobic performance

A
  • lower PO2 has no effect on performance
  • lower air resistance may improve performance
42
Q

altitude and long term aerobic performance

A
  • lower PO2 results in poorer aerobic performance as it is dependent on oxygen delivery to muscle
43
Q

altitude and VO2 max

A
  • decreased VO2 max at higher altitude due to lower oxygen extraction
  • decreased maximal cardiac output at altitude
44
Q

moderate altitude and VO2 max

A

decreased VO2 max due to decreased arterial PO2

45
Q
A

Exercise Physiology (5 decks)

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