Week 8 - Thermoregulation and Heat Stress Flashcards

1
Q

Whats the normal body resting tempreature

A

36.5-37.5 celsius

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2
Q

Whats core body temperature defined as

A

Temperature of the hypothalamus, the thermoregulatory centre of the body

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3
Q

How is heat loss physiologically controlled

A
  1. Body temperature increase is detected
  2. Blood vessels dilate, sweat glands secrete fluid and heat is lost.
  3. This results in heat being lost to the environement
  4. Then body returns back to normal temperature
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4
Q

How is heat retention physiologically controlled

A
  1. Body temperature falls.
  2. Blood vessles constrict, sweat glands do not secrete fluid and heat is conserved. Shivering generates heat so heat is generated
  3. Heat is then retained as a result
  4. Body temperature returns to normal level
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5
Q

How is the heat balance/body temperature maintained

A

Maintained by balancing heat gain and heat loss

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6
Q

What are some examples of heat conservation/production

A

Shivering thermogenesis
Voluntary muscular activity
Non-shivering thermogensis

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7
Q

What are some examples of heat loss

A

Blood reaching the skin
Sweating

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8
Q

Whats a key difference between skin and core temperature

A

Unlike core temperature, skin temperature is not regulated and varies across the body in response to the thermal environment

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9
Q

Whats the effect of hot humid environments on aerobic performance

A

Its impaired

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10
Q

Why is aerobic performance effected in hot conditions

A

There is an increase demand on heat loss mechanisms such as skin blood flow and sweating. There is a reduced gradient between core and skin so therefore core temperature increases

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11
Q

How does dehydration impact heat stress

A

Decreases sweat rate and plasma volume.
Also a further decrease in cardiac output, maximal oxygen uptake, muscle strength and work capacity

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12
Q

Why is pro-longed high intensity training in hot conditions significantly impaired

A

This is because there are competing regulatory demands for blood flow between thermoregulation, working muscle and CNS
Also heat-related changes in skeletal muscle function and metabolism

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13
Q

Whats the most rapid way to lower body temperature

A

Cold water immersion is the most rapid way to lower body temperature

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14
Q

How can you mitigate the impact of heat stress before, immediately before and during exercise
(ON SHEET)

A

Before - heat acclimation and aerobic training
Immediately before - pre-cooling, hydration status
During - Hydration, clothing and cooling

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15
Q

How effect of the acclimatisation response of improved cutaneous blood flow

A

Transports metabolic heat from deep tissue to shell

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15
Q

How effect of the acclimatisation response of effective distribution of cardiac output

A

Appropritate circulation to skin and muscle to meet demands; greater blood pressure stability during exercise

16
Q

How effect of the acclimatisation response of lowered threshold for start of sweating

A

Evaporative cooling begins early in exercise

17
Q

How effect of the acclimatisation response of more effective distribution of sweat over skin surface

A

Optimum use of effective body surface for evaporative cooling

18
Q

How effect of the acclimatisation response of increased sweat output

A

Maximises evaporative cooling

19
Q

How effect of the acclimatisation response of lowered salt concentration of sweat

A

Dilute sweat preserves electrolytes in extraceullular fluid

20
Q

How effect of the acclimatisation response of lower skin and core temperatures and heart rate for standard exercise

A

Frees greater proportion of cardiac output to the active muscles

21
Q

How effect of the acclimatisation response of less reliance on carbohydrate catabolism during exercise

A

Carbohydrate sparing

22
Q

What is hypothermia

A

When heat loss exceeds heat production (conduction, convection, radiation and evaporation) and core temperature drops below 35 celsius.

23
Q

Whats the effects of drops in temperature measuremtns - 2 4 and 6 degrees

A

2 degrees - maximal shivering
4 degrees - ataxia and apathy
6 degrees - unconsciousness
Further drop associated with ventricular fibrillation, reduced brain blood flow, asystole and death

24
Q

Whats the effect of cold on exercise performance

A

Due to shivering oxygen consumption is higher in cold water during sub-maximal exercise but reduced during maximal exercise

25
Q

What is the physiological effect to the increased submaximal vo2 in cold exercise

A

Greater heat loss

26
Q

What is the physiological effect to the decreased exercise capacity in water in cold exercise

A

Greater heat loss

27
Q

What is the physiological effect to the Increased ventilation during submaximal exercise in the cold exercise

A

Increased sympathetic stimulation

28
Q

What is the physiological effect to the Reduced skin blood flow in cold exercise

A

Peripheral vasoconstriction

29
Q

What is the physiological effect to the lower lipid mobilisation in cold exercise

A

reduced blood flow to adipocytes

30
Q

What is the physiological effect to the increased lactate concentration in cold exercise

A

Increased carbohydrate metabolism

31
Q

What is the physiological effect to the Increased central blood volume in cold exercise

A

Peripheral vasoconstriction

32
Q

What is the physiological effect to the decreased heart rate during submaximal exercise in cold exercise

A

Increased central blood volume

33
Q

What is the physiological effect to the release of leptin from adipose tissue in cold exercise

A

Increased sympathetic stimulation

34
Q

What happens as a result of cold acclimatisation/acclimation

A

Results in lower skin temperature at which shivering begins - increased non-shivering thermogenesis.
Maintains higher hand and foot temperature - improved peripheral blood flow
Improved ability to sleep in the cold - due to reduced shivering
Adaptations begin in one week