Thermoregulation Flashcards

1
Q

Metabolic rate for heat loss or gain

A

Gain heat

  1. Increase temperature increase metabolic rate
  2. Cold and start shivering to contract muscles and gain heat
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2
Q

Radiation for heat loss or gain

A

Both

  1. Radiating sun = heat gain
  2. Body radiates heat = heat loss
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3
Q

Conduction for heat loss or gain

A

Both
1. sit on cold bench = heat loss
2. Touch hot light bulb = gain heat
Conduction in water is greater than air because air is insulated

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4
Q

Convection for heat loss or gain

A

Heat loss and gain

As long as environment temp is below core temp, will lose heat due to convection opposite occurs when its hot

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5
Q

Evaporation for heat loss or gain

A

Heat loss through sweating and then having it evaporate

Facilitated by convection

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6
Q

What is the benefit of having mechanisms for heat gain and loss?

A

keep the bodies core temp in balance for homeostasis

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7
Q

What does heat exchange rely on?

A

Gradient between skin an the environment

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8
Q

What is the core temp?

A

37 degrees Celsius

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9
Q

What is the skin temp?

A

34 degrees Celsius

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10
Q

What is the primary mechanism for heat loss?

A

Evaporation

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11
Q

What occurs when can’t lose heat by evaporation?

A
  1. Higher core temp

2. Higher sweat rate

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12
Q

What is the bodies response when it is cold?

A
  1. Cutaneous vasoconstriction
  2. Pilorection
  3. Shivering
  4. Non-shivering thermogenesis (increase thyroxin release from thyroid)
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13
Q

What is the bodies response when it is hot?

A
  1. Cutaneous vasodilation

2. sweating and evaporation

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14
Q

Where is the thermoregulatory center?

A

hypothalamus

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15
Q

How is body temperature sensed?

A
  1. Central thermoreceptors
  2. Peripheral thermoreceptors
  3. Hypothalamus set-point
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16
Q

Central thermoreceptors

A

Located in pre-optic anterior hypothalamus (POAH)
More sensitive to heat and elicit VD reflex
Have an Ach cholinergic response

17
Q

Peripheral Thermoreceptors

A

Distributed throughout the skin
More sensitive to cold and elicit VC reflex
Have an alpha adrenergic response

18
Q

Neural control of cutaneous circulation with reflex mechanisms

A

It’s a dual sympathetic innervation
1. Sympathetic adrenergic receptors = vasoconstriction
2. Sympathetic cholinergic receptors = vasodilation
Also have local mechanisms

19
Q

What catecholamine binds to adrenergic receptors?

A

Norepinephrine

20
Q

What catecholamine binds to cholinergic receptors?

A

Ach

21
Q

What is different about acral skin vs. non-acral skin?

A

Acral skin is not dually innervated just have sympathetic adrenergic innervation that causes vasodilation

22
Q

What are the responses in non-acral skin when increase temperature in one area of the body?

A
  1. Passive vasodilation - remove sympathetic tone
  2. Active vasodilation - sympathetic cholinergic response is added
  3. Start sweating when cholinergic response is added
23
Q

What happens to stroke volume in the heat?

A

decreases b/c lose plasma volume

24
Q

What is the compensatory response when stroke volume decreases?

A

increase heart rate

25
Q

Where is most of the blood when the body is in high temperature?

A

Periphery

26
Q

Why does total periphery resistance decrease in the heat?

A

The vessels are vasodilating

27
Q

What does dehydration do to the body?

A

Decrease CO steadily creating competition for blood flow.

  1. Active muscle keeps it the longest
  2. skin lose blood flow second and core temp starts to rise
  3. Inactive tissue (guts) first to lose blood flow for compensatory reasons
28
Q

What beats the greedy bastards with dehydration?

A

Brain

29
Q

What does angiotensin II cause during exercise?

A

Vasoconstriction which increases Blood Pressure

Stimulates thirst centers in hypothalamus

30
Q

What does aldosterone cause during exercise?

A

sodium reabsorption at the kidneys

31
Q

How much fluid should an athlete drink to maintain fluid homestasis?

A

Drink enough to match weight loss

32
Q

How does dehydration impose a thermal and cardiovascular threat?

A

Become hypohydrated which leads to decrease sweating, decrease evaporation, decrease heat loss, increase core temp

33
Q

Heat cramps

A

Na and K losses

34
Q

Heat Exhaustion

A

Volume loss is more detrimental than high core temp

Treat with cooling, fluid, and electrolyte replacement

35
Q

Heat Stroke

A

Brought on by heat exhaustion
Regulatory mechanisms are gone
Treat with rapid cooling

36
Q

Heat injury prevention

A
  1. Recognize symptoms- headaches, chills, confusion
  2. Water availability
  3. Acclimatization
37
Q

What is the significance of acclimation?

A

As the body is acclimatized decrease cardiac output and thermal strain while increasing sweat which increases evaporation and keeps body cool
Need to allow the body to increase plasma volume first couple of times in the environment