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Exercise Physiology > Ch.14 > Flashcards

Ch.14 Flashcards

1
Q

What is thermoregulation?

A

Regulation of body temperature around a physiological set point

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2
Q

What is normal human body temperature?

A

97-100 F or 36.1-37.8 C

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3
Q

How much ATP breakdown produces cellular work (W)?

A

Less than 25%

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4
Q

How much ATP breakdown produces metabolic heat?

A

Greater than 75%

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5
Q

How does heat move from the core to the outside of the body?

A

Blood

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6
Q

How can heat be dissipated when it reaches the skin? (4 ways)

A

Conduction, convection, radiation and evaporation

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7
Q

What is conduction (K)?

A

Heat transfer from one solid material to another through direct molecular contact (negligible)

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8
Q

What is convection (C)?

A

Heat transfer by movement of gas or liquid across a surface

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9
Q

What is radiation (R)?

A

Heat transfer in the form of infrared rays?

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10
Q

What does C + K + R = ?

A

Avenues of dry heat exchange

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11
Q

What is insulation?

A

Resistance to dry heat exchange

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12
Q

What is the ideal insulator?

A

A layer of still air

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13
Q

What is evaporation?

A

Heat loss via phase change from liquid to gas

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14
Q

What is the primary means of heat loss during exercise (~80%)?

A

Evaporation

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15
Q

How does an increase in humidity affect evaporation?

A

Decreases it

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16
Q

How does an decrease in humidity affect evaporation?

A

Increases it

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17
Q

What does prolonged evaporation (sweat) lead to?

A

Dehydration

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18
Q
A
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19
Q

What is responsible for regulating the internal core temperature?

A

Hypothalamus

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20
Q

What does the Preoptic-anterior hypothalamus (POAH) do?

A

Acts as a thermostat for the body and activates thermoregulatory mechanism when temperature deviates

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21
Q

Where are thermoreceptors located?

A

Peripheral in the skin and central in the brain/spinal cord

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22
Q

How does exercise affect metabolic heat load?

A

Increases it

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23
Q

What are the effects of exercise in the heat on cardiovascular function?

A

Skin arterioles VD to increase C heat loss, POAH triggers SNS, Blood volume decreases and SV can’t increase so HR increases to compensate

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24
Q

What happens when the cardiovascular system is overloaded?

A

The heart cannot provide sufficient blood flow to both exercising muscle and the skin (impaired performance)

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25
Q

What is critical temperature theory?

A

The brain shuts down exercise at ~40-41 C

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26
Q

What causes sweating?

A

Hot environmental temperature is higher than skin and core temperatures

27
Q

What is the only avenue of heat loss when heat is higher outside the body?

A

Evaporation

28
Q

What does the POAH control?

A

Eccrine sweat glands

29
Q

What is the electrolyte content like with light sweating?

A

Very dilute

30
Q

What is the electrolyte content like with heavy sweating?

A

Less dilute

31
Q

What hormone does the sweat gland become more sensitive to with training?

A

Aldosterone

32
Q

How much sweat can the body lose during exercise?

A

1.6-2.0 L (2.5%-3.2% body weight) each hour

33
Q

What does exercise and body water loss stimulate?

A

Adrenal cortex and pituitary gland

34
Q

What triggers the release of aldosterone and ADH?

A

Electrolytes

35
Q

What does aldosterone do in the kidneys?

A

Retains Na+

36
Q

What does ADH (vasopressin) do at the kidneys?

A

Retains water

37
Q

What are the 6 risk factors for exercise in the heat?

A

Metabolic heat production, air temp, ambient water vapor (humidity), air velocity, radiant heat sources, and clothing

38
Q

What does the heat index reflect?

A

How it feels outside rather than physiological stress

39
Q

What are the three heat illnesses?

A

Heat cramps, heat exhaustion, heatstroke

40
Q

What are heat cramps triggered by?

A

Na+ losses, dehydration

41
Q

What is heat exhaustion triggered by?

A

Severe dehydration from sweating

42
Q

What happens to thermoregulatory functions during heat exhaustion?

A

They are functional but overwhelmed

43
Q

What triggers heat stroke?

A

Thermoregulatory mechanism failure (core temp > 40 C)

44
Q

What is acclimation?

A

Short-term adaptation to environmental stressor (days/weeks)

45
Q

What is acclimatization?

A

Long-term adaptation to environmental stressor (months/years)

46
Q

True or False
Core temperature lowers during exercise with acclimation

A

True

47
Q

Why does plasma volume increase with acclimation to exercise in the heat?

A

An increase in oncotic pressure (temporary)

48
Q

Does acclimation decrease the HR and increase cardiac output?

A

Yes

49
Q

How does acclimation affect sweating?

A

Causes widespread sweating earlier that is more dilute

50
Q

True or False
Women have the same capacity for exercising in the heat as men at the same relative exercise intensity

A

True

51
Q

Do women or men have lower sweat rates?

A

Women

52
Q

What is cold stress?

A

Any environmental condition causing loss of body heat that threatens homeostasis

53
Q

What does a decrease in core or skin temp trigger?

A

POAH triggers peripheral VC, POAH triggers non-shivering thermogenesis, POAH triggers skeletal muscle shivering, cerebral cortex triggers behavioral adaptations

54
Q

Does windchill affect heat loss?

A

Yes because it is based on air movement not temperature

55
Q

True or False
Water has thermal conductivity 26 times greater than air

A

True

56
Q

How is heat loss affected with moving water?

A

It increases

57
Q

How does muscle function react when exercising in the cold?

A

It decreases in function

58
Q

What is affected by an altered fiber recruitment in the muscle?

A

A lowered contractile force

59
Q

Which muscles are affected by exercising in the cold?

A

Superficial muscles

60
Q

When exercising in the cold, how does fatigue affect metabolic heat production?

A

As fatigue increases, metabolic heat production decreases

61
Q

How is glucose metabolism affected by exercising in the cold?

A

Muscle glycogen utilization is increased and blood glucose is maintained well

62
Q

What is hypothermia?

A

Core temp 34.5-29.5 C which compromised thermoregulatory function

63
Q

What happens when the core temp is <29.5 C?

A

Thermoregulation is completely lost, metabolism slows, drowsiness, lethargy and coma

64
Q

How does low core temp affect HR?

A

SA node is effected which slows the HR

Exercise Physiology (2 decks)

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