6.2 Temperature Regulation Flashcards Preview

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Flashcards in 6.2 Temperature Regulation Deck (109):
0

Process controlling the balance between heat production and heat loss

Thermoregulation

1

To maintain body temperature within certain limits

Homeostasis

2

Normal body temperature is also known as

Normothermia or Euthermia

Note: optimal condition for cellular activity

3

Commonly accepted average core temperature

37.0 C or 98.6 F

4

5 major mechanisms of heat production

1. Basal metabolic rate (BMR)
2. Muscle activity
3. Metabolic effect of hormones (Thyroxine, GH, Testosterone, NE, E)
4. Increased sympathetic activity
5. Thermogenic effect of food

5

T/F The most metabolically active produce the least heat

False- produce the MOST HEAT

6

When do visceral organs produce the most heat

At rest

Note: approximately 70% of heat is produced by visceral organs during rest

7

Increased metabolism of _________ produces ________ times more heat than the rest of the body

Skeletal muscle; 30-40

8

Involuntary muscle contraction that is usually a response to cold

Shivering

9

Hormones involved in heat gain

Thyroxine (response to cold exposure)
GH
Testosterone
Epinephrine
Norepinephrine

10

___(1)___ releases TRH -> stimulates pituitary gland to release ____(2)____ -> stimulates thyroid to increase ____(3)____ output

1. Hypothalamus
2. Thyrotropin
3. Thyroxine

11

Increased cellular metabolism leads to

Heat

12

Causes a decrease in the radiation of heat from skin

Skin vasoconstriction

13

Increased metabolic rate leads to the following adrenergic effect

Increased HR
Increased respiration
Increased blood glucose levels

14

Mechanism of piloerection

Contraction of arrector pili muscle
-> brings hair upright -> traps a layer of warm air on the skin -> extra insulation

15

Provides heat to infants to prevent death from hypothermia

Brown adipose tissue (BAT)

16

Characteristics of brown fat (4)

1. Dark color
2. Enriched blood supply
3. Dense cellular content
4. Abundant sympathetic nerve endings

17

__(1)__ from BAT sympathetic nerves is released -> __(2)__ are metabolized -> heat

1. Norepinephrine
2. Triglycerides

18

T/F When you eat food, the body expends energy

True

19

T/F Eating food raises basal metabolic rate

True

Note: digestion of food, processing, and absorption of nutrients raises BMR

20

Greatest increase in rate at which the body burns calories happens when what type of diet is taken

High protein

21

Flow of transfer of body heat

Deep organs and tissues -> skin -> air and surroundings

22

4 major mechanisms of heat loss

1. Radiation
2. Convection
3. Conduction
4. Evaporation

23

Loss of heat via infrared waves

Radiation

24

Approximately how much of body heat is lost by radiation

60%

25

Direction of energy flow

Warmer to cooler

26

Conduction is heat transfer between objects in ________

Direct contact

27

Examples of highly conductive surfaces for heat conduction

Metal and rock

28

T/F Low conductive surfaces conduct heat away from the body

False- Highly conductive surfaces

29

Body loses heat about 25 times faster in __(1)___ than in ___(2)___

1. Water
2. Air

30

Transfer of heat by movement of the hot particles to cooler areas

Convection

31

__(1)__ tends to rise and expand while __(2)__ falls

1. Warm air
2. Cool air

32

Substantially enhances heat exchange from the body surface to the air

Convection

33

T/F Convection is enhanced by anything that moves air more rapidly across body surface

True

Note: reason behind the use of fan to cool off

34

Insulating warm air layer that forms around the skin

Epiclimate

Note: forms under windless conditions

35

Mechanism behind wind chill

Wind disrupts epiclimate -> increase rate at which body loses heat

36

T/F Abrupt transition from body temperature to air temperature means a steep thermal gradient

True

37

Evaporation is the loss of heat by

Evaporation of water

38

Approximate amount of water evaporating from lungs and skin

800mL/day or 480kcal/day

39

T/F insensible water loss accompanied by insensible heat loss is significant

False- NOT significant

40

Evaporation becomes sensible heat loss when

Body temperature rises

41

Intense exercise raises the body temperature by

2C to 3C

42

__(1)__ L/hour of perspiration evaporated results to __(2)__ kcal heat removed per hour

1. 1-2 L/hour
2. 2000 kcal

43

Outer parts of the body (skin and subcutaneous tissue) that change temperature depending in the surroundings

Shell or superficial

44

Consist of the thermo-regulated deep tissues of the body and the proximal extremities

Core or internal

Note: normally remains almost constant

45

2 important elements of a thermometer

1. Temperature Sensor
2. Scale

46

4 sites for temperature measurement

1. Anus (rectal temp)
2. Mouth (oral temp)
3. Underarm (axillary temp)
4. Ear (tympanic temp)

47

Sites to get core temperature

1. Oral/mouth
2. Rectal/anus
3. Gut

48

What type of temp is measured in axillary and other skin-based temperatures

Shell temperature

49

0-2 years old : ____(1)____
_____(2)_____ : 36.1C - 37.8C
_____(3)_____ : 35.9C - 37.6C
> 65 years old : ____(4)____

1. 36.4C - 38.0C
2. 3-10 y.o.
3. 11-65 y.o.
4. 35.8C - 37.5C

50

Oral temperature is influenced by

1. Drinking
2. Chewing
3. Smoking
4. Breathing with mouth open

51

T/F Axillary temperature is the longest and most accurate method

False- most INACCURATE method

52

Generally considered the most accurate route of body temperature measurement

Rectal temperature

53

T/F Tympanic temperature correlates closely with core temperature

True

Note: tympanic membrane receives BS from carotid artery which is in close proximity to hypothalamus

54

Thermostat center of the body

Hypothalamus

55

Role of hypothalamus in heat regulation

1. Sensory center
2. Integration center

56

Central thermoreceptors are mainly in ________

Preoptic area of hypothalamus

57

Skin thermoreceptors that mediate neutral, cool, and cold sensations (5C - 45C)

Cold receptors

58

Skin thermoreceptors activated when temp is from 30C - 50C

Warm receptors

59

T/F there are 10 times more cold receptors than heat receptors

True

60

______ establishes a "set-point" for the internal body temperature

Hypothalamus

61

If the two temperatures do not match -> hypothalamus activates heat generation or heat loss mechanism -> adjust ___(1)____ until ___(2)___ is achieved

1. Core temperature
2. Set-point

62

Two nuclei of the hypothalamus that are involved in heat regulation

1. Preoptic area (POA)
2. Anterior hypothalamus (AH)

Note: treated as one area = POA/AH

63

T/F POA/AH monitors its own CNS temperature and receives input from skin receptors

True

64

Compares the detected core temperature to the set-point temperature

POA/AH

65

Damage to POA/AH results to

Hyperthermia

66

________ hypothalamus helps integrate sensory inputs from BOTH central and peripheral thermoreceptors

Posterior

67

Anterior hypothalamus: ______
Posterior hypothalamus: heating up

Cooling down

68

POA/AH : __(1)__
___(2)___: hypothermia

1. Hyperthermia
2. Posterior hypothalamus

69

3 important mechanism to reduce body heat

1. Vasodilation of skin blood vessels
2. Sweating
3. Decreased heat production

70

_____ environment increases core temperature

Hot

71

T/F Passive vasodilation decreases blood flow through anastomoses (AVA)

False- INCREASES

72

Decreases in core temperature via evaporative cooling at skin surface

Sweating

73

Sweating is controlled from a center in the _____ of the hypothalamus

POA/AH

74

Sweat glands are innervated via

Cholinergic sympathetic fibers

75

Sweat is formed in _____ portion of sweat glands

Coiled secretary

Note: electrolyte content similar to plasma

76

Filtrates from sweat passes through the _______

Uncoiled duct

Note: Na and Cl are reabsorbed

77

Final sweat extruded thru the skin pores are _________ to plasma

Hypotonic

78

When the body is exposed to prolonged heat, electrolyte levels may fall and cause ___________

Systemic dehydration

79

Increase in ________ diminishes loss of salt

Aldosterone

80

Process of adjusting to gradual change in environment

Acclimatization

81

T/F An unacclimatized person sweats profusely resulting to large amounts of sodium lost

True

82

After acclimatization, sweating begins earlier at a ______ core temperature

Lower

83

T/F an unacclimatized person sweat profusely but secrete sweat with low sodium concentration

False- acclimatized

84

Corrective mechanisms on a cold day

1. Vasoconstriction of arterioles near skin's surface
2. Decrease production of sweat
3. Increase metabolic rate
4. Shivering

85

T/F Cognitive control of body temp involves conscious voluntary acts to adjust physical characteristics of the air-skin interface

False- Behavioral control
(Ex. Fanning oneself on a hot day)

86

Stretching out body : ___(1)___
_______(2)_______ : heat gain

1. Heat loss/cooling
2. Curling up body

87

Body loses its ability to cool itself

Heat stroke

Note: symptoms
High temp
No sweating
Hot, dry, red skin
Rapid pulse
Confusion, irritability, disorientation, hallucination
Seizures
Loss of consciousness/coma
Death

88

In heat stroke, the internal body temp rises to as high as ______

40.5C or 105F

89

Milder form of heat illness

Heat exhaustion

Note: caused by prolonged exposure to high temp and dehydration

90

T/F there is a normal thermoregulatory system in a person experiencing heat stroke

False- heat exhaustion

91

Management of heat exhaustion

Salt and water replacement
Rest

92

2 types of heat exhaustion

1. Water depletion (excessive thirst, weakness, headache, and loss of consciousness)
2. Salt depletion (nausea and vomiting, muscle cramps and dizziness

93

Heat exhaustion : ___(1)___ pupils
Heat stroke : ___(2)___ pupils

1. Dilated
2. Constricted

94

Painful, brief muscle cramps during exercise in a hot environment

Heat cramps

Note: involves the muscles for heavy work

95

T/F heat cramps is probably due to electrolyte loss

True

96

Core temp drops below 35.0C or 95.0F

Hypothermia

Note: may also be caused by injury to posterior hypothalamus

97

T/F in treating hypothermia restore warmth rapidly

False- Slowly

Note: do not immerse in warm water for rapid warming can cause heart arrhythmia

98

T/F In treating hypothermia, warm the person's trunk first before hands and feet

True

Note: warming extremities first can cause shock

99

State of elevated core temp, which is often, but not necessarily, part of the defensive response of multicellular organisms to the invasion of pathogens

Fever/pyrexia

100

Fever in adults
Oral temp : ___(1)____
Rectal temp : ___(2)____

1. Above 37.8C
2. Above 38.3C

101

T/F A child with fever has a rectal temp of 38.0C and higher

True

102

T/F injury or compression by tumor to the posterior hypothalamus can cause fever

False- preoptic area of hypothalamus

103

Substance that induces fever

Pyrogen

Note: may either be internal (endogenous) or external (exogenous)

104

_____ in the cell wall of some gram positive bacteria are exogenous pyrogen

Lipopolysaccharide (LPS)

105

Sudden resetting of the hypothalamic thermostat to higher level results to a lag between blood temp and the new hypothalamic set-point. This causes

Shivering chills

106

T/F when body temp catches up with new higher set-point, the person no longer experiences chills

True

107

Benefits of fever

1. Increased antibody production
2. Inhibition of pathogen growth

108

Mechanism of aspirin

Inhibits COX -> inhibits Prostaglandin E2 production -> decrease set-point temp -> activate mechanisms of heat loss