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Physiology > 6.2 Temperature Regulation > Flashcards

6.2 Temperature Regulation Flashcards

0
Q

To maintain body temperature within certain limits

A

Homeostasis

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1
Q

Process controlling the balance between heat production and heat loss

A

Thermoregulation

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2
Q

Normal body temperature is also known as

A

Normothermia or Euthermia

Note: optimal condition for cellular activity

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3
Q

Commonly accepted average core temperature

A

37.0 C or 98.6 F

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4
Q

5 major mechanisms of heat production

A
  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
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5
Q

T/F The most metabolically active produce the least heat

A

False- produce the MOST HEAT

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6
Q

When do visceral organs produce the most heat

A

At rest

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

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7
Q

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

A

Skeletal muscle; 30-40

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8
Q

Involuntary muscle contraction that is usually a response to cold

A

Shivering

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9
Q

Hormones involved in heat gain

A 
Thyroxine (response to cold exposure)
GH
Testosterone
Epinephrine
Norepinephrine
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10
Q

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

A
  1. Hypothalamus
  2. Thyrotropin
  3. Thyroxine
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11
Q

Increased cellular metabolism leads to

A

Heat

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12
Q

Causes a decrease in the radiation of heat from skin

A

Skin vasoconstriction

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13
Q

Increased metabolic rate leads to the following adrenergic effect

A

Increased HR
Increased respiration
Increased blood glucose levels

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14
Q

Mechanism of piloerection

A

Contraction of arrector pili muscle

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

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15
Q

Provides heat to infants to prevent death from hypothermia

A

Brown adipose tissue (BAT)

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16
Q

Characteristics of brown fat (4)

A
  1. Dark color
  2. Enriched blood supply
  3. Dense cellular content
  4. Abundant sympathetic nerve endings
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17
Q

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

A
  1. Norepinephrine

2. Triglycerides

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18
Q

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

A

True

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19
Q

T/F Eating food raises basal metabolic rate

A

True

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

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20
Q

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

A

High protein

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21
Q

Flow of transfer of body heat

A

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

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22
Q

4 major mechanisms of heat loss

A
  1. Radiation
  2. Convection
  3. Conduction
  4. Evaporation
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23
Q

Loss of heat via infrared waves

A

Radiation

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24
Q

Approximately how much of body heat is lost by radiation

A

60%

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25
Q

Direction of energy flow

A

Warmer to cooler

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26
Q

Conduction is heat transfer between objects in ________

A

Direct contact

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27
Q

Examples of highly conductive surfaces for heat conduction

A

Metal and rock

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28
Q

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

A

False- Highly conductive surfaces

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29
Q

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

A
  1. Water

2. Air

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30
Q

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

A

Convection

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31
Q

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

A
  1. Warm air

2. Cool air

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32
Q

Substantially enhances heat exchange from the body surface to the air

A

Convection

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33
Q

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

A

True

Note: reason behind the use of fan to cool off

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34
Q

Insulating warm air layer that forms around the skin

A

Epiclimate

Note: forms under windless conditions

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35
Q

Mechanism behind wind chill

A

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

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36
Q

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

A

True

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37
Q

Evaporation is the loss of heat by

A

Evaporation of water

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38
Q

Approximate amount of water evaporating from lungs and skin

A

800mL/day or 480kcal/day

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39
Q

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

A

False- NOT significant

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40
Q

Evaporation becomes sensible heat loss when

A

Body temperature rises

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41
Q

Intense exercise raises the body temperature by

A

2C to 3C

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42
Q

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

A
  1. 1-2 L/hour

2. 2000 kcal

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43
Q

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

A

Shell or superficial

44
Q

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

A

Core or internal

Note: normally remains almost constant

45
Q

2 important elements of a thermometer

A
  1. Temperature Sensor

2. Scale

46
Q

4 sites for temperature measurement

A
  1. Anus (rectal temp)
  2. Mouth (oral temp)
  3. Underarm (axillary temp)
  4. Ear (tympanic temp)
47
Q

Sites to get core temperature

A
  1. Oral/mouth
  2. Rectal/anus
  3. Gut
48
Q

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

A

Shell temperature

49
Q

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

A
  1. 36.4C - 38.0C
  2. 3-10 y.o.
  3. 11-65 y.o.
  4. 35.8C - 37.5C
50
Q

Oral temperature is influenced by

A
  1. Drinking
  2. Chewing
  3. Smoking
  4. Breathing with mouth open
51
Q

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

A

False- most INACCURATE method

52
Q

Generally considered the most accurate route of body temperature measurement

A

Rectal temperature

53
Q

T/F Tympanic temperature correlates closely with core temperature

A

True

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

54
Q

Thermostat center of the body

A

Hypothalamus

55
Q

Role of hypothalamus in heat regulation

A
  1. Sensory center

2. Integration center

56
Q

Central thermoreceptors are mainly in ________

A

Preoptic area of hypothalamus

57
Q

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

A

Cold receptors

58
Q

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

A

Warm receptors

59
Q

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

A

True

60
Q

______ establishes a “set-point” for the internal body temperature

A

Hypothalamus

61
Q

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

A
  1. Core temperature

2. Set-point

62
Q

Two nuclei of the hypothalamus that are involved in heat regulation

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

Note: treated as one area = POA/AH

63
Q

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

A

True

64
Q

Compares the detected core temperature to the set-point temperature

A

POA/AH

65
Q

Damage to POA/AH results to

A

Hyperthermia

66
Q

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

A

Posterior

67
Q

Anterior hypothalamus: ______

Posterior hypothalamus: heating up

A

Cooling down

68
Q

POA/AH : __(1)__

___(2)___: hypothermia

A
  1. Hyperthermia

2. Posterior hypothalamus

69
Q

3 important mechanism to reduce body heat

A
  1. Vasodilation of skin blood vessels
  2. Sweating
  3. Decreased heat production
70
Q

_____ environment increases core temperature

A

Hot

71
Q

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

A

False- INCREASES

72
Q

Decreases in core temperature via evaporative cooling at skin surface

A

Sweating

73
Q

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

A

POA/AH

74
Q

Sweat glands are innervated via

A

Cholinergic sympathetic fibers

75
Q

Sweat is formed in _____ portion of sweat glands

A

Coiled secretary

Note: electrolyte content similar to plasma

76
Q

Filtrates from sweat passes through the _______

A

Uncoiled duct

Note: Na and Cl are reabsorbed

77
Q

Final sweat extruded thru the skin pores are _________ to plasma

A

Hypotonic

78
Q

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

A

Systemic dehydration

79
Q

Increase in ________ diminishes loss of salt

A

Aldosterone

80
Q

Process of adjusting to gradual change in environment

A

Acclimatization

81
Q

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

A

True

82
Q

After acclimatization, sweating begins earlier at a ______ core temperature

A

Lower

83
Q

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

A

False- acclimatized

84
Q

Corrective mechanisms on a cold day

A
  1. Vasoconstriction of arterioles near skin’s surface
  2. Decrease production of sweat
  3. Increase metabolic rate
  4. Shivering
85
Q

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

A

False- Behavioral control

Ex. Fanning oneself on a hot day

86
Q

Stretching out body : ___(1)___

_______(2)_______ : heat gain

A
  1. Heat loss/cooling

2. Curling up body

87
Q

Body loses its ability to cool itself

A

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
Q

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

A

40.5C or 105F

89
Q

Milder form of heat illness

A

Heat exhaustion

Note: caused by prolonged exposure to high temp and dehydration

90
Q

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

A

False- heat exhaustion

91
Q

Management of heat exhaustion

A

Salt and water replacement

Rest

92
Q

2 types of heat exhaustion

A
  1. Water depletion (excessive thirst, weakness, headache, and loss of consciousness)
  2. Salt depletion (nausea and vomiting, muscle cramps and dizziness
93
Q

Heat exhaustion : ___(1)___ pupils

Heat stroke : ___(2)___ pupils

A
  1. Dilated

2. Constricted

94
Q

Painful, brief muscle cramps during exercise in a hot environment

A

Heat cramps

Note: involves the muscles for heavy work

95
Q

T/F heat cramps is probably due to electrolyte loss

A

True

96
Q

Core temp drops below 35.0C or 95.0F

A

Hypothermia

Note: may also be caused by injury to posterior hypothalamus

97
Q

T/F in treating hypothermia restore warmth rapidly

A

False- Slowly

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

98
Q

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

A

True

Note: warming extremities first can cause shock

99
Q

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

A

Fever/pyrexia

100
Q

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

A
  1. Above 37.8C

2. Above 38.3C

101
Q

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

A

True

102
Q

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

A

False- preoptic area of hypothalamus

103
Q

Substance that induces fever

A

Pyrogen

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

104
Q

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

A

Lipopolysaccharide (LPS)

105
Q

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

A

Shivering chills

106
Q

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

A

True

107
Q

Benefits of fever

A
  1. Increased antibody production

2. Inhibition of pathogen growth

108
Q

Mechanism of aspirin

A

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

Physiology (27 decks)

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