9 - Fever Flashcards

1
Q

Why must humans maintain a stable body temperature within a narrow range?

A

Metabolic processes are dependent on temperatures being kept within that range

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2
Q

Name the condition where the body temperature is too high.

A

Hyperthermia

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3
Q

Name the condition where the body temperature is too low.

A

Hypothermia

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4
Q

Why is temperature different at surfaces of the body than at its core?

A

Surfaces exchange heat with the environment

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5
Q

How is body temperature kept relatively stable?

A

Circulation of blood

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6
Q

What is the normal range for core temperature?

A

36.2 to 37.4 deg C

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7
Q

Time of day and point in the ___ cycle cause temperature to fluctuate.

A

Menstrual

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8
Q

Why does the temperature on the forehead tend to be lower than the core body temperature?

A

Environmental temperature cools it down

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9
Q

Of the following, list the 2 most accurate areas to measure core body temperature: armpit, mouth, rectum, vagina.

A
  1. Rectum

2. Vagina

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10
Q

Of the following, list the 2 least accurate areas to measure core body temperature: armpit, mouth, rectum, vagina.

A
  1. Mouth

2. Armpit

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11
Q

Order the following areas from most to least accurate for measurement of core body temperature.

  1. Ear
  2. Mouth + Armpit
  3. Rectum + Vagina
A
  1. Rectum + Vagina
  2. Ear
  3. Mouth + Armpit
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12
Q

Symptoms of hyperthermia manifest primarily in the ___ nervous system.

A

Central

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13
Q

Symptoms of hypothermia manifest primarily in the ___ nervous system.

A

Central

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14
Q

The main effect of hypothermia is a slowing down of metabolism. What are some signs and symptoms that would be indicative of a dangerously slow metabolism?

A
  • Low heart rate
  • Weak pulse
  • Slurred speech
  • Sluggishness
  • Clumsiness
  • Memory loss
  • Unconsciousness
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15
Q

The main effect of hyperthermia is a speeding up of metabolism. What are some signs and symptoms that would be indicative of a dangerously fast metabolism?

A
  • Cramps
  • Nausea
  • Vomiting
  • Headache
  • Dizziness
  • Fainting
  • Coma
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16
Q

Compare the effect of hyperthermia and hypothermia on metabolic rate.

A

Hyperthermia: increases metabolic rate
Hypothermia: decreases metabolic rate

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17
Q

Hyperthermia ___ metabolic rate.

A

Increases

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18
Q

Hypothermia ___ metabolic rate.

A

Decreases

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19
Q

Body temperature above ___ deg C can be very dangerous.

A

40

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20
Q

Body temperature below ___ deg C can be fatal.

A

28

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21
Q

What is the typical age for a febrile convulsion?

A

6 months to 5 years

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22
Q

A child has a febrile convulsion. When you see them, they are not fully alert. What are the first two things you should do?

A
  1. Put the child in the recovery position

2. Maintain their vital signs

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23
Q

A child presents with a febrile convulsion. List 4 illnesses that need to be excluded.

A
  1. Meningitis
  2. Septicemia
  3. UTI
  4. Chest infection
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24
Q

What type of parasite causes malaria?

A

Plasmodium

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25
Q

How does malaria induce pallor?

A

Causes the blood vessels to constrict

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26
Q

What stain would identify malaria in a blood film?

A

Giemsa

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27
Q

Abnormal body temperature is dangerous both for its own effects and for the mechanisms by which the body tries to ___ it.

A

Control

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28
Q

Why are you more likely to feel cold sitting next to a window with no curtains?

A

Body loses heat via radiation to a nearby cold surface

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29
Q

Abnormal body temperature mainly affects which system?

A

CNS (central nervous system)

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30
Q

Describe why some surgeries are performed after cooling the body temperature.

A

Lower body temperature ->
Lower metabolic rate ->
Reduced oxygen requirements ->
Body parts less vulnerable to lack of oxygen

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31
Q

The core temperature depends on the balance between heat lost and heat ___.

A

Gained

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32
Q

How does exercise increase body heat?

A

Raises metabolic rate

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33
Q

Why do you feel hotter after eating a meal?

A

Increased metabolic rate raises core body temperature

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34
Q

List 2 involuntary physiological mechanisms for increasing body heat.

A
  1. Shivering

2. Activation of brown adipose tissue

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35
Q

What are the 4 processes by which body heat can be lost?

A
  1. Convection
  2. Conduction
  3. Radiation
  4. Evaporation
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36
Q

Why do convection, conduction, and radiation only reduce body heat when the environment is cooler than the body?

A

Heat must SHIFT from the body to the environment

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37
Q

Which form of heat loss can occur even when the environment is hotter than the body?

A

Evaporation (via sweat)

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38
Q

Air is a ___ conductor.

A

Poor

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39
Q

List 2 ways that clothes keep the body warm. (Hint: both related to air.)

A
  1. Trap air, which is a good insulator

2. Reduce convective loss

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40
Q

In which condition would air, which a good insulator, actually reduce body heat?

A

When it is flowing (e.g., wind chill)

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41
Q

What is conduction (re: body heat)?

A

When body heat shifts to a cooler object via direct physical contact

42
Q

What is radiation (re: body heat)?

A

When body heat shifts to a cooler object via EMR waves

43
Q

What is convection (re: body heat)?

A

When body heat is lost via air movement

44
Q

Which unit measures the insulating properties of clothes?

A

Tog

45
Q

Water is a ___ conductor.

A

Good

46
Q

List 2 situations where the body would lose heat via conduction.

A
  1. Immersed in cold WATER (e.g., Jack from Titanic)

2. Lying on a cold SURFACE (e.g, drunk person lying in a ditch)

47
Q

Why would wearing a scarf and toque prevent convective heat loss?

A

Warm air rises

48
Q

What percentage of body heat do babies lose from the head?

A

80%

49
Q

How would long, flowy clothes keep the body cool?

A

Promote convective heat loss (i.e., warm air rises from the top and is replaced by cool air coming in from the bottom, creating a fan-like effect)

50
Q

What is the major mechanism for loss of body heat in adults?

A

Radiation (accounts for 60-70% of heat loss)

51
Q

List 3 variables that determine the rate at which heat radiates from the outermost surface of the body to surrounding surfaces.

A
  1. Temperature difference
  2. Distance
  3. Color
52
Q

What is latent heat?

A

The heat needed to convert liquid water to vapour

53
Q

The body loses heat when sweat ___.

A

Evaporates

54
Q

How do aluminum space blankets keep the body warm?

A

REFLECT heat back onto the body surface

55
Q

Water evaporates CONSTANTLY from the skin surface and ___ tract.

A

Respiratory

56
Q

Water evaporates CONSTANTLY from the skin surface and respiratory tract. This is known as ___ evaporation.

A

Insensible

57
Q

What is the thermo-neutral temperature?

A

Environmental temperature at which core body temperature does not change

58
Q

List 2 variables that affect the thermo-neutral temperature.

A
  1. Body’s heat production

2. Amount of insulation (i.e., how hard it is to lose heat)

59
Q

Hard exercise will ___ the thermo-neutral temperature.

A

Decrease

60
Q

Heavy clothing will ___ the thermo-neutral temperature.

A

Decrease

61
Q

Our bodies adjust heat loss and gain to make the environment that we’re in ___.

A

Thermo-neutral

62
Q

Compare blood flow to the skin in cold and warm conditions.

A

Cold: reduced
Warm: increased

63
Q

Brown adipose tissue generates heat by uncoupling which cellular process?

A

Oxidative phosphorylation

64
Q

The activation of brown adipose tissue is driven by the ___ nervous system.

A

Sympathetic

65
Q

Compare the amplitude and frequency of muscle contractions during shivering.

A

Amplitude: low
Frequency: high

66
Q

Why are UTIs more common in women than in men?

A

The opening of the female urethra is CLOSER to the anal canal, which is a common source for bacteria causing UTIs

67
Q

What is atrophic vaginitis?

A

Thinning and drying of vaginal tissue due to lack of estrogen

68
Q

Why are UTIs more common in older men than younger men?

A

Aging might lead to PROSTATE ENLARGEMENT, which impedes bladder emptying and causes bacteria to fester

69
Q

Why are UTIs more common in older women than younger women?

A

Menopause causes thinning and drying of tissue around the urethra (i.e., atrophic vaginitis), thus the tissue cannot repel bacteria as well

70
Q

What are the 2 most common tests for UTIs?

A
  1. Dipstick

2. Urine sample

71
Q

What is the most common bacteria causing UTIs?

A

E. coli

72
Q

In sweat glands, acini produce secretions and ducts remove the solute, leaving water. Why does profuse sweat taste saltier?

A

The more you sweat, the less salt is recovered by sweat ducts

73
Q

List 2 complications of excessive sweating.

A
  1. Dehydration

2. Salt deprivation

74
Q

What part of the brain regulates body temperature?

A

Hypothalamus

75
Q

Which type of cells in the hypothalamus detect core body temperature by monitoring blood temperature?

A

Nerve cells

76
Q

What is the set point?

A

A desired value determined by the hypothalamus (picture: thermostat)

77
Q

How does DNP cause hyperthermia?

A

Leads to an uncontrolled increase in metabolism

78
Q

A ___ is a temperature above the normal range, resulting from an increase in the set point.

A

Fever

79
Q

List 2 non-pathological triggers that alter the set point.

A
  1. Circadian rhythm

2. Menstrual cycle

80
Q

Core body temperature ___ at night.

A

Decreases

81
Q

Core body temperature ___ during the luteal phase (2nd half) of the menstrual cycle.

A

Increases

82
Q

What is a pyrogen?

A

A fever-inducing agent

83
Q

Pyrexia is a synonym for ___.

A

Fever

84
Q

What is the term for a substance travelling in the blood stream that elevates the set point for body temperature?

A

Pyrogen

85
Q

Which body system produces endogenous pyrogens?

A

Immune system

86
Q

Cytokines are ___ pyrogens.

A

Endogenous

87
Q

What produces exogenous pyrogens?

A

Pathogens

88
Q

Although pathogens are exogenous pyrogens, they almost always act by stimulating ___ pyrogens.

A

Endogenous

89
Q

All pyrogens lead to the production of ___, which act on the hypothalamus.

A

Prostaglandins

90
Q

Anti-pyrexic drugs (e.g., acetaminophen) ___ prostaglandin production.

A

Inhibit

91
Q

How do anti-pyrexic drugs (e.g., acetaminophen) inhibit prostaglandin production?

A

Act on COX enzymes

92
Q

Which enzymes produce prostaglandins?

A

COX enzymes

93
Q

In broad terms, which physiological process generates most body heat?

A

Metabolism

94
Q
The following describes how a fever is induced. 
Pyrogen enters bloodstream ->
Stimulation of \_\_\_ ->
Increased set point in hypothalamus -> 
Body temperature rises
A
The following describes how a fever is induced. 
Pyrogen enters bloodstream ->
Stimulation of PROSTAGLANDINS ->
Increased set point in hypothalamus -> 
Body temperature rises
95
Q

Which medical condition arises from an adversely high body temperature?

A

Heat stroke

96
Q

Why would a fever cause you to shiver despite a raised body temperature?

A

Raised set point causes your body to act as if you are cold

97
Q

Pyrogens are often produced in waves. Describe how this would induce sweating during a fever.

A

Pyrogen concentration falls ->
Set point reduced ->
Body acts as if temperature is too high ->
Sweating to increase heat loss

98
Q

Why would you suddenly feel hot when a fever breaks?

A

Pyrogen concentration in the blood falls, lowering the set point

99
Q

List 2 effects of exercise on insulin.

A
  1. More rapid absorption

2. Increased effectiveness

100
Q

How does exercise reduce the demand on pancreatic beta cells?

A

Stimulates non-insulin dependent glucose uptake into muscle