6.2 Temperature Regulation Flashcards
(109 cards)
0
Q
To maintain body temperature within certain limits
A
Homeostasis
1
Q
Process controlling the balance between heat production and heat loss
A
Thermoregulation
2
Q
Normal body temperature is also known as
A
Normothermia or Euthermia
Note: optimal condition for cellular activity
3
Q
Commonly accepted average core temperature
A
37.0 C or 98.6 F
4
Q
5 major mechanisms of heat production
A
- Basal metabolic rate (BMR)
- Muscle activity
- Metabolic effect of hormones (Thyroxine, GH, Testosterone, NE, E)
- Increased sympathetic activity
- Thermogenic effect of food
5
Q
T/F The most metabolically active produce the least heat
A
False- produce the MOST HEAT
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
7
Q
Increased metabolism of _________ produces ________ times more heat than the rest of the body
A
Skeletal muscle; 30-40
8
Q
Involuntary muscle contraction that is usually a response to cold
A
Shivering
9
Q
Hormones involved in heat gain
A
Thyroxine (response to cold exposure) GH Testosterone Epinephrine Norepinephrine
10
Q
___(1)___ releases TRH -> stimulates pituitary gland to release ____(2)____ -> stimulates thyroid to increase ____(3)____ output
A
- Hypothalamus
- Thyrotropin
- Thyroxine
11
Q
Increased cellular metabolism leads to
A
Heat
12
Q
Causes a decrease in the radiation of heat from skin
A
Skin vasoconstriction
13
Q
Increased metabolic rate leads to the following adrenergic effect
A
Increased HR
Increased respiration
Increased blood glucose levels
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
15
Q
Provides heat to infants to prevent death from hypothermia
A
Brown adipose tissue (BAT)
16
Q
Characteristics of brown fat (4)
A
- Dark color
- Enriched blood supply
- Dense cellular content
- Abundant sympathetic nerve endings
17
Q
__(1)__ from BAT sympathetic nerves is released -> __(2)__ are metabolized -> heat
A
- Norepinephrine
2. Triglycerides
18
Q
T/F When you eat food, the body expends energy
A
True
19
Q
T/F Eating food raises basal metabolic rate
A
True
Note: digestion of food, processing, and absorption of nutrients raises BMR
20
Q
Greatest increase in rate at which the body burns calories happens when what type of diet is taken
A
High protein
21
Q
Flow of transfer of body heat
A
Deep organs and tissues -> skin -> air and surroundings
22
Q
4 major mechanisms of heat loss
A
- Radiation
- Convection
- Conduction
- Evaporation
23
Q
Loss of heat via infrared waves
A
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
