Body Temperature Flashcards

1
Q

homeothermic

A

maintaining a relatively constant body temperature, independent of the temperature of the surrounding environment

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2
Q

metabolism

A

makes use of mitochondria to produce energy

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3
Q

core temperature

A

warm, internal

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4
Q

shell temperature

A

cool, external

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5
Q

thermoregulation

A

ability to maintain a constant body temperature despite external temperature changes

temperature regulating centers located in the hypothalamus

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6
Q

mechanisms of heat exchange

A

used to maintain homeostasis when the body isn’t thermoneutral

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7
Q

radiation

A

transfer of heat without contact, from an object to its environment and visa versa via infrared rays

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8
Q

evaporation

A

transfer of heat due to evaporation of water

only way to regulate body temperature when external environment is >37*C

major heat loss mechanism

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9
Q

conduction

A

exchange of heat between objects of different temperatures that are in direct contact

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10
Q

convection

A

transfer of heat through circulation of air currents or liquid along the skin surface

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11
Q

heat loss

A

depends on the blood flow through the skin capillaries

promoted by vasodilation

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12
Q

metabolism

A

major source of internal heat generation

non-hypothalamic

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13
Q

shivering thermogenesis

A

skeletal muscle metabolism

somatic neurons activated

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14
Q

non-shivering thermogenesis

A

brown fat metabolism

SNS activated to release norepinephrine which activates the uncoupling protein for the mitochondrial and oxidative phosphorylation uncoupling

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15
Q

brown fat

A

used in response to cold as it has many mitochondria that can be used for energy (heat) production

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16
Q

heat conservation

A

vasoconstriction
piloerection
behavioral changes

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17
Q

anterior hypothalamus

A

heat loss center

warm-sensing neurons

excited by increase in temperature

stimulates sweating and vasodilation

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18
Q

posterior hypothalamus

A

heat gain center

cold-sensing neurons

excited by decrease in temperature

stimulates conservation, and shivering and non-shivering thermogenesis

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19
Q

thermoreceptors

A

sensory neurons monitor skin and core temperature then send information to the hypothalamus

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20
Q

peripheral thermoreceptors

A

found in the skin

21
Q

central thermoreceptors

A

found in the hypothalamus, viscera, and veins

22
Q

sympathetic nervous system

A

acts on smooth vascular muscle via vasomotor neurons to control vasodilation and vasoconstriction

23
Q

AV shunts

A

short vessels that connect small arteries and small veins

24
Q

cholinergic neurons

A

bind to acetylcholine which induces vasodilation and causes sweating

25
Q

adrenergic neurons

A

bind to epinephrine and norepinephrine which induces vasoconstriction and causes heat conservation

activates cAMP

26
Q

eccrine sweat glands

A

occur over most of the body

open directly onto the surface of the skin

27
Q

apocrine sweat glands

A

open into hair follicles leading to the skin surface

28
Q

hyperthermia

A

body’s temperature rises abnormally high without a change in set point

failure of heat regulating mechanisms - not able to lose heat

29
Q

heat exhaustion

A

high core temperature (37.8-39*C)

severe dehydration due to sweating caused by vigorous exercise in hot humid climates

30
Q

heat stroke

A

extremely high core temperature (>41*C)

fatal hyperthermia caused by heat exposure through environmental factors and physical exercise

31
Q

heat cytotoxicity

A

cytokines released by heat-stressed cells cause local and systemic inflammation and multiple organ failure during heat stroke

32
Q

malignant hyperthermia

A

autosomal dominant genetic disorder

abnormally elevated temperature (44.5*C max)

uncontrolled skeletal muscle contractions triggered by anesthetic agents

33
Q

rhabdomyolysis

A

breakdown of muscle tissue releasing toxic protein (myoglobin) into the blood that results in kidney damage and brown urine which is a symptom of malignant hyperthermia

34
Q

hypothermia

A

core temperature falls below 35*C

body fails to produce enough heat

hypothalamus cannot thermoregulate

35
Q

mild hypothermia

A

32-35*C

shivering
increased pulse and breathing
dehydration

36
Q

moderate hypothermia

A

28-32*C

decreased shivering
rigid muscles
decreased pulse and breathing

37
Q

severe hypothermia

A

<28*C

coma
no pupillary reflex
slugging of RBCs

38
Q

passive external rewarming

A

remove from cold
remove wet clothes
cover with blankets
supply warm fluids

39
Q

active external rewarming

A

immerse in warm water
heat with air warmers
heating pads or hot water bottles

40
Q

invasive active core rewarming

A

warm fluids pumped into stomach
extracorporeal blood rewarming**
inhalation of warm O2
warm IV fluids

41
Q

frostbite

A

localized hypothermic injuries

42
Q

tissue freezing

A

ice crystals form extracellularly causing cellular dehydration and shrinkage

microvascular blood flow occlusion leads to ischemia and thrombosis resulting in tissue damage

43
Q

artificial hypothermia

A

induced artificially during surgery using sedatives (21-24*C)

44
Q

fever/pyrexia

A

elevation of body temperature above normal (37-39*C) as a result of the hypothalamic thermostat being reset due to an immune response

45
Q

pyrogens

A

fever reducing substances

46
Q

exogenous pyrogens

A

not bodily derived

produced by pathogens

47
Q

endogenous pyrogens

A

bodily derived

released in response to exogenous pyrogens

produced by leukocytes and macrophages

48
Q

metabolic shift during fever

A

glucose is a bacterial growth medium so switch to protein and fat breakdown

prolonged fever results in fat loss due to high levels of ketones that lead to metabolic acidosis

49
Q

antipyretics

A

drugs that lower fever by resetting the set point to lower or normal values

inhibits PGE2 production by inhibiting COX-2