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BIOL241 > Topic 8: Thermoregulation > Flashcards

Topic 8: Thermoregulation Flashcards

1
Q

Homeostasis

A

regulation of internal environment in the face of changes in the external environment (dynamic process)

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2
Q

What parameters must organisms control for homeostasis?

A
  • pH
  • temperature
  • O2/Co2
  • heart rate
  • solutes
  • water (volume and pressure of cells & blood plasma)
  • osmoregulation
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3
Q

Negative Feedback Mechanisms

A

a change in a variable under homeostatic control triggers a response that OPPOSES the change

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4
Q

Sensor

A

detects environmental conditions

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5
Q

Integrator

A

analyzes sign from signal; compares conditions to the set point & activates effector

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6
Q

Effector

A

causes a physiological change that opposes the deviation from the set point

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7
Q

Role of sensor in temperature regulation

A

detects temp. in skin

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8
Q

What is the integrator in temperature regulation

A

hypothalamus

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9
Q

What is the effector in temperature regulation?

A

muscle tissue, vasculature, sweat glands

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10
Q

Positive Feedback Mechanisms

A

change in a variable under homeostatic control triggers a response that AMPLIFIES the change

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11
Q

Thermoregulation

A

regulating internal body temperature
- this has huge impact on energy budgets

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12
Q

Ta

A

ambient temperature

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13
Q

Tb

A

body temperature

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14
Q

Body heat

A

generated by metabolism
can be exchanged with environment
regulated by changing rate of heat gain/loss

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15
Q

The rate of heat exchange is called

A

conductance

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16
Q

4 ways heat can be exchanged with the environment is:

A

conduction
convection
evaporation
radiation

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17
Q

What is the adaptation for heat retention?

A

low conductance

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18
Q

What is the adaptation for heat loss?

A

high conductance

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19
Q

How do ectotherms primarily regulate Tb?

A

using behaviour

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20
Q

When temperature rises above thermal neutral zone, homeothermic endotherms risk entering state of _______________

A

hyperthermia

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21
Q

Animals _______ have to spend energy to maintain body temperature during hibernation

A

do

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22
Q

____________ have a broader range of temperatures

A

endotherms

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23
Q

Homeotherms

A

maintain constant Tb independant of Ta

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24
Q

Heterotherms

A

Tb fluctuates with Ta (ie. seasonal changes)

25
Q

Endotherm

A

uses metabolism to generate body heat (internal heat generation)

26
Q

Ectotherm

A

aquires body heat from environment (external heat source)

27
Q

4 Behavioural Regulation of Conductance:

A
  • in an attempt to optimize heat exchange w/ the environment to attain an ideal body temperature:

exposure
grouping
dormancy
migration

28
Q

9 Physiological Regulation of Conductance:

A
    • in an attempt to optimize heat exchange w/ the environment to attain an ideal body temperature:

membrane acclimation
blood flow
insulation
fur length & colour
sweating/panting
cryoprotectants
ice-nucleating agents
shivering thermogenesis
non-shivering thermogenesis

29
Q

Exposure:

A

moving in/out of sun/wind or increasing/decreasing surface area

30
Q

Grouping

A

huddling together to share radiation

31
Q

Dormancy

A

Daily torpor & hibernation or winter sleep

32
Q

Hibernation

A

usually lasts 2 weeks
Tb is regulated close to Ta
massive decrease in MR
non-shivering thermogenesis occurs when organism wakes up for 1-2 days

33
Q

Migration

A

complete avoidance of poor environmental conditions

34
Q

Membrane Acclimation

A
  • organisms adjust cellular conditions to work optimally in cold & warm environments
  • membrane viscosity is affected by temperature
  • different conformation decreases the enzyme’s optimum temperature
  • increase in enzyme concentration counters lower activity
  • phospholipid change level of saturation
  • accumulation of changes in every cell acclimates the entire organism
35
Q

Blood Flow

A

vasodilation & vasoconstriction

36
Q

Vasoconstriction occurs when there is __________ conductance with the environment

A

decreasedV

37
Q

Vasodilation occurs when there is _________________ conductance with the environment

A

increased

38
Q

Endotherms ________ when cold to retain heat

A

vasoconstrict

39
Q

Endotherms ___________ when hot to release heat

A

vasodilate

40
Q

Ectotherms __________ when hot to retain heat

A

vasoconstrict

41
Q

Ectotherms ___________ when cold to increase heat gained from environment

A

vasodilate

42
Q

Insulation

A

fat/blubber, fur/feathers, piloerection

43
Q

Fat/blubber provides _____ insulation to __________________________

A

internal; slow heat transfer

44
Q

Fur/feathers provide _____ insulation to ____________________-

A

external; slow heat transfer

45
Q

piloerection is the _________ of feathers/fur __________ the rate of heat transfer by ___________ thickness of insulation layers

A

fluffing; decreases; increases

46
Q

Fur length & colour

A

thicker fur provides better insulation

white fur: allows light to reach the skin
black fur: absorbs light and generates heat outside of the insulation layer
black skin: absorbs light and generates heat inside insulation layer

47
Q

Best combination of fur and skin colour for best insulation is:

A

white fur and black skin

48
Q

Sweating/panting allows ___________ through _____________

A

heat loss; evapouration

49
Q

Cyroprotectants are __________ produced to ______________

A

molecules (glucose/glycerol); lower freezing point

50
Q

Ice-nucleating Agents are ______________________ that prevents ______ from forming

A

antifreeze proteins; ice

51
Q

Shivering thermogenesis is the:

A

simultaneous action of antagonistic muscles that generates heat without causing movement

52
Q

Non-shivering thermogenesis:

A

special fat tissue (brown fat) is loaded with special mitochondira

  • instead of using the PMF for ATP synthase, it is used to generate heat:
  • electrons released are sent to UCP1 instead of ATP synthase that releases more energy as heat
53
Q

Non-shivering thermogenesis raises ____ for ___________

A

Tb; newborns, those recovering from torpor. hibernation, or winter sleep

54
Q

Thermal neutral zone

A

the range of temperatures where the metabolic rate of an organism is at its minimum, and the organism does not need to expend energy to maintain its body temperature

55
Q

what happens to homeothermic endotherm when the Tb is below thermal neutral zone?

A

endotherm increases metabolic rate to generate more body heat and maintain its Tb

56
Q

what happens to homeothermic endotherms when Tb is above thermal neutral zone?

A

endotherms must dissipate excess heat produced by their metabolism through behavioural and physiological regulation methods of conductance: this may involve vasodilation, panting, or sweating.

57
Q

Effect of high conductance

A

increases rate of heat exchange from body to environment to increase heat loss through behavioural and physiological regulation methods

58
Q

Effect of low conductance

A

decreases rate of heat exchange from body to environment to increase heat retention through behavioural and physiological regulation methods

BIOL241 (6 decks)

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