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BIOL241 > Topic 8: Thermoregulation > Flashcards

Topic 8: Thermoregulation Flashcards

(58 cards)

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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

Study These Flashcards
A

Tb fluctuates with Ta (ie. seasonal changes)

25
Endotherm
uses metabolism to generate body heat (internal heat generation)
26
Ectotherm
aquires body heat from environment (external heat source)
27
4 Behavioural Regulation of Conductance:
- in an attempt to optimize heat exchange w/ the environment to attain an ideal body temperature: exposure grouping dormancy migration
28
9 Physiological Regulation of Conductance:
- - 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
Exposure:
moving in/out of sun/wind or increasing/decreasing surface area
30
Grouping
huddling together to share radiation
31
Dormancy
Daily torpor & hibernation or winter sleep
32
Hibernation
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
Migration
complete avoidance of poor environmental conditions
34
Membrane Acclimation
- 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
Blood Flow
vasodilation & vasoconstriction
36
Vasoconstriction occurs when there is __________ conductance with the environment
decreasedV
37
Vasodilation occurs when there is _________________ conductance with the environment
increased
38
Endotherms ________ when cold to retain heat
vasoconstrict
39
Endotherms ___________ when hot to release heat
vasodilate
40
Ectotherms __________ when hot to retain heat
vasoconstrict
41
Ectotherms ___________ when cold to increase heat gained from environment
vasodilate
42
Insulation
fat/blubber, fur/feathers, piloerection
43
Fat/blubber provides _____ insulation to __________________________
internal; slow heat transfer
44
Fur/feathers provide _____ insulation to ____________________-
external; slow heat transfer
45
piloerection is the _________ of feathers/fur __________ the rate of heat transfer by ___________ thickness of insulation layers
fluffing; decreases; increases
46
Fur length & colour
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
Best combination of fur and skin colour for best insulation is:
white fur and black skin
48
Sweating/panting allows ___________ through _____________
heat loss; evapouration
49
Cyroprotectants are __________ produced to ______________
molecules (glucose/glycerol); lower freezing point
50
Ice-nucleating Agents are ______________________ that prevents ______ from forming
antifreeze proteins; ice
51
Shivering thermogenesis is the:
simultaneous action of antagonistic muscles that generates heat without causing movement
52
Non-shivering thermogenesis:
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
Non-shivering thermogenesis raises ____ for ___________
Tb; newborns, those recovering from torpor. hibernation, or winter sleep
54
Thermal neutral zone
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
what happens to homeothermic endotherm when the Tb is below thermal neutral zone?
endotherm increases metabolic rate to generate more body heat and maintain its Tb
56
what happens to homeothermic endotherms when Tb is above thermal neutral zone?
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
Effect of high conductance
increases rate of heat exchange from body to environment to increase heat loss through behavioural and physiological regulation methods
58
Effect of low conductance
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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