T8 Thermoregulation Flashcards

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1
Q

Homeostasis

A

regulation of internal environment in face of changes in external environment

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2
Q

Parameters of homeostasis

A

pH, water (volume and pressure of cells and blood plasma, osmoregulation), solutes, temperature, O2/CO2, heart rate.

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3
Q

Negative feedback mechanisms

A

change in a variable under homeostatic control triggers response that opposes change

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4
Q

Sensor

A

detects environmental conditions

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5
Q

Integrator

A

analyzes signal from sensor, compares conditions to set point and activates appropriate effector

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6
Q

Effector

A

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

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7
Q

Positive feedback mechanisms

A

change in a variable under homeostatic control triggers a response that amplifies change

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8
Q

Thermo regulation .

A

regulating internal body temp

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9
Q

Ambient Temperature

A

Ta

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10
Q

Body temperature

A

Tb

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11
Q

Heat generated by metabolism

A

body heat

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12
Q

Heat can be exchanged with environments by conduction, convection, evaporation and radiation

A

body heat

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13
Q

Have lower conductance due to Smaller SA/V ratios

A

Large organisms

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14
Q

Homeotherm

A

maintains constant body temperature (Tb) independent of ambient temperature

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15
Q

Heterotherm

A

Tb fluctuates

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16
Q

Endotherm

A

uses metabolism to generate body heat (internal heat source)

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17
Q

Ectotherm

A

acquires body heat from environment (external heat sources)

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18
Q

Thermal Neutral Zone

A

temperature range around an animal where it can maintain its normal body temperature without using extra energy.

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19
Q

Below TNZ (hypothermy)

A

Shivering, vasoconstriction, piloerection, decreasing surface area, decreasing exposure (huddling/burrowing)

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20
Q

Above TNZ (Hyperthermy)

A

Panting, vasodilation, sweating, increasing surface area, decreasing exposure (to sun)

21
Q

Long term thermoregulation

A

Growing fur/adding fat, shedding, changing colour

22
Q

Behavioural Regulation of Conductance

A

Moving to optimize heat exchange with the environment to attain an ideal body temperature

23
Q

Exposure

A

movement into, or out of, the sun/wind. Surface area

24
Q

Grouping

A

huddling together to share radiation

25
Q

Dormancy

A

break in organism’s life when it takes a rest, pausing growth and activity to save energy.

26
Q

Daily torpor

A

A short (6-8 hours) reduction in activity ~10C drop in Tb and a lower MR Reduce spending energy to stay warm (especially when food is scarce in winter)

27
Q

Hibernation

A

Tb regulated close to Ta • Massive reduction in MR • Lasts ~2 weeks before arousal • Requires massive heat generation for arousal • Awake for 1-2 days and then repeats

28
Q

Migration

A

Complete avoidance of poor environmental conditions

29
Q

Membrane Acclimation

A

Changes in ambient temperature and osmolarity cause fluctuations in the fluidity of cell membranes.

30
Q

Acclimated to 5C

A

lots of unsaturated fatty acids in membranes. At 25C membranes too fluid

31
Q

Acclimated to 25C

A

lots of saturated fatty acids in membranes. At 5C are too viscous

32
Q

Vasoconstriction

A

Decreases conductance with environment

33
Q

Vasoconstriction Endotherms

A

when cold to retain heat

34
Q

Vasoconstriction Ectotherms

A

when hot to retain heat

35
Q

Vasodilation

A

Increases conductance with environment

36
Q

Vasodilation Endotherm

A

when hot to release heat

37
Q

Vasodilation Ectotherm

A

when cold to increase heat gained from environment

38
Q

Internal insulation

A

Fat/blubber (internal insulation layer to slow rate of heat transfer)

39
Q

External insulation

A

Fur/feather (external insulation layer to slow rate of heat transfer)

40
Q

Piloerection

A

“fluffing” of fur/feather decreasing the rate of heat transfer by increasing thickness of insulation layer

41
Q

Dark fur

A

absorbs light and generates heat outside of insulation layer (easily lost to environment

42
Q

White fur

A

allows light to reach skin and generates heat inside of insulation layer (keeps arctic animals warmer)

43
Q

Sweating and panting

A

heat loss due to evaporation

44
Q

Cryoprotectants

A

molecules (glucose, glycerol) produced to lower freezing point

45
Q

Ice nucleating agents

A

antifreeze proteins prevents ice formation

46
Q

Shivering Thermogenesis

A

simultaneous action of antagonistic muscles generates heat without cause movement

47
Q

Non-Shivering Thermogenesis

A

molecular generation of heat

48
Q

Brown fat

A

special fat tissue loaded with special mitochondria (uses PMF for heat generation instead of ATP production)