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Biology 241 > Thermoregulation > Flashcards

Thermoregulation Flashcards

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1
Q

What is homeostasis?

A

The regulation of an internal environment in the face of changes in the external environment. This does not imply that a “constant” internal environment. An organism can change its behaviour or metabolism to maintain its internal environment within an acceptable range.

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2
Q

What parameters does an organism control and keep within a narrow range?

A

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

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3
Q

What is a negative feedback mechanism?

A

A change in a variable triggers a response that opposes the change

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4
Q

Name and describe the components of a negative feedback mechanism.

A

Stimulus: external or internal change in a regulated factor
Sensor: detects the change in condition
Integrator: compares condition to its set point and activates the Effector
Effector: a physiological change that returns factor to set point

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5
Q

What is a positive feedback mechanism?

A

A change in a variable triggers a response that amplifies the change

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6
Q

Name and describe the components of a positive feedback mechanism in relation to birth.

A

Sensor: “sensory receptors” in cervix
Integrator: pituitary gland releases oxytocin
Effector: oxytocin causes the uterus to contract (and cervix to dilate) putting more pressure against sensors

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7
Q

Why does thermoregulation matter?

A

Regulating internal body temperature impacts energy budgets.
Ambient temp determines how much energy is spent regulating body temp

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8
Q

Describe body heat in endotherms.

A
  • Heat is generated by metabolism
  • Heat can be exchanged with the environment by conduction, evaporation, and radiation
  • Body temp can be regulated by changing the rate of heat gain and loss
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9
Q

What is conductance?

A

The rate of heat exchange

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10
Q

What is convection?

A

Air/liquid for heat transfer

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11
Q

What is conduction?

A

Direct contact heat transfer

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12
Q

What is evaporation?

A

Loss of heat when water is changed from liquid to gas

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13
Q

What is a homeotherm?

A

Maintains “constant” body temperature independant of ambient temperature

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14
Q

What is a heterotherm?

A

Body temperature fluctuates with ambient temperature

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15
Q

What is an endotherm?

A

Uses metabolism to generate body temperature

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16
Q

What is an ectotherm?

A

Gets body temperature from environment. Also generates metabolism heat but doesn’t keep it

17
Q

What is a heterothermic endotherm?

A

Change body temperature seasonally (torpor, hibernation)

18
Q

What is an heterothermic ectotherm?

A

Behavioural: move between sun and shade
Physiological: adjust metabolic rates based on ambient temperature

19
Q

What is a homeothermic endotherm?

A

Behavioural: seek cool or warmth
Physiological: sweating, panting, shivering

20
Q

What is a homeothermic ectotherm?

A

Seek or live exclusively in stable environments or microhabitats

21
Q

Do larger organisms have conductance?

A

Yes, however they have lower conductance because of their smaller surface area to volume ratio

22
Q

What is regional heterothermy?

A

Animals with different temperatures in different parts of their body

23
Q

Do endotherms have higher mass-specific RMR than endotherms?

A

Yes.
Also, as body mass increases, mass-specific RMR decreases

24
Q

What is the slope on a graph of an endotherm?

A

0 unless at extremes, which will then reflect the denaturation of proteins and enzymes

25
Q

What is the slope on a graph of an ectotherm?

A

1, representing a 1:1 ratio

26
Q

Describe strategies for homeothermic endotherms below the thermoneutral zone.

A

Shivering, vasoconstriction (less blood to periphery), piloerection (increasing the depth of fur), decreasing surface area, decreasing exposure (huddling, burrowing)
THERMOGENESIS!

27
Q

Describe strategies for homeothermic endotherms above the thermoneutral zone.

A

Panting, vasodilation, sweating, increasing surface area, decreasing exposure (to the sun)
ACTIVE COOLING!

28
Q

What is low conductance an adaptation for?

A

Heat retention

29
Q

What is high conductance an adaptation for?

A

Heat loss

30
Q

How can animals minimize energy expenditure due to temperature?

A

By moving; changing exposure (seek/avoid sun and wind), grouping, migration, and dormancy

31
Q

What is torpor?

A

A dormancy strategy that reduces energy use and metabolic rate to stay warm; especially during winter when food is scarce, or during a drought

32
Q

What is hibernation?

A

Another dormancy strategy usually present in small mammals (smaller surface area to volume ratio therefore easier for body temp to fluctuate).
- Stores lipids before hibernation to metabolize when they wake up
- Results in a drop to near ambient temp
- Awake 1-2 days periodically to release toxic waste (like urine)

33
Q

What are some strategies to optimize heat exchange with environment to attain an optimal body temperature?

A
  • Acclimation
  • Blood flow
  • Insulation
  • Fur length and colour change
  • Sweating/panting
  • Cryoprotectants
  • Shivering thermogenesis
  • Non-shivering thermogenesis
34
Q

What is acclimation?

A

Changes to physiological processes that respond to typically seasonal temperature changes. Cells, enzymes, and proteins alter optimum temperature for performance.
- Animals produce more enzyme to compensate for lower efficiency
- Cell membranes have changes that alter the viscosity
- Enzymes change their conformation to be more efficient

35
Q

What is vasoconstriction in relation to conductance?

A

Vasoconstriction: decreases conductance with the environment
Endotherms: when cold to retain heat
Ectotherms: when hot to retain heat

36
Q

What is vasodilation in relation to conductance?

A

Vasodilation increases conductance with the environment
Endotherms: when hot release heat
Ectotherms: when cold to increase heat gained from environment

37
Q

What is insulation?

A

Internal or external strategies to slow rate of heat transfer.
Internal: fat/blubber
External: Fur/feathers

38
Q

Discuss fur colouration.

A

Dark fur: absorbs light, generates heat outside insulation, heat lost to environment more easily by convection

Light fur: allows light to reach skin, generates heat inside insulation layer, skin stays warmer as fur protects its loss, hollow hairs let radiation transmit down the shaft

39
Q

What are cryoprotectants?

A

molecules (glucose, glycerol) produced to lower freezing point. Used by ectotherms and prevent crystallization

Biology 241 (6 decks)

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