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BIOL 366 > Lecture 27- Animal Adaptations III > Flashcards

Lecture 27- Animal Adaptations III Flashcards

1
Q

What problems do the brids and mammals face when they remain active throughout the winter?

A
  • Must maintain narrow range of body temperatures needed to be maintain or you get denaturing of enzymes
  • Maintain body temperature much higher than air temperature
  • Must produce enough metabolic heat to offset to cold air
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2
Q

What is conduction?

A

Loss of heat through physically touching something (heat transferred to the ground)

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3
Q

What is convection?

A

Loss of heat to a water or a gas

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4
Q

What is radiation?

A

Heat that is always given off by some sort of heat source

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5
Q

What is Evaporation?

A

Transfer of liquid to a gas (occurs through respiration)

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6
Q

What are the four ways that contribute to energy loss?

A
  1. Conduction
  2. Convection
  3. Radiation
  4. Evaporation
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7
Q

How is heat loss from a small homeotherm?

A
  • Losing heat from the core body
  • Cant store heat in the body
  • Conduction
  • Convection
  • Radiation
  • Evaporation
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8
Q

What are some assumptions of heat loss?

A
  • Latent heat exchange is small in most homeotherms
  • Total heat loss from outer surface = heat conducted from the core of the animal to the outside surface
  • Heat cannot be stored on the surface of animals
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9
Q

Describe total heat loss

A
  • Total heat loss is a function of the conductivity of the general thermal conductivity and the surface area exposure, so how much of the animal is being exposed to heat loss to occur on
  • Relationship between temperature gradient and distance between the core and the outside air
  • How much distance does the thermal energy need to travel from the core
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10
Q

How to maintain a constant metabolic rate?

A
  • Decreasing thermal conductivity
  • Decreasing surface area exposed
  • Increasing thickness of insulating layer
  • Modifying microclimate
  • Nightly state of torpor
  • Solitary mammals can group together
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11
Q

How do you increase the thickness of insulating layer?

A
  • Increasing distance to core
  • Add fat
  • Erection of hairs
  • Fluffing of feathers (trapping air)
  • Thicker hair
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12
Q

How do you modify the mciroclimate?

A
  • Build nest of insulating materials or go underground where there’s less wind
  • Reduces the different between body temperature and air temperature
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13
Q

Whats an example of mammals grouping together?

A

Beaver lodges can be 35C warmer than outside air temperature, muskrats live in the beaver lodges, they bring in food and share the food, its a symbiotic interaction

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14
Q

How to Taiga Wolves survive the winter?

A
  • Nests of 5-10 taiga wolves
  • Never completely vacated so foraging animals return to warm nests
  • Animals also huddle in the nest
  • Nests about 15-20cm underground
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15
Q

What is a subnivean environment?

A

Habitat under the snow where small mammals will live in winter

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16
Q

What are the impacts of snow on small and larger mammals?

A
  • Larger = must adapt behaviour, feeding habits (harder to find food)
  • Smaller = can exploit snow to reduce thermal loss
17
Q

What are some benefits to snow?

A
  • Snow is a good insulator
  • Fluffy snow has a lot of air trapped in it and contains a warm microclimate in it
  • Barrier from dry, cold and windy air
  • Under snow = humid, warm and stable
  • Can form a crust on top of the snow that provides better protection from the cold
18
Q

What type of animals use subnivan environments?

A

Small mammals and invertebrates
(birds can burrow in the top layer of the snow

19
Q

At some point animals must ______

A

Must increase metabolic rate to balance heat loss (switch from physical to physiological changes)

20
Q

What is the LCT?

A
  • Lower critical temperature
  • Temperatur at which a change in physical to physiological adjustments is necessary
21
Q

What takes over when you go below the LCT?

A

Physiological thermoregulation takes over (get change in metabolic rate)

22
Q

What is the thermal neutral zone?

A

The area in which you can still make physical adjustments

23
Q

LCT varies based on?

A

Varies based on species and body size (larger body size has more leeway in reaching LCT)

24
Q

What is non-shivering thermogenesis?

A

Heat production from burning brown fat

25
Q

Secretion of ____ due to cold stimulates heat production in brown fat cells

A

Noradrenaline

26
Q

Why brown fat?

A

More mitochondria = higher rate of O2 consumption and heat produced and highly vascularized

27
Q

When is there an increase in brown fat and what causes it?

A

Accumulation occurs in early fall because of the decreasign day length and low temperatures (photoperiod and temperature)

28
Q

Difference between white and brown fat?

A
  • Brown fat much more granular and small
  • Highly vascularized
  • Heat dirrectly into the blood
  • More mitochondria
29
Q

The placement of brown fat is placed strategically to warm what up first?

A

To heat up the core first

30
Q

What part of the brain gets triggered by temperature drops to release noradrenaline?

A

Hypothalamus

31
Q

What happens to adipocytes for winter?

A
  • Animals increase lipid storage
  • Formation of additional adipocytes
  • Enlarging adipocytes
32
Q

Arctic animals have more _____

A

Adipocytes

33
Q

What are some natural obese animals?

A
  • Polar bear
  • Arctic fox
  • Caribou
  • Muskoxen
34
Q

What is shivering thermogenesis?

A

Rapid muscle activity that generates heat, this is critical last effort

35
Q

What are some problems with appendages?

A
  • Must be kept supplied with oxygen
  • Must be kept warm by circulating blood through them
  • Must avoid excess heat loss
36
Q

How to animals in the north avoid issues with appendages?

A
  • Shorter limbs
  • Utilize countercurrent heat exchange
37
Q

How does countercurrent heat exchange work?

A

Heat from arteries is transferred to veins

38
Q

Who uses nasal microcirculation and what is it?

A
  • Caribou
  • High density of capillaries in nose that absorbs heat before exhalation and it heats the incoming air
39
Q

What are some trade-offs between activity and avoidance?

A
  • Freeze tolerance or avoidance
  • Modified activity, changes in BMR
  • Increased insulation, brown fat
  • Countercurrent heat exchange

BIOL 366 (33 decks)

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