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
Secretion of ____ due to cold stimulates heat production in brown fat cells
Noradrenaline
26
Why brown fat?
More mitochondria = higher rate of O2 consumption and heat produced and highly vascularized
27
When is there an increase in brown fat and what causes it?
Accumulation occurs in early fall because of the decreasign day length and low temperatures (photoperiod and temperature)
28
Difference between white and brown fat?
* Brown fat much more granular and small * Highly vascularized * Heat dirrectly into the blood * More mitochondria
29
The placement of brown fat is placed strategically to warm what up first?
To heat up the core first
30
What part of the brain gets triggered by temperature drops to release noradrenaline?
Hypothalamus
31
What happens to adipocytes for winter?
* Animals increase lipid storage * Formation of additional adipocytes * Enlarging adipocytes
32
Arctic animals have more _____
Adipocytes
33
What are some natural obese animals?
* Polar bear * Arctic fox * Caribou * Muskoxen
34
What is shivering thermogenesis?
Rapid muscle activity that generates heat, this is critical last effort
35
What are some problems with appendages?
* Must be kept supplied with oxygen * Must be kept warm by circulating blood through them * Must avoid excess heat loss
36
How to animals in the north avoid issues with appendages?
* Shorter limbs * Utilize countercurrent heat exchange
37
How does countercurrent heat exchange work?
Heat from arteries is transferred to veins
38
Who uses nasal microcirculation and what is it?
* Caribou * High density of capillaries in nose that absorbs heat before exhalation and it heats the incoming air
39
What are some trade-offs between activity and avoidance?
* Freeze tolerance or avoidance * Modified activity, changes in BMR * Increased insulation, brown fat * Countercurrent heat exchange