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BI310 > Temperature relations of animals > Flashcards

Temperature relations of animals Flashcards

1
Q

What is an endotherm?

A

An animal that generates its own body heat e.g., birds & mammals

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2
Q

What is an ectotherm?

A

An animal that depends almost entirely on ambient heat sources e.g., invertebrates, fish, amphibians, reptiles

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3
Q

What is a heterotherm?

A

An animal whose heat depends on their regional environments

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4
Q

What is a poikilotherm?

A

Animal whose body temperature fluctuates with changes in ambient temperature

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5
Q

What is a homeotherm?

A

Animal who regulates body temperature close to a set point
Nearly all endotherms are homeotherms

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6
Q

What endotherm does not regulate about a set point?

A

Naked mole rate which is poikilothermic lives in a stable environment

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7
Q

The rate of change of body heat depends on the rates of which
three factors

A
  • Heat production through metabolic means
  • Heat gain from environment
  • Heat loss to environment
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8
Q

What is basal metabolism?

A

The basic metabolic processes used to produce heat

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9
Q

What is the metabolic rate?

A

The sum of all energy-requiring biochemical reactions over a given time interval

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10
Q

What is the basal metabolic rate (BMR)?

A

The basal metabolic rate
(BMR) is that of an animal that
is at rest, is not digesting, and
is not experiencing stress

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11
Q

What factors influence heat production?

A
  • Behavioural mechanisms e.g., exercise
  • Autonomic mechanisms e.g., accelerated metabolism of energy reserves
  • Acclimatization (longer term): increase BMR
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12
Q

What are the 4 methods of heat transfer?

A
  • Conduction
  • Convection
  • Radiation
  • Evaporation
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13
Q

What is conduction and what is it affected by?

A
  • Heat transfer between objects in direct contact with each other
  • It is affected by surface area and temperature gradient
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14
Q

What is convection?

A

Transfer of heat contained in a gas or liquid by the movement of the gas or liquid.
- Accelerates heat transfer
- In water it causes rapid cooling

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15
Q

What are the methods of heat transfer?

A
  1. Radiation- no direct contact between bodies
  2. Evaporation- evaporation of liquid needs heat, lost to surface
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16
Q

What does the rate of heat transfer between a body and the
environment depends on?

A

-Surface area: surface area/g tissue decreases with
increase in body size, therefore small animals lose and
gain heat faster than large ones
- Temperature difference: the closer the body temperature
to that of the environment the less heat is lost or gained
- Heat conducting properties of animal’s surface (“specific
heat conductance”)

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17
Q

What are the heat conducting properties of poikilotherms?

A
  • High heat conductance
  • Gain or lose heat rapidly,
  • Stay close to environmental temp
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18
Q

What are the heat conducting properties of homeotherms?

A
  • Insulation reduces heat transfer
  • Feathers, fur or blubber
  • Fur & feathers trap air; (poor heat conductor)
19
Q

How do autonomic processes regulate heat exchange?

A
  • Modify blood flow to vertebrate skin
  • Fluffing of hair/feathers (more air increases insulation)
  • Sweating/ panting to increase evaporative cooling
20
Q

What long term adaptions regulate heat exchange?

A

Changes in thickness of fur/blubber

21
Q

How does behaviour regulate heat exchange?

A
  • Animals move to area with suitable temperature e.g., sun or shade
  • Posture: curl tightly to reduce heat
    exchange, spread out to maximise it
22
Q

Factors influencing heat production
Regulation of heat exchange

A

See slide 20 of temperature relations lectures

23
Q

What do temperature relations of ectotherm depend on?

A
  • Heat from environment
24
Q

Behavioural thermoregulation of reptiles

A

Reptiles typically regulate their body temperature behaviourally, by moving to sun or shade to absorb more or less heat

25
Q

What are the advantages of ectothermy?

A
  • Can invest larger proportion of
    energy in growth and reproduction
  • Need less food.. less time foraging, more time hiding from predators
  • Need less water (do not require
    water for evaporative cooling
26
Q

What are the disadvantages of ectothermy?

A
  • Dependent on environment
  • Sustained high levels of activity
    not possible
27
Q

Give an example of heterothermy in insects

A
  • In locusts, moths and butterflies
  • Warm flight muscles to 40oC before take-off by shivering movements of
    flight muscles
  • Thorax is insulated
28
Q

How do bees regulate temperature?

A
  • Hive is at constant temp of 35 degrees: fan wings to evaporate water for cooling
    -Swarms: shivering for warmth, swarm as dense shape reduces airflow and conserves heat
29
Q

An example of regional heterotherms in fish

A

Tuna. maintain core temperature above ambient

30
Q

What constant core body temperature do endotherms maintain?

A

37-41 degrees

31
Q

What is the ambient temperature in humans?

A

20 degrees

32
Q

What is the core temperature in humans?

A

37 degrees

33
Q

What are some characteristics of homeothermic endotherms?

A
  • High basal metabolic rate (BMR)(generates heat)
  • Heat-conserving mechanisms
  • Heat-dissipating mechanisms
  • Maintain stable core body temperature over a wide range of environmental temperatures
34
Q

What is the thermal neutral zone?

A

The body temp maintained by changing conductance of body surface
- no extra energy needed
- bound by upper & lower critical limits UCT & LCT

35
Q

Where is the zone of metabolic regulation

A

Cold ambient temp- below LCT
- By thermogenesis

36
Q

Where is the zone of
active heat dissipation

A

At warm ambient temp- above UCT
- By increasing evaporationg cooling

37
Q

How is temperature regulated at moderate temperatures?

A
  • Adjust heat transfer (gain/loss from environment) e.g.
  • Fluff hair/feathers (pilomotor response)
  • Postures to conserve/dissipate heat
  • Adjust blood flow to periphery (vasomotor response)
38
Q

What is the vasomoter response?

A

It is the change in blood flow to skin help regulate heat conductance of body surface
- Response to cold: vasoconstriction
Response to warmth: vasodilation

39
Q

How is temperature regulated below critical levels (below LCT)?

A

Increase heat production above
basal levels (thermogenesis) by
converting stored energy
reserves into heat

40
Q

What occurs during shivering?

A

– Contraction of groups of antagonistic muscles
– No useful physical work
– Chemical energy from hydrolysis of
ATP released as heat

41
Q

What happens during non-shivering thermogenesis?

A

– Metabolism of fat (incl. brown fat)
to produce heat

42
Q

What is brown fat?

A

-It is a special store between
neck and shoulders of some mammals
-It has adapted for rapid massive
heat production

43
Q

What are the characteristics of brown fat?

A
  • many mitochondria
  • fat-metabolizing enzyme systems
  • many blood vessels – rapidly transfer heat to rest of body
  • activated by sympathetic nervous system
  • important in animals emerging from hibernation
  • increases during cold-acclimation

BI310 (7 decks)

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