5.1.1 Communication and homeostasis Flashcards

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1
Q

What is an ectotherm?

A

Animals which rely on the environment to warm their bodies and maintain their core temperature

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2
Q

What is an endotherm?

A

Animals that rely on their metabolic processes to warm their bodies and maintain core temperature

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3
Q

What is homeostasis?

A

Regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes (normally through negative feedback)

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4
Q

What type of response involved in temperature control is more common for ectotherms?

A

Behavioural

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5
Q

What are the behavioural responses to raise body temperature of ectotherms?

A
  • Bask in the sun
  • Orientate body to maximise SA exposed to sun
  • Pressing body to warm ground
  • Maximise movement to increase metabolic heat
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6
Q

What are the behavioural responses to lower body temperature of ectotherms?

A
  • Seek shelter in shady areas with water
  • Orientate body to minimise SA exposed to sun
  • Press body against cool ground
  • Minimise movements to reduce metabolic heat
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7
Q

What are the physiological responses of ectotherms? (Less common)

A
  • Dark colours absorb more radiation
  • Alter heart rate to increase or decrease metabolic rate
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8
Q

Why can ectotherms survive in habitats with limited food supplies?

A

Require less food than endotherms because they use less energy in regulating body temperature

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9
Q

Why do aquatic ectotherms have less difficulty in maintaining internal body temperature?

A

Water has a high specific heat capacity and so temperatures are constant

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10
Q

What type of response involved in temperature control is more common for endotherms?

A

Physiological

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11
Q

What is the physiological response to lower body temperature in endotherms? (Heat loss centre)

A
  • Vasodilation
  • Sweating
  • Hair erector muscles relax
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12
Q

How does vasodilation work?

A
  • Arterioles near surface of skin dilate
  • Blood vessels (shunt vessel) deeper within skin constrict
  • Blood flow to surface increased
  • More heat radiates from surface
  • Skin flushes and cools
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13
Q

How does increased sweating help to endotherms to cool down?

A

Sweat evaporates from skin and transfers heat
(Less effective in humid environment due to reduced concentration gradient)

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14
Q

How does flattening of hair help endotherms to cool down?

A

Avoids insulating layer of air from being trapped

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15
Q

What are the anatomical adaptations of animals in warm climates?

A
  • Large SA to maximise heat loss
  • Pale fur or feathers to reflect radiation
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16
Q

What is the physiological response to raise body temperature in endotherms? (Heat gain centre)

A
  • Vasoconstriction
  • Shivering
  • Hair erector muscles contract
17
Q

How does vasoconstriction work

A
  • Arterioles near surface of skin constrict
  • Blood vessels (shunt vessel) deeper within skin dilate
  • Blood flow to surface reduced
  • Less heat radiates from surface
  • Skin pales and retains heat
18
Q

How does shivering help to warm an endotherm?

A

Metabolic heat from exothermic reactions causing this relaxation and contraction warms body

19
Q

What are the anatomical adaptations of endotherms in cold climates?

A
  • Small SA
  • Thick layer of insulating fat under skin
  • Hibernation
20
Q

What do peripheral temperature receptors do?

A

Detect changes in surface temperature - most likely to be affected by external conditions

21
Q

What do hypothalamus temperature receptors do?

A

Detect changes in temperature of blood deep in body - most likely to be affected by internal conditions

22
Q

What are the two control centres in endotherms?

A

Heat loss centre
Heat gain centre

23
Q

What does negative feedback do?

A

Reduces the initial effect of the stimulus

24
Q

What does positive feedback do?

A

Enhances the initial effect of stimulus

25
Q

What is paracrine signalling?

A
  • Between cells that are close together
  • Signalling molecule e.g. glycoproteins
26
Q

What is endocrine signalling?

A
  • Between cells that are far apart
  • Signalling molecule e.g. hormones