Homeostasis and Thermoregulation Flashcards

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1
Q

What is the definition of homeostasis?

A

The maintenance of a stable equilibrium in the conditions inside of the body, with small fluctuations over a narrow range of conditions.

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2
Q

What is negative feedback?

A

When there is a stimulus, effectors work to reverse the change and restore conditions to their optimum level.

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3
Q

What is positive feedback?

A

When there is a stimulus, the effectors are stimulated so that it can reinforce that change and increase the response.

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4
Q

How does the body react to stimuli?

A

Stimulus - receptor - cell communication - effector - response

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5
Q

What is thermoregulation?

A

Maintaining a relatively constant core body temperature.

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6
Q

What causes organisms to heat up and cool down? (5)

A
  • Exothermic chemical reactions
  • Latent heat of evaporation
  • Radiation
  • Convection
  • Conduction
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7
Q

What is an ectotherm? (2)

A
  • Organisms that use their surrounding to warm their bodies.

- Core body temperature is heavily dependent on environment

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8
Q

What is special about ectotherms in water?

A
  • They don’t need to thermoregulate

- High heat capacity of water means the external environment doesn’t change

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9
Q

What is an endotherm? (4)

A
  • Organisms that rely on metabolic processes to warm them up
  • Usually maintain stable core body temperature
  • Can survive in a wide range of environments
  • Need more food for energy for metabolic reactions
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10
Q

What are some behavioral responses that ectotherms have developed? (8)

A
  • Basking in sun
  • Orientate their bodies - max. SA exposed to sun
  • Conduction - pressing bodies to hot ground or rocks
  • Contract muscles and vibrate to increase cellular metabolism
  • Seeking shade
  • Hiding in cracks in rocks
  • Digging burrows
  • Minimise movement
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11
Q

What are some physiological responses to warming in ectotherms? (2)

A
  • Darker skin - absorb more heat

- Alter heart rate to increase/decrease metabolic activity

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12
Q

How do endotherms detect change in internal environment? (2)

A
  • Peripheral temperature receptors in the skin detect surface temperature
  • Temperature receptors in the hypothalamus detect the temperature of the blood deep in the body
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13
Q

What is the advantage of having temperature receptors in both the skin and the hypothalamus? (3)

A
  • Gives great sensitivity
  • Allows it to respond to changes
  • Pre-empt possible problems that might result in the change of the external environment
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14
Q

What are some behavioural responses for endotherms? (3)

A
  • Everything for ectotherms
  • Become dormant in the winter (hibernate) or summer (aestivation)
  • Humans wear clothes, have houses built
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15
Q

What are some physiological adaptations in endotherms?

A
  • Peripheral temperature receptors
  • Thermoregulatory centres of the hypothalamus
  • The skin
  • Muscles
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16
Q

How do humans use vasodilation to cool down?

A
  • Arterioles near the surface of the skin dilate when too hot
  • Blood forced into the capillaries near the skin
  • Skin flushes and cools due to