Homeostasis + Regulation of body temperature

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What is homeostasis?
Maintenance of a constant internal environment
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Why is it important to maintain a constant water potential?
Otherwise cells could shrink or expand as a result of water entering/leaving due to osmosis.
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How is a constant water potential achieved?
By maintaining a constant blood glucose concentration
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What is a set point?
Normal level at which system operates
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What is a receptor?
Something that detects changes from the set point
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Describe the role of a controller
Coordinates info from various receptors and sends them to effectors.
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What does an effector do?
Brings about changes which return system to set point
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What is the role of the feedback loop?
To inform the receptor of changes to the system brough about by the effector
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Name 3 ways in which heat can be gained from the environment
Conduction, convection and radiation
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What does it mean if an animal is an ectotherm?
They gain most of their heat from the environment so their body temperature fluctuates with that of the environment.
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Name 3 ways in which lizards maintain their body temperature
They seek shelter to avoid overheating; they press themselves against the ground for warmth; they change colour (dark-absorb heat, light-reflect heat)
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What does it mean if an animal is an endotherm?
They gain most of their heat from internal metabolic activities
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Name 3 things endotherms do to gain heat in a cold environment
Vasoconstriction, shivering, raising of hair, decreased sweating, increased metabolic rate etc.
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What happens during vasoconstriction?
Diameter of arterioles near surface of skin is made smaller so blood entering skin passes beneath insulating layer of fat and loses little heat to the environment
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How does raising hairs increase heat gain?
A thick layer of still air is trapped next to the skin which improves insulation
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Name 3 things endotherms do to lose heat in a warm environment
Vasodilation, increased sweating, lowering of body hair, sheltering etc.
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What happens during vasodilation?
Diameter of arterioles near surface of skin increases allowing warm blood to pass close to the skin surface through the capillaries, radiating heat from the body.
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How does sweating cool animals down?
Heat energy is used to evaporate the water from the skin
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How does the water evaporate in hairy animals?
It evaporates from the tongue and mouth during panting
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What contains the thermoregulatory centre?
Hypothalamus
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What is the heat gain centre activated by?
Fall in blood temperature
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What is the heat loss centre activated by?
Rise in blood temperature
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What measures skin temperature?
Thermoreceptors in the skin
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Why is it important that the hypothalamus receives information about the external temperature as soon as possible?
So that the animal can make the decision to lose or gain heat before there is an effect on the core temperature
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Other cards in this set

Card 2

Front

Why is it important to maintain a constant water potential?

Back

Otherwise cells could shrink or expand as a result of water entering/leaving due to osmosis.

Card 3

Front

How is a constant water potential achieved?

Back

Preview of the front of card 3

Card 4

Front

What is a set point?

Back

Preview of the front of card 4

Card 5

Front

What is a receptor?

Back

Preview of the front of card 5
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