Flashcards · Biology · Homeostasis
Vasoconstriction and Vasodilation (Higher tier)
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What is vasodilation?
The widening of the blood vessels in the skin.
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What is vasoconstriction?
The narrowing of the blood vessels in the skin.
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When does vasodilation happen?
When the body is too hot.
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When does vasoconstriction happen?
When the body is too cold.
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What does vasodilation do to heat loss?
Increases it.
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What does vasoconstriction do to heat loss?
Reduces it.
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What makes the vessels change diameter?
Muscles in the vessel walls, controlled by impulses from the hypothalamus.
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Where is heat lost from?
The blood close to the surface of the skin.
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What colour is the skin in vasodilation?
Redder.
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What colour is the skin in vasoconstriction?
Paler.
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Which part of the brain controls the response?
The hypothalamus.
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What is the normal body temperature?
About 37 °C.
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Name two other responses when too hot.
More sweat, and the hairs lie flat.
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Name two other responses when too cold.
Shivering, and the hairs stand up.
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Does the blood vessel move towards the skin?
No, it changes in diameter.
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Common mistake about vasoconstriction?
Saying that it warms the skin. It makes the skin cooler, because less blood reaches it.