IGCSE Biology glossary
Vasoconstriction
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Definition
The narrowing of arterioles near the skin surface in response to cold. This reduces blood flow close to the skin surface, decreasing heat loss by radiation from the blood to the environment and helping to maintain core body temperature.
What to include in an exam answer
It is the arterioles that constrict, not the capillaries. Blood is diverted away from the skin surface to deeper tissues. Pair with vasodilation as the opposite response in hot conditions.
Example in context
Explain how vasoconstriction helps maintain body temperature in cold conditions (2 marks): Arterioles near the skin surface narrow, reducing blood flow to the surface capillaries. Less heat is lost from the blood by radiation through the skin, helping to conserve body heat.
Related syllabus topic
Coordination & responseRelated terms
- Homeostasis
- Negative feedback
- Tropism
- Reflex arc
- ADH
- Insulin
- Glucagon
- Adrenaline
- Synapse
- Neurone
- Sensory neurone
- Motor neurone
- Relay neurone
- Receptor
- Effector
- Cornea
- Iris
- Lens
- Retina
- Optic nerve
- Accommodation
- Type 1 diabetes
- Type 2 diabetes
- Hormones
- Endocrine gland
- Auxin
- Thermoregulation
- Vasodilation
- Sweating