IGCSE Biology glossary
Vasodilation
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Definition
The widening of arterioles near the skin surface in response to heat. This increases blood flow close to the skin surface, increasing heat loss by radiation from the blood to the cooler environment and helping to cool the body down.
What to include in an exam answer
In hot conditions, arterioles dilate so more blood flows near the skin surface. More heat is lost by radiation. Combine with sweating (evaporation of water uses heat energy from the skin) for a complete answer.
Example in context
Explain how vasodilation helps cool the body (2 marks): Arterioles near the skin surface widen, increasing blood flow to surface capillaries. More heat energy is transferred from the blood to the environment by radiation through the skin, cooling the body.
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
- Vasoconstriction
- Sweating