BRAINCAKEVasoconstriction
Vasoconstriction is the narrowing of the arterioles that supply the capillaries near the skin surface. It is a response to a fall in core temperature.
When the heat gain centre in the hypothalamus is activated, more impulses are sent along sympathetic nerves to the arterioles in the skin. The ring of smooth muscle in their walls contracts, narrowing the lumen. At the same time the shunt vessels (arteriovenous shunts) dilate, so blood is diverted from the arterioles straight to the venules, deeper in the skin.
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Key terms in this lesson
- frostbite
- Damage to tissue in the extremities caused by prolonged vasoconstriction starving it of oxygen in the cold.
More in Homeostasis
- Keeping Cool
- Keeping Warm
- Control of Core Body Temperature
- Vasodilation
- Adaptations for Cold Environments
- Adaptations for Hot Environments
- Cooling The Brain
- Behavioural Control of Body Temperature
All 41 lessons in Homeostasis · All Edexcel A-level Biology topics