Blutgefäß-Thermoregulation: Vasodilatation gibt Wärme ab, Vasokonstriktion spart sie

Correction: The original statement was reversed. To lose heat, cutaneous vessels dilate (widen), increasing blood flow near the skin surface, allowing radiative/convective heat loss. To conserve heat, vessels constrict (narrow), shunting blood to the core.

This is controlled by the hypothalamus via sympathetic nervous system. In heat: vasodilation + sweating. In cold: vasoconstriction + shivering.