Vasoconstriction

Blood vessels supplying the skin constrict, so less blood flows close to the surface. This vasoconstriction reduces energy transfer from the blood through the skin to the environment. Sweating stops, so less energy is lost through evaporation.

At the same time, vasoconstriction reduces heat loss. The small arteries, or arterioles, supplying capillaries near the skin surface become narrower. Less warm blood flows through those capillaries, so less heat is transferred from the blood through the skin to the surroundings.

Vasoconstriction also occurs. The arterioles supplying capillaries near the skin surface narrow, so less warm blood flows through them. Less energy is brought close to the surface and less is transferred to the surroundings.

The arterioles supplying the surface capillaries narrow. This vasoconstriction reduces blood flow close to the surface, so less thermal energy is transferred from the blood to the surroundings. Blood continues to flow to the skin; its flow near the surface is reduced rather than completely stopped.