Final answer:
In response to cold temperatures, blood vessels in the skin constrict to divert blood away from the skin's surface, conserving body heat.
Step-by-step explanation:
When exposed to cold temperatures, the blood vessels in the skin respond by undergoing vasoconstriction. This physiological process means that the blood vessels constrict, which effectively diverts blood away from the skin to reduce heat loss from the surface, thereby helping to conserve body heat. Vasoconstriction is in contrast to vasodilation, which occurs during warm conditions or during physical activities like skiing or running, allowing more blood to flow to the skin's surface aiding in heat loss.