Final answer:
Frostbite is caused by peripheral vasoconstriction in response to cold temperatures, which reduces blood flow to the extremities to preserve core body warmth.
Step-by-step explanation:
Frostbite results from peripheral vasoconstriction due to exposure to cold temperatures. When the body is exposed to cold, it initiates vasoconstriction to reduce blood flow to the extremities, like the hands and feet, to prevent the blood from cooling too much and to help the body's core maintain warmth.
This extreme vasoconstriction in the extremities can lead to frostbite as the tissues do not receive enough warm blood to stay functional. Frostbite can cause permanent tissue damage and, in severe cases, may lead to gangrene and necessitate amputation.
Vasodilation, on the other hand, is the process where blood vessels widen to increase blood flow to the skin to allow for radiation and evaporative heat loss, which is not the case in frostbite.