Which action conserves heat by reducing blood flow to the skin?

Which action conserves heat by reducing blood flow to the skin?

• A. Blood vessels dilate
• B. Sweat glands activate
• C. Arteries widen
• D. Blood vessels constrict

Answer: (D)

To conserve heat, the body reduces heat loss by limiting blood flow to the skin. When you’re cold, blood vessels in the skin constrict, narrowing the arterioles and sending less warm blood to the surface. With less blood at the skin, less heat escapes as radiation and convection, helping to keep the core temperature up. The other actions would do the opposite: dilating blood vessels or widening arteries increases skin blood flow and promotes heat loss, while activating sweat glands cools the body through evaporation.

To conserve heat, the body reduces heat loss by limiting blood flow to the skin. When you’re cold, blood vessels in the skin constrict, narrowing the arterioles and sending less warm blood to the surface. With less blood at the skin, less heat escapes as radiation and convection, helping to keep the core temperature up.

The other actions would do the opposite: dilating blood vessels or widening arteries increases skin blood flow and promotes heat loss, while activating sweat glands cools the body through evaporation.