Describe when and how the skin reduces loss of heat in the body

Vasoconstriction occurs when the blood vessels in the skin narrow. This reduces the blood flow to the surface of the skin, meaning less heat is carried from the body's core to the extremities where it can be lost to the environment. This process is controlled by the nervous system in response to cold temperatures.

Insulation is provided by the layer of adipose tissue (fat) beneath the skin. Fat is a poor conductor of heat, so it acts as a barrier, slowing down the rate at which heat escapes from the body. Additionally, hair on the skin can trap a layer of air, which also acts as an insulator, though this effect is less significant in humans than in animals with thicker fur.