What are the differences between dilation and constriction process?

Cooling and warming Heat and cold receptors are located in the skin. When the temperature of the body rises, the hypothalamus sends nerve signals which cause dilation of the blood vessels in the skin, allowing more blood to flow into the area, so that the excess heat carried by the blood can dissipate through the skin and into the environment. This is known as the dilation process of the integumentary system which results in cooling.

When the temperature of the body falls, the blood vessels in the skin constrict to minimize heat loss in to the environment. Passive heat loss is prevented and internal structures remain warm. This is known as the constriction process of the integumentary system which results in warming.