Answer:
The skin contains many blood capillaries and sweat glands ,the sweat glands secrete sweat when it is hot.when the sweat evaporates from the skin it cools the body.thermoregulation by the skin occurs through dilation and constriction of the blood vessels.when the bodies temperature raises,the blood vessels carry heat in the blood to the skin.the blood capillaries dilate become wider so that more heat can be lost to the environment.this is called vasodilation.when the outside temperature is low,the blood capillaries constrict become narrower so that less blood flows to the surface of the skin.therefore less heat is lost to the environment this is called vasoconstriction.
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