Ever wonder why we sweat or shiver?

When it's hot our blood vessels widen at our skin surface, allowing more blood to flow to the surface so more heat is lost by radiation. This is called vasodilation. Our sweat glands also produce more sweat, so that it evaporates and this cools you down!

When it's cold our blood vessels close up at our skin surface. Cutting down the flow of blood to the surface, so less heat is lost by radiation. Sweat glands stop producing sweat. And our muscles start to contract quickly, in order to produce extra heat that warms your body. This is why we shiver!

Want to learn more about vasodilation?! Check out this blog:

http://vasodilationbuzz.blogspot.com/