Why do we blush when we are embarrassed?

I know blushing is blood flow to the cheeks, but why does it happen?Why do we blush when we are embarrassed?
http://www.essortment.com/all/blushwhydo鈥?/a>Why do we blush when we are embarrassed?
There is evidence that the blushing region is anatomically different in structure. The facial skin, for example, has more capillary loops per square millimeter and generally more vessels per unit volume than other skin areas. In addition, blood vessels of the cheek are wider in diameter, are nearer the surface, and visibility is less diminished by tissue fluid.





Blushing begins with an emotion鈥攗sually one associated with self-consciousness. Our adrenal glands produce adrenaline that binds to the surface of responsive cells. This causes an enzyme called adenylyl cyclase to activate, which, in turn, causes the level of cyclic AMP to increase. Cyclic AMP is a messenger molecule that transmits the adrenaline signal within the cell. This increase in cyclic AMP levels directly causes the dilation of blood vessels.