What happens when we blush?

The flow of blood to the skin is regulated through many very very small blood vessels. They act as bridges between the arteries-which bring blood from the heart-and the veins, which take the blood back to the heart. Each of these tiny blood vessels has its own tiny nerve to open and close it. Therefore the nerve system controls the flow of blood to the surface of the skin.
When a blush spreads over the face, it is because some of the nerves have turned on the tap controlling the blood supply. The nerves may turn on the tap from anger, from fright or from shame or some other emorion like LOVE... And these very same emotions may also cause the nerves to turn the tap off. This cuts off the supply of blood to the skin, and the face truns pale, or white.