Why do people go red in the face, or blush?

When people get nervous, or they are caught out lieing or something, why do they go red in the face? My friend sometimes feels like her wants to faint, why is this?Why do people go red in the face, or blush?
When you're embarrassed, your body releases adrenaline. This hormone acts as a natural stimulant and has an array of effects on your body that are all part of the fight-or-flight response. Adrenaline speeds up your breathing and heart rate to prepare you to run from danger. It causes your pupils to grow bigger to allow you to take in as much visual information as possible. It slows down your digestive process so that the energy can be redirected to your muscles. All of these effects account for the jolt you feel when you find yourself embarrassed.Why do people go red in the face, or blush?
Blushing is part of the fight-or-flight response that all bodies have. It's part of the sympathetic nervous system. Something that makes one person blush may not make another person blush, but it's all the same feeling that makes a person blush or get red cheeks. ';When you're embarrassed, your body releases adrenaline. This hormone acts as a natural stimulant and has an array of effects on your body that are all part of the fight-or-flight response.'; Also from howstuffworks.com, ';Adrenaline also causes your blood vessels to dilate (called vasodilation), in order to improve blood flow and oxygen delivery. This is the case with blushing. The veins in your face respond to a signal from the chemical transmitter adenylyl cyclase, which tells the veins to allow the adrenaline to do its magic. As a result, the veins in your face dilate, allowing more blood to flow through them than usual, creating the reddened appearance that tells others you're embarrassed. In other words, adrenaline causes more local blood flow in your cheeks.'; Hope this helps.
i think its because all the blood goes to your face?