Whether you trip down the stairs in public or accidently let out a burp in front of all your coworkers, blushing is a natural response to sudden self-consciousness. Blushing and embarrassment go hand in hand, but why are they so closely linked? Though scientists do not fully understand the psychology of blushing, the physical process is fairly straightforward.
Blushing from embarrassment is caused by the sympathetic nervous system, which is also responsible for activating the fight-or-flight response in stressful situations. Since the system is completely involuntary, these processes happen whether you think about them or not. When you feel embarrassment, your body releases adrenaline, which is what causes the sudden jolt you feel—adrenaline works as a natural stimulant, speeding up your breathing, increasing your heart rate, and dilating your pupils.
Vasodilation is the process of your blood vessels dilating as a response to adrenaline as well. When you are embarrassed, the veins in your face respond to signals from chemical transmitters called adenylyl cyclase. This allows more blood to flow through the veins in your face than usual, which creates the reddened appearance in your cheeks and lets others know that you are embarrassed.