Under what circumstances do people blanch vs. blush?



I hear that both happen due to the fight-or-flight response. How can this be? Was I misinformed?

In: Biology

Blanching is caused by vasoconstriction- your blood vessels in the skin contract to force blood to your essential organs and muscles where it is most needed typically in a fight or flight situation. This is caused by adrenaline and cortisol release – 2 hormones which the brain triggers in stress.

Blushing is a little more complex and not fully understood. It occurs mainly in emotionally stressful situations (embarrassment etc), and is hypothesised to be a rebound of the typical fight or flight situation where a physical response is not possible as described causing vasodilation- blood vessels expanding.

Your body is not a “one size fits all” kind of machine.

Adrenaline causes both vasoconstriction and vasodilation depending on where in the body you are talking about. The face is one of those complicated areas where the brain might decide to constrict or dilate the blood vessels – or both!

Vasoconstriction causes you to pale as blood is routed away from your skin and towards more important areas like your lungs, heart, and skeletal muscles.

But vasodilation of the capillaries in your cheeks will cause you to blush. This is an important feature if you are about to run or fight for your life – this is how you lose excess heat. Your arms and legs might blush, too, and you might start to sweat in anticipation of frantic exercise. Excess heat will kill you just as quickly as a lion if you don’t keep it under control, so your body will pull out all the stops to make sure you can get the hell out of dodge and not cook yourself in the attempt.