[Lauramalina]

Hence the phrase, "my blood is boiling" Anger makes your blood run hot which is why you get flushed when you're mad. Anger is not good for you as it turns your blood to acid and over time makes you sick.
Scientifically speaking....Your heart beats faster and it makes your body warmer just like when you have a good work out and your body releases heat at throught the easiest ways out of the body.