Eli5: Why does irritated red skin ( sunburn for instance ) change back to its original color when pressure is applied ?

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Eli5: Why does irritated red skin ( sunburn for instance ) change back to its original color when pressure is applied ?

In: Biology

Sun burns are red to begin with because part of your body’s response to the burn is to send more blood to that area. When you apply pressure, you are temporarily cutting off blood flow. No blood = no red.

The redness of irritated skin is due to increased blood flow to the area. When you press on the skin the blood is forced out of the area from the increased pressure, turning it back to more its original color. This can also be done with normal skin, where pressure can push blood out and make it more pale even than normal.

It turns red because it is irritated and inflamed. When skin is irritated and inflamed like this, extra blood flows into it, this extra blood is there to start and bring nutrients for the healing process.

So it is the extra blood that causes that red color.

When you then press down on your skin, you momentarily push that extra blood out like your squeezing a sponge, and then it takes a second to flow back into the spot you just pressed down on. So for a moment you don’t have the extra blood causing a red color, so it’s just your normal skin color.