Your skin is a barrier from harmful things in the environment. When skin becomes damaged blood quickly clots ( thanks to platelets in the blood ) around the damaged area to form a dry crust, called a scab. This protects your body from any nasties which could take advantage of the new opening in your skin.

It might feel quite satisfying to pick a scab, but underneath there’s a lot going on and the scab is definitely best left in place. There’s dead bacteria, live bacteria, phagocytes ( white blood cells ) and maybe even pus. Pus is yellow gooey stuff which is mostly white blood cells, dead bacteria and skin cells! Macrophages ( a type of white blood cell ) under the scab eat and destroy bacteria. These can call out for extra help from B cells, which produce antibodies to flight infection.

The basic function of a scab is to protect the damaged area while new skin cells are made and any damaged vessels repaired.

Immune response after injury - what is a scab

If you do manage not to pick them, scabs eventually fall off, revealing the new skin underneath.

Scabs usually start as a red colour which becomes darker as the scab dries and thickens. They often become lighter as the skin heals.

Yellow in a scab is a sign of pus, which is usually a sign of infection and should be investigated by a doctor!

Remember to keep an area of damaged skin, clean and dry.

Try our fake blood recipe to watch pretend blood thicken like a blood clot, then make a jelly scab!

jelly scab

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Originally posted at Science Sparks