Activity: Fake wounds

Create a fake wound while learning how the body repairs itself.

You will need

• Petroleum jelly
• Toothpick
• Plastic spoon
• Bowl
• Red food colouring
• A white tissue
• Powered cocoa

What to do

1. Place a spoonful of petroleum jelly in to the bowl
2. Add three or four drops of red food colouring and mix with the toothpick
3. Stir in a pinch of cocoa powder to make the colour a dark blood-like red
4. Separate the tissue so you only have one layer
5. Rip out a small rectangle, the size you would like your wound to be
6. Place the tissue on your body where you want the wound to be
7. Using the spoon or your finger cover the tissue with clear petroleum jelly
8. Now mould the goopy tissue to form a wound, the sides of the wound should be higher than the centre
9. Smear the blood-colour petroleum jelly in the centre of the wound
10. Sprinkle cocoa onto the edges and rub the cocoa in to the make the edges dark
11. You may want to add some cocoa to the centre as well
12. Go show someone

What's happening?

As soon as you break your skin by cutting or scraping yourself, your body starts work to repair the damage. The body has many jobs to do to repair the damage: stop the bleeding, put its own "bandage" on, get rid of any germs and fix the torn skin.

A scab is like nature's band-aid and 10 seconds after you have cut your skin, your body is working to repair itself. First of all, the alarm is sounded and chemical proteins react with special blood cells called platelets, which cause the blood to get sticky and clump together (which looks like the petroleum jelly and red food colouring mixed together). The platelets form a blood clot, which acts to stop the bleeding. Once your body has stopped the blood leaving your body, it starts working to dry out the clot and form a scab to protect the wound from germs. While all this is happening, the cells underneath the scab start working on making new skin.

Just in case any bacteria, which love to feast on blood, make it to the wound before the scab is formed, the body sends white blood cells to eat any germs that make it past the scab. This stops your cut from becoming infected (the white blood cells look like the clear petroleum jelly used in our activity).

Usually there is some yellow icky stuff. This is called pus and is the result of piles of living and dead germs and cells, the aftermath of the battle to fix your cut. If you can resist picking your scab and leave your body to fix itself, it will send a new kind of cell called a macrophage. These cells will eat all the pus, any dead white cells and anything left behind. Within a week or two, when the new skin is formed, the scab will fall off by itself. If you pick at a scab, you may damage the new skin that is growing underneath which could cause a scar. So try not to pick at scabs.

Applications

Your body has built-in military teams to attack and repair the damage when you've cut yourself and, if it's a small wound, your body should have no problem fixing itself. Sometimes, if the wound is big or there's dirt in it, you may need to help the repair work along by cleaning the area, stopping the bleeding or protecting the wounded area.

It's a good idea to let someone know if you are injured. Especially if you cut yourself on something dirty, rusty, or if you get bitten or scratched (by an animal or a person!) as you might need a tetanus shot.

Sometimes, a cut, scratch, or abrasion starts out as no big deal, but then gets infected. An infection happens when there are too many germs for your body's white blood cells to handle. Infected wounds may hurt, look red and swollen and contain pus, a yellowish or greenish thick liquid. If your cut, scratch, or abrasion looks infected, you should let someone know.

But more often, your cuts, scratches, and abrasions go away on their own, thanks to your body's amazing ability to heal itself.