You're spinning and spinning and spinning. The ice feels smooth under your skates. Your ankles feel stong. "I could be in the Ice Capades," you think.

But then something goes wrong. You lose your balance and come down -- THUMP -- on the hard ice, right on your knees.

OUCH!

Minor accidents like this one can cause painful cuts, scrapes and bruises. Luckily, the injuries aren't very serious. They hurt for a while, but they heal quickly.

Here's what happened when you got that bruise on your knee. When you landed on the ice, you hit hard. The smooth ice didn't break your skin, so you didn't get a cut. But you did hit hard enough to break tiny blood vessels under the skin.

When the vessels break, the blood inside them leaks out into your tissues. It has nowhere to go. The broken vessel quickly heals itself up. But the blood that leaked out stays in your tissues for a while.

At first, the banged-up place on your knee looks red. But it soon begins to turn into a black-and-blue mark. That happens as special parts of your blood called platelets stick together, forming a sticky web. This begins a process called clotting. As your blood clots, it turns a darker color. The mark on your leg begins to look black and blue. The tissues around the clot may swell up, too.

What you see when you look at the black-and-blue mark on you knee is the clotted blood under your skin, showing through the way a drawing shows through tracing paper. If you have light skin, the bruise is easy to see. If your skin is dark, the bruise may not be as visible.

But it's still there -- and it still hurts. That's because swelling around the clotted blood puts pressure on your nerves, causing pain.

Over the next few days, your nasty-looking bruise will fade. This happens because special parts of your blood go to work to clean up the spill.

Your blood is a mixture of different parts. You've already learned about the platelets. It also has: Red cells, which carry oxygen; White cells, which fight germs; Plasma, the liquid part of the blood, which contains many different useful chemicals.

White cells are part of a clean-up crew on the spilled blood that forms your bruise. They gobble it up. As the white cells absorb the spilled blood, the black-and-blue mark gradually disappears.

Now let's look at the other knee. When you fell, it hit a rough place on the ice. There's blood on your tights, and your knee is throbbing with pain. You've got a cut.

You feel pain because tiny nerves in your skin send a message to your brain. The message says, "Something is wrong. Send help!" Many nerves are just under your skin, which can make a bump, a bruise or a cut pretty painful. But those nerve endings help you, too. They warn you to pull your finger away from the sharp point of a knife. They make you snatch your hand away from a hot stove. And they let you know when it's time to start taking care of your cut.

If the cut on your knee looks deep, and if it is bleeding a lot, show it to an adult. You may need to see a doctor to have the injury stitched shut. But if the cut is a small one, and if it doesn't hurt very much, you can use simple first aid methods to treat it.

Wash your cut off with warm water and soap. Then cover it with a clean gauze pad, and push down gently. The pressure helps stop the bleeding. Then put on a bandage to cover the cut. The bandage keeps germs from invading the cut and causing an infection. If your cuts and bruises are aching, you might put ice on them to dull the pain.

Once your cut is nicely covered, you can forget all about it, and let your body heal it up.

As soon as you got the cut on your knee, your body started to heal it. The blood flowing out of the cut carries away any germs that may have gotten in. White blood cells arrive to fight any germs that might stay behind.

In the meantime, the blood in the cut starts to clot, or hold together. Platelets in your blood plug the broken blood vessels. Then special fibers in the clot shrink, pulling the sides of the cut together. Now you've got a scab.

Under your scab, new skin cells begin to grow. Your blood carries in chemicals to help build the new skin. Once new skin has replaced the broken skin, your scab falls off. You're as good as new.

After about a week, your cut is nicely healed. Time to go skating again . . . and be careful this time! Tips for Parents

Teach your child these simple first aid methods for treating minor cuts. For extremely deep or wide cuts, consult your doctor:

* Wash the cut with soap and water.

* Stop bleeding by applying gentle pressure with a clean cloth or gauze pad.

* Cover the cut with an adhesive bandage or gauze and tape, making sure the protection isn't too tight.