How does a graze heal?

After the game, Na dashed indoors, tripped on the step and grazed her knee. Mum rinsed the graze with clean water and put a plaster on it. Two days later, a hard, dark brown scab had formed, crisp as a rice cracker.

Cú Bông guessed the scab was dried dirt on the cut and ought to be picked off.

Na picked one corner by accident: it bled a little, and days later a new scab formed. The part she left alone came off by itself after more than a week. Underneath was new skin, pink and whole.

When skin is grazed, tiny bits in the blood called platelets stick together. With thin threads called fibrin, they make a clot, and the bleeding stops. The clot dries and hardens into a scab.

The scab keeps germs out while the skin underneath heals. Under it, new skin grows; once healed, the scab falls off by itself, usually after a week or two. Picking a scab can open the wound again, so it heals more slowly and may leave a scar.

Step through to watch a graze heal. At which step does the bleeding stop?

When skin is grazed, the blood clots and dries into a scab that keeps germs out. New skin grows underneath, so leave the scab alone and let it fall off.