You’ve probably noticed that sometimes when you cut yourself, blood comes out. But what is blood, and why does it come out when we cut ourselves?
Blood is made of many different parts. These parts of the blood are tiny — smaller than you can see. One part of blood is made of red blood cells which carry the air you breathe throughout your body. Red blood cells also give blood its red color.
You can see what blood cells look like under a microscope in the picture at right. (Because this picture was taken by a microscope, which makes tiny things look much larger, the cells look bigger than they do in real life.)
When you get a cut, sometimes tiny creatures that are too small to see can try to get inside your body through the cut. If some of these creatures get into your body, they can cause an infection, which makes the cut hurt a lot more. Your blood helps keep those bad creatures out. There’s another part of your blood, called white blood cells, which help keep the bad guys out of your body. Like red blood cells, white blood cells are also too tiny to see. The job of a white blood cell is to prevent bad creatures from coming into your body through a cut and infecting you.
Whenever you cut yourself, you should get help from an adult (like one of your parents or a teacher) to clean the cut and put a bandage on it.
Getting a cut is no fun, and you probably don’t like to see blood come out when you cut yourself, but remember that the blood is there for a good reason.