As we all know, leukemia is the form of cancer that affects the bone marrow of people. The bone marrow is the spongy substance that we all have on the insides of our bones, this being responsible for the production of the white and red cells and of course the platelets. When leukemia appears in people the white blood cells start dividing in an abnormal way and out of control. Their numbers get very high and thus start crowding the other normal cells in the blood. Being the fact that they are not yet mature, the white cells that are so many now in the blood stream, can not perform the proper functions that the other normal healthy cells would have. Problems start poring down now on the patient. Organs stop receiving the right amount of nutrients and oxygen, the body becomes in danger of suffering because of the attacks of the diseases and viruses and of course blood doesn't clot as it should have done when a cut occurs and the blood enters into contact with the air.

In children, the most common type of leukemia found is acute lymphocytic leukemia. Less common in the cases of children is the appearance of acute myeloid leukemia. Some 5 % of childhood leukemia form a distinct chronic type of the disorder. If the children under 2 develop the disease than it is clear that they have juvenile myelomonocytic leukemia. In general children suffer only from acute types of leukemia, the chronic ones affecting grown ups mostly after the age of 40.

We all know that the bone marrow is the one responsible of producing the red, white and platelets cells. But few of us know that in fact the bone marrow produces stem cells that later one, depending on the message received from the brain, develop into the normal cells that we have in our blood. Also we see a minor division in the type of white blood cells. This way we see that there are granulocytes, monocytes, B-lymphocytes and T- lymphocytes. The granulocytes white cells fight bacteria by actually surrounding them and eating them; the case is monocytes is that they fight germs, but it's not the case as in granulocytes. The B-lymphocytes attach antibodies on germs and by this they trigger a mass response from other WBC that also attach antibodies to the germs, this way distroying them. The T-lymphocytes act more like a little look out cells telling the WBC when they have found an intruder or a germ and directing them to fight it.

Because the large number of white blood cells crowd out the other cells, the normal functions of the body stop working normally leading to certain signs like anemia and of course fatigue. The bruising also appears more easily in children patients of leukemia, not to mention the fact that if a cut occurs a lot of bleeding is done till the blood actually clots. Infection is a serious problem for patients with any kind of leukemia.