Khan Academy on a Stick

Hematologic system diseases

Blood is incredibly important in combating disease and the healing process after an injury. It acts as a highway for medicine, stops bleeding, fights infections, controls cells from multiplying too fast, and so much more. But things can go wrong with blood too! What if your blood couldn’t clot and stop you from bleeding, or started to clot uncontrollably? What if your red blood cells or white blood cells suddenly disappeared? Blood contains many different types of tissues doing very different jobs, making diseases of the blood produce a variety of symptoms, including continuously feeling tired and bone pain. Learn about the different blood diseases, how they are diagnosed, and the cool ways health professionals treat these conditions.

Health and medicine

Anemia

Hematopoiesis
Hematopoiesis is the process of creating new blood cells in the body. All blood cells start off as hematopoietic stem cells, and then specialize (differentiate) into myeloid cells (erythrocytes, megakaryocytes, monocytes, neutrophils, basophils, or eosinophils) or lymphoid cells (T-lymphocytes and B-lymphocytes).
What is leukemia?
Leukemia is a collection of cancers which create a large amount of immature blood cells. These immature blood cells take up space in the bone marrow, preventing the bone marrow from making healthy blood cells such as platelets, red blood cells, and white blood cells. Learn about the symptoms of this disease which include prolonged bleeding, frequent infections, and bone pain.
Leukemia pathophysiology
Sometimes an immature blast cell have two gene mutations which prevent it from maturing into a specialized blood cell and cause it to multiply out of control. These immature blast cells crowd the bone marrow and impair the ability of the bones to make healthy blood cells. This leads to a decrease in platelets, red blood cells (RBCs) and white blood cells (WBCs).
Leukemia diagnosis
Often health care professionals conduct a variety of blood tests to determine if someone has leukemia. Leukemia patients often have decreased levels of platelets, white blood cells (WBCs), red blood cells (RBCs), hematocrit, and hemoglobin. Other tests such as bone marrow aspirations can reveal an increase in immature blast cells. Learn how health professionals classify leukemia by staining sample tissue with a dye and by looking for chromosome translocation.
Leukemia classifications
Learn how leukemia can be classified as an acute or chronic and myeloid or lymphoid disease.
Acute leukemia
Acute leukemias affect specialized blood cells at the most immature stage in their growth. Acute lymphoblastic leukemias (ALL) are the most common cancer in children and is often associated with people who have down syndrome. Learn about B-cell ALL and T-cell ALL, as well as the different acute myeloid leukemias.
Chronic leukemia
Chronic leukemias affect specialized blood cells that are partially through the process of maturation. Chronic lymphoblastic leukemias (CLL) often cause an enlargement of the liver and spleen. Involvement of the lymph nodes in CLL is often called small lymphocytic lymphoma. Learn how small lymphocytic lymphoma can transition to diffuse B cell lymphoma.
Myelodysplastic syndrome
Myelodysplastic syndrome is sometimes referred to as “pre-leukemia” or a condition that occurs before leukemia (although most patients will never develop leukemia). In myelodysplastic syndrome, the gene mutation preventing the maturation of the blast cell is present, however the second gene mutation leading to uncontrolled cell replication is absent. Learn how health professionals look at blood test results and bone marrow aspirates to diagnosis this disease.
Leukemia treatment
There are three main solutions to treat leukemia. Chemotherapy is a collection of drugs which target cells that rapidly multiply (a key characteristic in cancer). Radiation is often used on patients who are at a high risk of the leukemia entering the brain. For resistant leukemias, bone marrow transplantation is considered.

Khan Academy on a Stick

Hematologic system diseases

Anemia

Leukemia

Iron deficiency anemia and anemia of chronic disease

Plasma cell dyscrasias