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Curious About Blood?

Find out more about what's pumping through your veins

What do you know about blood — besides the fact that it’s red?

There’s more to blood than meets the eye. Melissa Larson, MD, a hematologist at Rush University Medical Center, answers some questions about blood and what can go wrong with it. 

Where do blood cells come from?

Blood cells form in bone marrow — the spongy tissue inside certain bones.

All blood cells originate from stem cells, which divide and then turn into red blood cells, white blood cells or platelets.

What is a complete blood count? And why might my doctor order one?

A complete blood count measures the types and numbers of cells in blood. A primary care doctor may order it as part of a routine checkup or if signs and symptoms suggest a problem with blood cells. These signs and symptoms can include the following:

Many people who have a blood disorder have a noncancerous condition, such as anemia — which is when the body doesn't have enough red blood cells.

What can go wrong with blood?

Many people who have a blood disorder have a noncancerous condition, such as anemia — which is the most common blood disorder. Anemia happens when the body doesn't have enough red blood cells.

Other possible problems include the blood cancers: leukemia and lymphoma.

How is leukemia different from lymphoma?

Leukemia — whether acute or chronic — is a cancer of white blood cells. It is typically found in the blood and bone marrow.

And even though it's considered a blood cancer, lymphoma tends to affect the lymphatic system — which is part of the immune system and includes your lymph nodes, bone marrow, liver and spleen.

What's the difference between chronic and acute leukemia?

There are two types of leukemia: lymphoid and myeloid. Both can be chronic or acute. Chronic leukemia is slow growing. Acute leukemia is much more aggressive.

The most common leukemia we see at Rush is chronic lymphocytic leukemia, which mainly affects older adults. This cancer grows so slowly that it often doesn’t need treatment.

Chronic myeloid leukemia is something that we do treat — with a non-chemotherapy drug that targets a specific genetic abnormality in the leukemia cell. This targeted therapy has done wonders for patients with chronic myeloid leukemia: It allows them to live with the disease as a chronic condition.

Because acute leukemia occurs quickly and is more aggressive, it needs to be treated quickly with chemotherapy and sometimes a stem cell transplant.

Did you know? Fast facts about blood

  • Our bodies produce up to 3 million red blood cells every second.
  • Blood in veins appears blue because of the way light penetrates, and is filtered by, skin. Even though blood may sometimes look blue, it's always a shade of red.
  • Bruises — which are caused by blood trapped under the surface of the skin — often start out looking red and then turn hues of purple, green, yellow and brown. This cascade of colors is triggered as the body breaks down — and reabsorbs — the trapped blood.

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