We’re diving deep inside the body today to take a closer look at an important organ. Is it the pancreas? The liver? Nope! Today’s Wonder of the Day is all about the spleen!

Why the spleen? Here at Wonderopolis, we say, “Why not?” Some Wonder Friends were WONDERing about the spleen and that made us WONDER, too. So now we can all WONDER about the spleen together!

The spleen is an internal body organ located in the upper left part of your abdomen (belly). The spleen sits behind and is protected by your ribs.

If you could see your spleen, it would be about the same size and shape as your fist. It’s soft and dark purple/red. Although it’s not a large organ, it can hold up to three gallons of blood! We urge you to keep your spleen right where it is, though, and simply look at pictures of spleens if you want to see what they look like.

Although you don’t hear as much about the spleen as you do other organs, such as the heart, the spleen does several important things for your body. Before you were born, your mother’s spleen worked hard to make all of your red blood cells.

Today, your spleen still works hard to maintain your supply of red blood cells. If you have red blood cells that aren’t working properly or are simply too old, your spleen will collect them and get rid of them. As it does so, it recycles the iron in the red blood cells that it gets rid of and uses them to help make new, healthy red blood cells.

The spleen is also an important part of your body’s immune system. It makes special white blood cells — called macrophages and lymphocytes — that help protect your body from infections. Your spleen also makes chemicals called antibodies that help fight infections.

The spleen is also part of your body’s lymphatic system. The lymphatic system helps keep your body’s fluid levels in balance. The spleen helps to remove excess lymph — a clear fluid that carries proteins and other important substances around the body — and returns it to the blood.

Sometimes people develop problems with their spleens. When this happens, a doctor may have to remove it during a surgery called a splenectomy. You can live without your spleen, but you may be more likely to get certain infections in the future.

In the past, many people held some weird beliefs about their spleens. Before modern medicine, many people believed their spleens were responsible for making them angry or sad. If you were in a bad mood, some people might have accused you of suffering from “vapors” caused by your spleen! Of course, we now know better thanks to science.

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    • Thanks for WONDERing with us Anish! We love to Wonder about new things and are glad you do, too! Have a WONDERful day! :)

  1. When I saw organ yesterday, I was thinking of the instrument. Not an internal organ. I didn’t know what the spleen does, or if you could survive without it. It answered a lot of questions.
    I think tomorrow’s question is about the water cycle! :)

    • Look at all the great WONDERing you’ve been up to, Emily! We think it’s SUPER that you are learning about different organs of the body– keep WONDERing with us! :)

  2. I love science, especially if they talk about the body and space. I also went to a science museum and the people who took their blood pressure had low blood pressure. But I had NORMAL blood pressure. :-D

  3. How does the spleen works? I never knew that really existed (at first). Can we still live without the ‘spleen’? Why is it called SPLEEN? Well, MOST of these questions are answered. I wonder what tommorrow’s wonder is?

    • You have been WONDERing like a champion, Sophie! We love your curiosity about the spleen and how it works together with the rest of your organs to keep you healthy! We are curious to see what else you can learn about the spleen as you continue your research and WONDERing!! :)

    • Thank you for your SUPER comment, Wonder Friend! We can’t get enough of learning new things– there is so much WONDERing to do! We hope you have a STELLAR day! Thanks for WONDERing with us today! :)

  4. I had a splenectomy after an accident back in 1960. It is now 2012 and I have lived for 52 years without it. You are right, Wonderopolis, one can live very well without this organ.

    • We are so HAPPY you shared your spleen experiences with us, Jane. We are filled-to-the-brim with happiness that you are healthy and were kind enough to share your story. We hope you have a WONDERful day– thank you for being a great Wonder Friend! :)

  5. This wonder was really interesting for me, I have been wondering about the spleen for a long time. Great wonder, wonderopolis!

    • We are so glad to know that you’ve been discovering so many Wonders today, Coco! Thanks for sharing your awesome comments with us– we can’t wait to Wonder with you again! :)

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Have you ever wondered…

  • What is a spleen?
  • Where is your spleen?
  • What does the spleen do?

Wonder Gallery

Try It Out

Ready to pretend to be a spleen? The spleen doesn’t get as much respect as many other body parts. Everyone wants to be a heart or a brain, but a spleen? There aren’t many people that want to be a spleen.

Can you write a short story from the point of view of a spleen? Tell others about what you do and why you’re important. What would the body be like without you? Maybe tell a story about a fun time you’ve had with other organs, like the kidneys or the intestines.

Use your imagination! Make your spleen story as interesting as you can. Have fun! When you’re finished, post your spleen story on Facebook to share with your Wonder Friends. We can’t wait to read about what kind of spleen you’d be!

Still Wondering

Kids are aware of many parts of the body — organs, bones, blood, etc. Through Science NetLinks’ All Systems Go! online interactive activity, kids learn about the concept of separate body systems.

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Tomorrow’s Wonder of the Day might have you singing, “Let it rain!”

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