What Does the Spleen Do

author avatar Dr. Eric Berg 08/31/2023

Have you ever heard of this little organ that is located in your abdomen? And if so, have you ever wondered what it does? In this article, I will answer the question, "What does the spleen do?" and help you better understand this infection fighting, recycling plant of the body.

I will cover:

Let's start by looking at what exactly the spleen is and where it is located in the body.


What is the spleen?

Blue illustration of female body and internal organs, with spleen anatomy in red.

The spleen is one of the internal organs located in your abdominal cavity. It is found in the upper left of the abdomen, to the left of the stomach and under the diaphragm.

It can vary in size and is usually between 2.8 to 5.5 inches long (about fist-sized). It can get bigger when you have an enlarged spleen, which can happen when you get sick, for example. It is oblong and purple.

If you were to look at the spleen anatomy, you would see that it has a lot of vessels in it. These carry fluids to and from other parts of your body.

Although the human spleen is a small organ, it actually keeps quite busy and does a lot to keep your body healthy.

It is considered one of the immune system organs and is part of the lymphatic system as well. It works alongside other parts of the body, such as the lymph nodes and bone marrow, to do its job.


What does the spleen do? 4 major functions

The spleen serves 4 main functions in the body. These functions include:

1. Recycling blood cells

The primary function of this organ is to act as a recycling plant for old blood cells.

All red blood cells pass through the spleen, where they basically go through a screening process.

Healthy red blood cells go through, while unhealthy, damaged ones don't. The damaged ones get broken down by large white blood cells called macrophages. It is important to get rid of the old red blood cells so that they don't damage blood vessels. For this reason, they are monitored closely.

But the spleen doesn't just get rid of old blood cells. Instead, it saves any usable parts of the red blood cells, like iron, to be reused and recycled.

Think of a junkyard. People bring in their damaged, junky cars to the yard. But the car isn't thrown directly into a trash heap – any usable parts are salvaged first. Metals and other things that can be saved are put through a recycling process and are eventually used to make new things.

That is essentially what the spleen does. It recycles deformed, old red blood cells and converts them into usable things. For example, it can convert some of the materials into brand new amino acids to be used in the body. It also saves iron. And it can also recycle platelets and white blood cells.

2. Acting as a blood reserve

The organ also stores blood. It can hold about a cup of blood as a reserve. Should you have a trauma of any sort and need extra blood, it will release the store back into the blood stream.

It is sort of like an emergency backup for when you might be low on blood and need some extra.

Illustration of red blood cells floating around in blood on red background.

3. Enhancing immune system

The spleen is involved in part of the immune response.

In a similar way to which the spleen can pick out bad blood cells from the rest, it can also sort out unwelcome, harmful, foreign invaders from the crowd. Cells called lymphocytes have the job of destroying those invaders.

People without spleens (who have had them removed through a splenectomy) are at a higher risk of infection. Because they don't have this immune system booster, they can't fight things off as easily as other people.

The spleen is like a first line of defense for the immune system.

4. Killing bacteria

As mentioned above, the spleen sorts out foreign invaders like bacteria, and then it kills them. It produced lymphocytes in response, and these lymphocytes jump into action and kill the bacteria.

This makes the spleen an infection-fighting organ that plays an important role in killing unwanted bacteria and keep us healthy.

When things go wrong

There are many things that can happen that harm the spleen. When things go wrong, you get an enlarged spleen.

An enlarged spleen can be caused by many things such as:

If you have an enlarged spleen over time, it can impair the ability of the spleen to operate normally. And it can even cause pain or other symptoms.

The spleen is not considered a vital organ. That means that you can live without it, and many people do.

Some people have had their spleens surgically removed through a procedure called a splenectomy. This may happen because it has become enlarged (due to some of the reasons listed above), or because of a physical injury to the area.

Fortunately, if you've had a spleen removal, other organs like the liver can take over and perform many of the same functions.

However, if you have had a splenectomy, you are at higher risk of getting infections. Your susceptibility to getting sick is increased, so you'll have to be more careful and take certain precautions to stay safe.


Key takeaways

The spleen is a small organ, but it carries out many important functions and stays busy keeping the body healthy.

Here are the main points to remember:

  • Its main function is to recycle worn-out blood cells and take what can be used before destroying the rest. It recycles red blood cells, iron, platelets, and white blood cells.
  • It also stores reserve blood for emergencies.
  • It also has an immune component, helping to kill bacteria and fight off infections.
  • An enlarged spleen can be caused by many factors, including infections, liver diseases, and more.

Have any questions or comments relating to this small but important organ? Go ahead and leave me a comment below with your thoughts.

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