Thymus facts for kids

The thymus is a very important organ that is part of your immune system. Think of your immune system as your body's personal army, always ready to fight off invaders like germs and viruses. The thymus is located right in front of your heart and behind your sternum (that's your breastbone).

Inside the thymus, special cells called T cells (or T lymphocytes) grow up and learn their jobs. These T cells are super important for your adaptive immune system. This is the part of your immune system that learns to recognize and fight specific germs it has seen before, making you immune to them.

What is the Thymus?

The thymus is a special kind of lymphoid organ. This means it's part of the network in your body that helps keep you healthy by fighting infections. It's a bit like a training camp for your immune cells.

Where is the Thymus Located?

Your thymus is found in your chest, tucked away safely. It sits just above your heart and behind your sternum. It's a small but mighty organ that plays a big role in your health, especially when you are young.

What Does the Thymus Do?

The main job of the thymus is to help T cells develop. These T cells start as basic blood-forming cells (called hematopoietic cells) and travel to the thymus. Once there, they go through a special training program.

T Cell Training Camp

During their time in the thymus, T cells learn two very important things:

• They learn to recognize and attack harmful invaders like bacteria and viruses.
• They learn to ignore and not attack your own body's healthy cells. This is called "self-tolerance," and it's crucial so your immune system doesn't accidentally harm you.

The Thymus Through the Years

The thymus is biggest and most active when you are a baby and during your pre-adolescent years (around 12-15 years old). This is a time when your body is growing rapidly and needs a strong immune system. As you get into your early teens, the thymus starts to slow down a bit. However, it still continues to make new lymphocytes (which include T cells) throughout your adult life, helping to keep your immune system strong.

Images for kids

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  A close-up view showing a small section of the thymus. The darker purple area is the cortex, and the lighter area in the middle is the medulla.

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  A magnified view of a Hassall's corpuscle, which is a structure found inside the thymus.

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  On an chest X-ray, the thymus looks like a bright area near the top of a child's right lung.

See also

In Spanish: Timo para niños