Thymus Disorders

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  • 0:02 The Thymus
  • 0:25 Thymosin
  • 1:35 Thymitis, MG, & Thymectomy
  • 2:44 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

There's a cool organ in your body that does a sort of disappearing/reappearing act, depending on circumstances. It's called the thymus. You'll learn when it does this and some important terms related to it.

The Thymus

Hey, did you know you're born with an organ that eventually shrinks as you age? Did you know that it can also be enlarged later in life in some people, abnormally so? There's a confusing organ if there ever was one!

This structure is called the thymus, a lymphoid organ that's important for normal immunological development in people. This lesson will tell you a bit more about it.


The thymus has a really important role. It's the center for the maturation of certain lymphocytes, a type of white blood cell, called T-lymphocytes. The hormone responsible for the maturation of T-lymphocytes, one that is secreted by the thymus, is called thymosin. The T-cells are super important for the protection of your body against foreign invaders. They can either directly kill the foreign invaders or activate other cells, called B lymphocytes, that help fight off the infection instead.

This is why someone who is born with an underdeveloped or absent thymus, as per DiGeorge Syndrome, will have problems fighting off infections. This is because an absent or undeveloped thymus is akin to a city's police force having no police academy. If there's no police academy, new recruits can't be trained to mature into fine and outstanding police officers that protect the city from crime. In our body, the thymus is the police academy for the T-cells, it trains them to defend our body from criminals, like bacteria and viruses, out to destroy us! And so you can see why its presence is really important!

Thymitis, MG, & Thymectomy

While people with DiGeorge syndrome are born with an underdeveloped thymus, there is a condition that can cause the thymus to be an abnormally large size during adulthood. Remember, in adulthood the thymus is supposed to be a smaller remnant of what it once was when you were a child. This condition is called myasthenia gravis (MG), an autoimmune disease that results in muscle weakness.

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