We just learned about the Phagocytosis.
Another part of the immune system is the Thymus.
We learned before about the type of lymphocyte white blood cells called T cells that go to the thymus to grow.
The thymus is only a few inches long and wide, but it is very important.
When young T cells leave the bone marrow to go to the thymus they are called thymocytes.
The thymocytes get to the thymus and then they are put to the antigen test.
Antigens are things that are part of the human body, but also part of viruses.
We want our T cells to fight against virus antigens, but not human body antigents.
So this thing called the MHC tests to see if the young thymocyte is a virus fighter.
If it is a virus fighter, this is called "positive selection" and it gets to grow up to a T cell and leave the thymus.
If not, this is caled "negative selection" then it has to be destroyed or it could hurt the body.
(from: wikipedia - thymus)
Kid Facts - Blast from the past: Fovea
