Thymus

Definition

The thymus is a primary lymphoid organ located in the upper chest, responsible for the maturation and differentiation of T lymphocytes. It plays a crucial role in the development of adaptive immunity.

5 Must Know Facts For Your Next Test

1. The thymus is largest and most active during childhood and gradually shrinks after puberty.
2. T cells mature through a process involving positive and negative selection within the thymus.
3. Thymic epithelial cells present self-antigens to developing T cells to ensure self-tolerance.
4. A failure in thymic function can lead to immunodeficiency disorders or increased susceptibility to infections.
5. Autoimmune diseases can result from improper negative selection of autoreactive T cells within the thymus.

Review Questions

• What are the main functions of the thymus?
• How does the thymus contribute to self-tolerance?
• What happens to the size and activity of the thymus after puberty?

Related terms

T Lymphocyte (T Cell): A type of white blood cell that plays a central role in cell-mediated immunity.

Positive Selection: The process by which developing T cells that can recognize self-MHC molecules are selected for survival.

Negative Selection:

The elimination of T cells that strongly bind to self-antigens, preventing autoimmunity.