The lymphoid organ that functions primarily during youth and then begins to atrophy is:
a. Spleen
b. Thymus
c. Palatine tonsils
d. Bone marrow

Verified step by step guidance

1. Understand the function and lifespan of each lymphoid organ listed: the spleen, thymus, palatine tonsils, and bone marrow.
2. Recall that the thymus is most active during childhood and adolescence, playing a crucial role in the development of T lymphocytes (T cells) for the immune system.
3. Recognize that after puberty, the thymus begins to shrink or atrophy, a process called involution, which reduces its size and functional tissue.
4. Contrast this with the spleen, palatine tonsils, and bone marrow, which do not primarily atrophy after youth but continue to function throughout life.
5. Conclude that the lymphoid organ that functions primarily during youth and then begins to atrophy is the thymus.

Key Concepts

Thymus Function and Development

The thymus is a primary lymphoid organ responsible for the maturation of T lymphocytes during early life. It is most active during childhood and adolescence, after which it gradually shrinks or atrophies, reducing its functional capacity in adulthood.

Lymphoid Organs and Their Roles

Lymphoid organs include primary organs like the thymus and bone marrow, where lymphocytes develop, and secondary organs like the spleen and tonsils, which filter lymph and blood and facilitate immune responses. Each organ has distinct functions and activity timelines.

Atrophy in Lymphoid Organs

Atrophy refers to the reduction in size and function of an organ over time. In the immune system, the thymus undergoes physiological atrophy after puberty, unlike other lymphoid organs such as the spleen or tonsils, which remain active throughout life.