The thymus, lymph nodes, and spleen are all organs of which system?

The thymus, lymph nodes, and spleen are key components of the immune system. The immune system is responsible for defending the body against pathogens such as bacteria, viruses, and other foreign invaders. The thymus plays an important role in the maturation of T lymphocytes (T cells), which are critical for adaptive immunity. Lymph nodes filter lymphatic fluid and trap pathogens, allowing immune cells to recognize and respond to infections. The spleen filters blood, removes old or damaged red blood cells, and helps initiate immune responses to blood-borne pathogens. While the endocrine system regulates hormones, the cardiovascular system transports blood, and the integumentary system protects the body externally, none of these systems include the thymus, lymph nodes, and spleen as primary organs. The NEX Science exam often tests system identification by grouping organs with shared functions, making the immune system the correct choice.

======