Final answer:
Lymph nodes are small bean-shaped structures that filter harmful substances and help fight infection by removing debris and pathogens from the lymph, as well as facilitating adaptive immune responses.
Step-by-step explanation:
Lymph nodes are small bean-shaped structures that filter substances and fight infection in the body. These nodes function to remove debris and pathogens from the lymph, earning them the designation of "filters of the lymph". Bacteria and other pathogens that infect the interstitial fluid are captured by the lymphatic capillaries and transported to a regional lymph node where dendritic cells and macrophages internalize and destroy many of the invaders.
Lymph nodes facilitate the adaptive immune responses mediated by T cells, B cells, and accessory cells of the immune system. They provide both the structure and support necessary for efficient immune functionality. Lymph nodes are crucial for maintaining an environment free of microorganisms in the blood and the lymphatic system, highlighting their importance in overall health and immune defense.