Final answer:
Lymph nodes are the filters within the lymphatic system that remove pathogens from the lymph before it merges back into the bloodstream.
Step-by-step explanation:
The lymphatic system plays a crucial role in maintaining the body's fluid balance and defending against pathogens. Within this system, lymph nodes act as the lymphatic filter within the blood vascular tree by capturing, filtering, and destroying pathogens such as bacteria and viruses from the lymph before it returns to the bloodstream. The structure of lymph nodes facilitates this process with a maze of connective tissue and various immune cells like lymphocytes, dendritic cells, and macrophages which work together to clean the lymph.