These white blood cell-filled filters are the lymphatic system’s filtration units. They collect and destroy dangerous bacteria, viruses, and foreign particles that infiltrate the body. There are approximately 500 to 600 lymph nodes throughout the body, with clusters in the neck, underarms, chest, groin, and abdomen. The bean-shaped nodes normally range in size from a few millimeters up to 2 centimeters but may become enlarged due to the presence of a tumor. What else causes lymph nodes to swell? Discuss