What are white blood cells and how do they relate to the lymphatic system?

White blood cells, or leukocytes, are crucial components of the immune system that help the body defend against infections and foreign invaders. They are produced in the bone marrow and circulate through the bloodstream and lymphatic system. The lymphatic system plays a key role in immune response by transporting white blood cells to lymph nodes, where they can encounter pathogens and initiate an immune response. Thus, white blood cells and the lymphatic system work together to maintain the body's defense mechanisms.