What is the primary purpose of the lymphatic system?

The primary purpose of the lymphatic system is to defend the body against pathogens. This system plays a crucial role in the immune response by transporting lymph, a fluid containing immune cells, throughout the body. Lymphatic vessels collect excess interstitial fluid from tissues, which is then filtered through lymph nodes. These lymph nodes contain a high concentration of lymphocytes—white blood cells that help identify and combat infectious agents. When pathogens such as bacteria or viruses enter the body, the lymphatic system helps detect and respond to these threats, contributing to the overall immune defense mechanism.

Additionally, while other systems listed have their own important functions, they do not encompass the primary role of the lymphatic system in immune defense. The circulatory system transports blood and nutrients; the respiratory system is involved in gas exchange; and temperature regulation is primarily managed by the integumentary system and circulatory mechanisms. Therefore, the lymphatic system is distinct in its essential function of defending the body against infections and maintaining fluid balance.