The lymphatic system is integral to the immune response and is responsible for housing white blood cells, particularly lymphocytes, which play a crucial role in defending the body against infections and diseases. This system includes lymph nodes, lymph vessels, and other lymphatic organs such as the spleen and thymus.
White blood cells travel through the lymphatic system and are activated in response to pathogens. Lymph nodes filter lymph fluid and are key sites where immune responses can be triggered. The lymphatic system also works alongside the cardiovascular system to circulate these immune cells throughout the body, but its main function is specific to immunity.
Other systems such as the nervous system, cardiovascular system, and digestive system have distinct roles that do not focus primarily on the storage and function of white blood cells for immune defense. The nervous system is primarily responsible for controlling and coordinating bodily functions through signals. The cardiovascular system is mainly involved in transporting blood, nutrients, and waste products throughout the body, while the digestive system is focused on the breakdown and absorption of food. Thus, the lymphatic system stands out as the primary system associated with immunity and the housing of white blood cells.