Lymph nodes and the spleen are secondary lymphoid organs that are involved in filtering and monitoring the lymphatic and blood circulatory systems for foreign substances, such as pathogens, and initiating an immune response when necessary.
Lymph nodes are small, bean-shaped structures located throughout the body along the lymphatic vessels. They contain a network of lymphatic vessels, immune cells, and lymphoid tissue that filter lymph fluid, which contains immune cells, proteins, and waste products, as it travels from the tissues to the bloodstream. The lymph nodes also act as sites for immune cell activation and proliferation in response to antigens present in the lymph fluid.
Here is an overview of the process of lymph node function:
- Lymphatic fluid flows through the lymphatic vessels and enters the lymph nodes.
- Immune cells, such as B cells, T cells, and dendritic cells, within the lymph node recognize and respond to foreign antigens present in the lymph fluid.
- Immune cells in the lymph node undergo activation and proliferation, leading to an immune response against the foreign antigens.
The spleen is a large organ located in the upper left side of the abdomen that filters blood and removes old or damaged blood cells and platelets. The spleen also plays a role in immune function by trapping and destroying foreign substances, such as bacteria and viruses, that are circulating in the blood.
Here is an overview of the process of spleen function:
- Blood flows through the spleen, where it is filtered by the spleen’s network of white pulp and red pulp.
- The white pulp contains immune cells, such as B cells and T cells, that recognize and respond to foreign antigens present in the blood.
- The red pulp contains macrophages and other immune cells that phagocytize and remove old or damaged blood cells and platelets.
Disruptions in lymph node or spleen function can lead to various immune disorders, such as lymphadenopathy or splenomegaly, which can affect immune cell activation and function.