Lymphatic system
The lymphatic system is a network of vessels, tissues, and organs that returns excess tissue fluid to the bloodstream and supports immune defense.
Lymph: Lymph is fluid carried through lymphatic vessels, containing water, proteins, cells, and other substances collected from tissues. It is the fluid the system collects and transports.
Lymphocyte: A lymphocyte is a white blood cell that includes B cells, T cells, and natural killer cells. Lymphocytes patrol lymphatic tissues and carry out many immune responses.
Lymphedema: Lymphedema is persistent tissue swelling caused by impaired lymphatic drainage. It shows the consequences of a damaged or obstructed drainage network.
Lymph node: A lymph node is a small lymphoid organ that filters lymph and provides sites for immune-cell interactions. Nodes inspect lymph as it passes through the system.
Cardiovascular system: The cardiovascular system circulates blood through the heart and blood vessels. Unlike blood circulation, lymph flow is one-way and returns tissue fluid to veins.
Lymphatic capillary: A lymphatic capillary is a tiny, blind-ended vessel that absorbs fluid and particles from surrounding tissues. These vessels collect excess tissue fluid at the network’s starting point.
B cell: A B cell is a lymphocyte that can produce antibodies and form memory cells. B cells encounter antigens and can mature into antibody-secreting cells.
Lymphoma: Lymphoma is a cancer arising from lymphocytes, often involving lymph nodes or other lymphatic tissues. It develops from immune cells housed throughout the lymphatic system.
Spleen: The spleen is an organ that filters blood, removes aged blood cells, and supports immune responses to blood-borne antigens. It is a major lymphoid organ, though it filters blood rather than lymph.
Venous system: The venous system carries blood from the body’s tissues back toward the heart. Lymphatic vessels complement venous return by collecting fluid that blood capillaries leave behind.