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Our Science Glossary glossary_l



A small molecule that binds to a specific site on a larger molecule; a protein or receptor.

Lymphatic system

The tissues and organs, including the bone marrow, spleen, thymus, and lymph nodes, that produce and store cells that fight infection and disease. The channels that carry lymph are also part of this system.

Lymph nodes

Bean-shaped structures scattered along vessels of the lymphatic system. These nodes act as filters, collecting bacteria or cancer cells that may travel through the lymphatic system.


Small white blood cells (leukocytes) that play a large role in defending the body against disease. Lymphocytes are responsible for immune responses and there are two main types: B-cells and T-cells. The B-cells make antibodies that attack bacteria and toxins while the T-cells attack body cells themselves when they have been taken over by viruses or have become cancerous. Lymphocytes secrete products (lymphokines) that modulate the functional activities of many other types of cells and are often present at sites of chronic inflammation.