Lymph Nodes Stations along these vessels, called lymph nodes, trap these materials. Tonsils, for example, are lymph nodes. When you have tonsillitis you have a high temperature, you have trouble swallowing and you generally feel awful. But you feel that way because the tonsils are doing their job by trapping bacteria and preventing them from getting into your body. If they weren't doing their job, you might develop a bloodstream infection—"blood poisoning."
The lymph system begins with very small tubes that drain into lymph nodes at different levels of the body. Eventually the system feeds into the thoracic duct in the left side of the neck. That duct drains into the venous system, which returns the lymph fluid to the heart. From there it is pumped through the body.
Tumor cells can easily spread into the lymphatic system . Breast cancer, for example, often spreads initially via lymphatic vessels to the lymph nodes in the armpit (axillary nodes). If not stopped there, the cancer cells continue traveling in the lymphatics to other locations in the body. In this situation, a doctor can sometimes feel the axillary nodes during a physical examination. But just to be sure, the nodes have to be examined under a microscope after they are surgically removed.
When breast cancer spreads to the lymph glands under the armpit, we hope the glands did their job and prevented the cells from spreading any farther. You might visualize these lymph glands as train stations and the lymph blood vessels as tracks. We hope the cells behave like a local train, stopping at the next lymph node station, and don't behave like an express, scooting past several nodes and getting directly into the body.
