The lymphatic system is made up of a network of lymph nodes and
vessels or channels throughout the body. This system carries lymph fluid,
nutrients, and waste material between the body tissues and the
bloodstream.
The lymphatic system is also an important part of the immune
system, the body's defense against disease. The lymph nodes filter lymph fluid
as it flows through them, trapping bacteria, viruses, and other foreign
substances, which are then destroyed by special white blood cells called
lymphocytes.
When a part of the body is infected, the nearby lymph nodes become
swollen as they collect and destroy the infecting organisms. For example, if a
person has a throat infection, lymph nodes in the neck may swell and become
tender.
Cancer can spread through the lymphatic system.