Lymph nodes are part of the lymphatic system, which 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 system
against disease. The lymph nodes (sometimes called lymph glands)
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. Lymph nodes may
be found singly or in groups; they may be as small as the head
of a pin or as large as an olive. Groups of lymph nodes can be
felt in the neck, groin, and underarms. Many lymph nodes in the
body can't be felt. 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, the lymph nodes in the neck may swell and become
tender. Cancer can spread through the lymphatic system.
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