The immune system:   Works to keep germs out of the body and destroy any that get in.

Is made up of a complex network of cells and organs that protect the body from infection, which include:

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Lymph nodes are part of the immune system.

They release lymphocytes, a certain type of white blood cell that fights infection.

The blood vessels and lymph vessels carry the lymphocytes to and from different areas in the body.

Each lymphoid organ plays a role in the production and activation of lymphocytes.

Organs in the lymph system include:

Adenoids:   Two glands at the back of the nasal passage.

Blood vessels:  The arteries, veins, and capillaries through which blood flows.

Bone marrow:   The soft, fatty tissue found inside bones where blood cells are made.

Lymph nodes:   Small organs shaped like beans, which are located all over the body and connect via the lymphatic vessels.

Lymph vessels:   A network of channels all over the body that carry lymphocytes to the lymphoid organs and bloodstream.

Peyer’s patches:   Lymphoid tissue in the small intestine.

Spleen:   A fist-sized organ in the left side of the belly.

Thymus:   A small organ behind the breastbone.

Tonsils:   Two oval masses in the back of the throat