Definition

The child's immune system is an intricate network of interdependent cell types, substances, and organs that collectively protect the body from bacterial, parasitic, fungal, viral infections, and tumor cells.

Description

The immune system was not recognized as a functional unit of the body until the late twentieth century, probably because its parts are not directly connected to each other and are spread in different parts of the body.

Organs of the immune system

The immune system contains the following organs and cells: tonsils and adenoids; the thymus gland; lymph nodes; bone marrow; and white blood cells that leave blood vessels and migrate through tissues and lymphatic circulation. The spleen,...