The Immune System
The immune system is the body’s defense against infectious organisms and other invaders.
Through a series of steps called the immune response, the immune system attacks organisms and substances that invade body systems and cause disease.
The immune system is made up of a network of cells, tissues, and organs that work together to protect the body.
One of the important cells involved are white blood cells, also called leukocytes, which come in two basic types that combine to seek out and destroy disease-causing organisms or substances.
Leukocytes are produced or stored in many locations in the body, including the thymus, spleen, and bone marrow.
For this reason, they’re called the lymphoid organs. There are also clumps of lymphoid tissue throughout the body, primarily as lymph nodes, that house the leukocytes.
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