Immunity is that that mechanism by which your body is protected from invasion of external bodies, through its own physiological or artificial means. The immune system is the collection of organs and tissues involved in the adaptive defense of a body against foreign biological material.

It may be broken down into the adaptive immune system, composed of four lymphoid organs (thymus, lymph nodes, and spleen and sub mucosal lymphoid nodules) and the group motile cells that are involved in the body's defense against foreign bodies. The term may also be used to refer to the totality of a body's defense systems, encompassing both the adaptive immune system.

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