Immune system

The immune system is the system of specialised cells and organs that protect an organism from outside biological influences. In a broad sense, almost every organ has a protective function (e.g., the skin). When the immune system is functioning properly, it protects the body against bacteria and viral infections, destroying cancer cells and foreign substances. If the immune system weakens, its ability to defend the body also weakens, allowing pathogens, including viruses that cause common colds and flu, to grow and flourish in the body. The immune system also performs surveillance of tumor cells, and immune suppression has been reported to increase the risk of certain types of cancer.

Related Topics:
System - Cell - Organ - Organism - Biological - Skin - Thymus - Bacteria - Viral - Infection - Cancer cell - Pathogen - Common cold - Flu - Cancer

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The immune system is often divided into two sections:

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• innate immunity: encompasses unchanging mechanisms that are continuously in force to ward off noxious influences;
• adaptive immunity: responds to new influences by mounting an immune response.
 
Immune system: Types of immune system ►