The Human Immune System

The Immune System
The immune system are processes and structures within an organism to help protect it from foreign attackers. The immune system consists of cells, tissues, and organs; such as lymphocytes, lymph nodes, phagocytes, and many others.
In order for the immune system to function properly it must first learn to discriminate between self-cells and foreign cells. Cells marked “self” need to be left alone. Cells that are foreign should be identified as “non-self” and cause the immune system to start to defend the body. Any foreign microbe or antigen, an antigen is any substance that causes an immune response, will activate the immune system. To prevent an auto immune disease, a disease where the body attacks its own cells, cells must first undergo central tolerance; the immune system’s ability to recognize self-cells and not attack them. There are two types: first, central tolerance, and second, peripheral tolerance. Central tolerance is acquired when the cell is first developing in bone marrow; the immature immune cell must learn to not attack its own bodily cells. If the ...