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Immunity - How the body defends itself

The Body's Immune System:

The Immune system is a set of biological processes which work to prevent illness and disease by attacking foreign elements within. The human body is exposed to billions of foreign bodies or antigens each and every day. If an antigen enters the body, the immune system goes to work to destroy it.

How does the Immune System Work?

This is done mainly by the B-cells and killer T-cells in the human body. B-cells make their own germ fighting weapons called antibodies that protrude from the B-cells like tiny Y-shaped antennae. When a B-cell comes into contact with an antigen for which it has an antibody, it locks onto it and begins dividing. Soon, millions of new B-cells have been created. When enough B-cells have been made, they stop dividing. They become plasma cells, a type of cell that makes free antibodies. These free antibodies do not stay attached to the B-cells, but roam around freely, looking for invading antigens that they can bind onto. After an antibody attaches itself onto a target antigen, the antibody changes into a shape that is easier for a macrophage to latch onto. By releasing antibodies, therefore B-cells help macrophages devour and kill invading organisms. Some B-cells continue dividing for a long time, sometimes for years. If a germ tries to invade the body again, these B-cells called memory cells remember it and are ready with the needed antibodies. This is how the body becomes immune to a disease it has had in the past.

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