To prevent and get rid of the germs of the body.
Typically, the body of the people, we have a mechanism to prevent and get rid of the germs live naturally, compared with Dan walls or forts that have been created for the interception or intercept throws obstacles destroy germs in order to prevent harm to cells, tissues or organs that are important within the body to act until a fatal disease. Dan or organs that help prevent and get rid of the germs that have all the automatic checkpoint 3 together: