The defense system of our body is a complex network of organs containing cells that recognize infections and diseases in the body and destroy them. When functioning properly, the immune system can distinguish between healthy tissues and critical viruses and bacteria. This system contains the thymus, white blood cells, antibodies, epidermis, cilia, mucus, and saliva. The thymus is a small organ where white blood cells mature. White blood cells are divided into two groups. One creates antibodies that attack bacteria and the other that helps destroy infected or cancerous cells. An example of how our cells and tissues work together is when skin layers such as the epidermis protect our body from disease-causing viruses. Finally, cilia, mucus, and saliva trap dust and other bacteria that may enter your nasal passages or mouth. To remove the bacteria, they sneeze or cough. Together, all of these parts of the immune system work together to create immune responses. There are three types of defense line. The line of defense is the ability to defend and protect the body from i...