* Many diseases are caused by bacteria and viruses, which can live inside our bodies.

Bacteria

Bacteria are so small that they may not be seen with the naked eye. Most bacteria actually are harmless. You can find bacteria everywhere. They help maintain the balance of living creatures and chemicals. But as you may have guessed or already know, a few kind of bacteria can be harmful. Once they are in your body they can multiply rapidly and release poisons. Normally our defenders are able to attack quickly and succed, but sometimes there are so many bacteria that our bodies become ill until our cells win the battle. Also, even our defenders need help which they can get from doctors that perscribe speacial medecine for certain illnesses.

Viruses

Viruses are so small, that bacteria are bigger than them. They can not live on their own; they need your bodies cells to stay alive. They are total intruders. They not only penetrate our healthy cells but take them over and control them making them reproduce more viruses. For viruses our bodies use all their weapons. Antibodies immobilize viruses and killer cells destroy them.

* Viruses and bacteria are the most common germs that invade our bodies but other enemies also occasionally invade our bodies and challenge our defenders: yeats, fungi, worms etc............

Aids ~ VACCINATIONS ~ Organs of the Immune system ~ Lymphatic System ~ immune system ~ Cells that make up our immune system ~ Interactions in an immune response