Fighting Infection

Our bodies come in contact with all sorts of things every minute. Our skin contacts the world around us, occasionally getting damaged along the way. Our digestive system has to deal with whatever materials we ingest. Our eyes and nose provide inroads for infection as well.

You see, infection is when any foreign material comes in contact with our body tissues. By foreign, I mean anything that isn't supposed to be in our bodies... it isn't natural for our bodies. Generally, we are concerned about infection by harmful bacteria, viruses, harmful fungus, and other parasites. An entire course on these infectious agents is available, and it is called "microbiology." Therefore, I will not go into much detail on them here. I just want you to know that bacteria are everywhere-- no matter how many products try to convince you that they make your world bacteria-free, they do not. But that's OK, because not all bacteria are harmful (some are really helpful), and our bodies are designed to prevent anything harmful from entering.

In this section of Unit 21, you will be learning how our bodies are designed to block entry of foreign material, as well as how our bodies handle the situation when foreign material finds a way through our blockades and enters our bodies.