Humans have three lines of defense against germs. The physical Barriers of our skin and mucosal surfaces provide our first line of defense. This line of defense is capable of protecting us from germs found in the atmosphere. If germs were to get in through a slit in the skin, by eating food, or any other reason, protection comes from the next two lines of defense-The Specific Response and The Inflammatory response.
The specific immune response can be separated into two parts, the Humoral (blood) Immunity and the Cell Mediated Immunity. These two connected immune functions work together. In response to germs our blood sends messages for assistance with the red blood cells, they signal that the germs should be eliminated from the body. The Cell Mediated Immune then responds with different white cells some white cells trap the germs in one place and other white cells kill them.
The Inflammatory Response is the response that can be used to fight against any type of germ; it’s a response that occurs no matter what type of germ it is. The inflammatory response clears the area infected by germs so that a cut can be repaired.
The Three Lines of Defense:
1st line of defense:
Barriers:
- Provides a nearly impassable barrier.
- Many bacteria are killed by spit. Spit also flushes germs into the stomach where the juices of the stomach kill many of the germs.
- The nose has sticky hairs that trap germs in the atmosphere.
- The ears have sticky hairs and wax to trap germs.
2nd line of defense:
Specific immune response:
1. Cell-Mediated Immunity:
- Carried out by white blood cells, which plan an immediate attack on infected areas, killing any that host germs.
- Humoral (Blood) Immunity:
- Red blood cells label areas infected by germs so that they can be killed by white blood cells.
3rd line of defense:
Inflammatory Response:
- Reacts to infection by clearing an area blocked by germs of so that a cut can be repaired.
- Some white blood cells round the germs into a corner then the other white cells kill the germs.
Basics of the Immune System:
What are Germs?
Germs are tiny little creatures, too small to see with our eyes. If they get in your body they make you sick. They make poisons that harm us. Together they become powerful armies.
Germs like warm, dark, dirty places. Sunlight and nice fresh air kills them. If we eat good food it helps our body make weapons to fight them.
Why do You Get Injections?
Some germs have secret weapons. If a lot of them attacked at once you would become very ill. So the Doctor injects some weak germs into you.
Your blood cells learn about the new special weapons from the weak germs. The blood cells work out how to destroy them after they have learnt about them. Then you are prepared for an attack.
What is a Scab?
Part of your blood makes a net when you are cut. Your blood cells bunch up behind the net. This makes a blood clot. Dried clotted blood becomes a scab.
The scab protects you while new skin is built over the cut area. When the new skin is ready, the scab falls off.
Bibliography:
World Book 99 (CD-ROM)(1998). West Monroe St. Chicago: IBM.
D.Telford, Richard & others. (1993). Take Care of Yourself. Sydney: Addison-Wesley Publisher Ltd. inc.
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URL:http://science.howstuffworks.com/immune-system2.htm
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