Lewis/Life - Teaching Techniques

Chapter 39 - Teaching Techniques

A. General Tips
** See the General Tips notes in Chapter 30 of this Instructor's Manual.
Correlate this information on AIDS with the information on pages 253-255. Formulate a positive approach you feel could be taken to deal with the AIDS problem. You might wish to refer back to your previous AIDS discussion. Be certain you have the latest information available.
You might wish to copy and distribute to your students the Overview of Chapter Objectives flowchart found at the beginning of this Instructor's Manual Chapter.
B. Possible Approaches to the Chapter
You will probably find your students have a very fuzzy idea about what the immune system really is. I suggest you begin this chapter with a non-quiz. For instance, ask the students to define the immune system or to write down all the body defense mechanisms they can think of. Many of them will mention white blood cells, or vaguely discuss tissue rejection. Few will think of skin or earwax as immune components.
Ask also if we should always bring down a fever or counter an inflammation.
We do not live in a sterile world, nor should we want to. Our bodies are designed to combat an intrusive world. We have numerous examples of why this is true. Babies and children who grow up where reasonable cleanliness (but not sterility) is the norm have a much lower disease rate than babies and children who live in an overly-clean environment. When the immune system is not asked to function, it does not function. Sometimes this can lead to problems. Children who have been exposed to many antigens have developed antibodies that later function on demand. Children without these antibodies get sick. This is one reason why newborns in the hospital are no longer kept in a sterile environment. They are exposed to the "family germs" immediately and develop healthier immune systems as a result.
Gnotobiosis (life in a sterile environment) has other deleterious effects also. Rats and mice are often raised gnotobiotically for research purposes. These animals often have misshapen internal organs. They also have a high rate of cancer development. Perhaps the interaction of the human body, the normal flora, and the immune system is far more intertwined and coevolutionarily involved than we would have ever thought possible.
C. Hints Related to Specific Chapter Topics
- I. Be certain the students have solid definitions of both antigen and antibody. These were covered in Chapter 5 but some students will have forgotten. Note the differences between specific and nonspecific defenses.
- II. Listing the nonspecific defenses can be quite dramatic. In discussing tears, note that all body parts exhibit an outflowing, or lavage.
- II.A. Phagocytosis can easily be compared to amoeboid movement.
- II.B. Ask if tissue inflammation is necessarily a bad thing.
- II.C. Compare the discussion of histamine with the allergic responses. How do histamine and anti-histamine work?
- II.D. I suggest you list the reasons why fever is a protective mechanism. Ask if we should always try to "bring down a fever." Of course, the question becomes, "How do we know when we should or should not countermand a fever?"
  An interesting point: Sometimes the fever inhibits the proteins (or enzymes) the invading pathogen produces. This gives the rest of the immune system a chance to attack the pathogen.
- III.B. The steps in the immune response are quite interesting. They are also a challenge to students who have never had this material before. If you are going to require specific knowledge, I suggest you know the material thoroughly yourself and then use Figures 39.5 through 39.13 to explain what is happening. Some students will need help with this material.
- III.B.2. One way to remember the five antibodies is to remember MADGE. If you really get into the antibodies, note that there are several antibody subtypes. Students could research this.
- IV. This section is really quite interesting and could be a topic for outside research. Traces of immunoglobins are present very early in fetal development, even though the system does not mature until later.
  If a physician suspects a newborn may have a disease caused by a pathogen that can cross the placenta (such as syphilis), a blood sample may be taken to determine the infant's antibody titer. If the IgM level is high, the indication is that the child has been producing this antibody even before birth in response to the pathogen.
- V.A. Keep AIDS in perspective. This is a serious disease; it is a universal tragedy. We will probably lose 10 million people in this country alone to AIDS. Keep your discussion about AIDS on what we know and don't know. This is a disease that touches everyone. And everyone in your class will know someone who has AIDS or has had AIDS. You may even have students before you who have the virus.
  Someone may tell you that being celibate and not doing drugs will keep a person from contracting AIDS. Ask what would happen if that person were in an automobile accident tonight and received a blood transfusion. Yes, blood is safer now that it has ever been, but still.... We are all affected by AIDS.
  Relate this material to the AIDS discussion on pages 253-255. Study Biology in Action 39.1. Challenge your students with the problems connected with finding a vaccine, or a cure. Consider, especially, the fact that the virus takes up residence inside the human cell. How can it be targeted?
  Chances of becoming infected with HIV upon exposure (in a way conducive to transmission) range from 1 in 2 to 1 in 500, depending on the individual's physical (immune) status, the quantity of virus entering the body, and the virulence of the particular strain of HIV.
- V.B. Another good challenge is to find out more about David Vetter. What advances have been made in recent years to combat SCID?
- V.C. We don't really know very much about chronic fatigue syndrome. Ask why Lewis suggests that the syndrome may be viral. Then ask why it may not be viral.
- VI.B. An interesting research question is: Are we more susceptible to allergies today than we were in the past? If so, why?
  Students are always amazed to learn what an allergy really is.