Fig. 14.1: Types of Immunity
|
Back Lesson 13
|
Home Cover Page
|
Top Lesson 14
|
Next Lesson 15
|
Lesson Fourteen: Immune System
Teaching suggestions: - Lecture, individual work, and group work activity.
A visual display (chart or sketch) of the role of each of these factors in the body’s defense system may help students grasp the basics of these concepts. This discussion may be expanded to include the role of the lymphatic system within the immune response. Students should explore and compare the ways in which immunity is acquired, both in passive (e.g. breast milk) and active (e.g. exposure, vaccines) ways.
Explain to students that they are to be the general in charge of troops in a war. Set up an analogy between war and the action of the human immune system. Allow students to work in pairs and use all available reference materials.
For activity closure, hold a teacher-led class discussion that includes direct instruction as needed to ensure student understandings of the immune system. Using appropriate reference materials, ask students to identify the components of the immune system that are compromised by the HIV virus. Discuss as a class how acquired immune deficiency syndrome (AIDS) affects all the body due to an ineffective immune system.
Pose focus questions
Whenever we are stepping in our bare feet we are being exposed to germs. Fortunately, for most of us, the immune system is constantly on call to do battle.
It is our immune system that enables us to resist infections. In most cases, the immune system does a great job of keeping people healthy and preventing infections. The immune system is the body's defense against infectious organisms and other invaders through a series of steps called the immune response. But sometimes problems with the immune system can lead to illness and infection. The immune system is composed of two major subdivisions, the innate or non-specific immune system and the adaptive or specific immune system. The innate immune system is our first line of defense against invading organisms while the adaptive immune system acts as a second line of defense and also affords protection against re-exposure to the same pathogen.
Group activity: Divide the class into four groups and assign each group one of the following categories of immunities: (1) artificially, actively acquired, (2) artificially, passively acquired, (3) naturally, actively acquired, and (4) naturally, passively acquired. Instruct each group to research their assigned topic and prepare a poster and oral presentation for the next class. The report should include who receives the antigen (any substance that causes a specific immune response), who or what produces the antibody, the duration of the immunity, the side effects and consequences of being exposed to the same antigen again, and an example for each type of immunity (e.g., hepatitis A immunization verses hepatitis B immunization, immunization received by a baby from mother, or immunization as a result of exposure to an infected person).
After oral presentation from each group representative, it is important to conclude with a class discussion. Sample items for discussion include,
The teacher is expected to explain the concept of antigens and antibodies.
Antigens are foreign substances that elicit a specific response by lymphocytes.
Antibodies are an antigen-binding immunoglobulin (protein), produced by B cells, that functions as the effectors in an immune response.
Antigens may be molecules exhibited on the surface of, produced by, or released from bacteria, viruses, fungi, protozoan, parasitic worms, pollen, insect venom, transplanted organs, or worn-out cells. Each antigen has a unique molecular shape and stimulates production of an antibody that defends specifically against a particular antigen.
Fig. 14.1: Types of Immunity
Immunity is the ability to resist infection by an invading pathogen. The body quickly launches an immune response and prevents the symptoms of disease occurring. This can happen in two ways naturally or artificially. Both natural and artificial immunity can be either passive or active.
Active immunityis the immunity conferred by recovery from an infectious disease. Depends on response by the person's own immune system, active immunity can be established as follows.
For immunization, vaccines may be inactivated i.e. bacterial toxins, killed microbes, parts of microbes, or viable but weakened microbes.
In all cases the organisms can no longer cause the disease but can act as antigens and stimulate an immune response. A person vaccinated against an infectious agent who encounters the pathogen will show the same rapid, memory-based secondary response as someone who has had the disease.
Passive immunityis a kind of immunity which has been transferred from one individual to another by the transfer of antibodies. Passive immunity is when a person is given antibodies produced by someone else. This could happen naturally when a mother passes her own antibodies to her baby either through her placenta or her breast milk. Another method of gaining passive immunity is artificially, for example when a person is given an injection of antibodies if they suspect that they have been exposed to a disease such as tetanus or diphtheria. In this situation, immunity is established immediately. This form of immunity is short lived as no memory cells are produced.
Long-term immunity is gained via active immunity. Examples of this involve the body being stimulated to produce antibodies via a specific immune response. This occurs either by a person contracting a disease which is referred to as natural active immunity or via an injection of weakened (attenuated) or dead antigens. In this case an immune response is activated resulting in the production of antibodies and memory cells. The latter form of immunity is called artificial active immunity.
Let the students discuss how HIV (Human Immunodeficiency Virus) severely affects the immune system of humans.
Acquired immunodeficiency syndrome is a severe immune system disorder caused by infection with the human immunodeficiency virus (HIV). Individuals with AIDS are highly susceptible to opportunistic diseases, infections, and cancers that take advantage of a deficient immune system.