Illness, Immunity and Allergies

Science, Grade 6


Table Of Contents: Illness, Immunity and Allergies

1. When the Immune System Is Overwhelmed
Although your body has several levels of defense and an amazing immune response, you still experience sickness. This happens when cancer or the infectious agent, such as in pneumonia, grows beyond what our immune and inflammatory systems can fight, and illness wins out.
2. Immunization: Passive Immunity
There are ways in which our system can be boosted or immunized to protect us from pathogens. In cases of passive immunity, specific antibodies are injected into the bloodstream. For example, a person infected with rabies is injected with anti-rabies antibodies to acquire immunity. Another example of passive immunity happens naturally in a developing fetus as antibodies are passed from mother to fetus across the placenta.
3. Immunization: Active Immunity
Active immunization happens when a person receives an injection of weakened antigens in the form of a vaccine. The vaccine stimulates the B and T lymphocytes, and antibodies are produced. If the immunized person is exposed to or infected with that specific pathogen again, the immune system is ready to defend the body against the challenge. Each year many people are immunized with a flu vaccine to avoid the spread of a particular type of influenza.
4. Allergic Response
A person with allergies has an immune system that is hypersensitive to certain materials. When the immune system reacts or overreacts to materials such as dust, pollen, latex or certain foods, we call this an allergic reaction. Exposure to these materials, or allergens, produces an exaggerated response that can sometimes even threaten someone’s life.
5. Staying Healthy and Preventing Disease
Keeping healthy requires a combination of maintaining healthy defense systems and reducing our exposure to those materials that can make us sick. Frequent hand washing is a way to kill germs that can easily spread from person to person and reduce the risk of infection.