Lesson 11.2 Introduction to the chapter

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Introduction to the lesson

The immune system is one of the most important systems in the body. Without it, the body is weak and unable to stand against the continual attack of pathogens. A helpful analogy is to think of the immune system as a defense force, similar to that of a country. There is the external defense system which can be seen as similar to the walls and border controls of a country. The internal defense system consists of the cells which, like army or police officers, patrol the body, constantly on the look-out for pathogens. In this lesson, we will study the external defense system as well as a brief overview of the internal defense system. In the next lesson, we will study the cells of the internal defense system in detail.

 Reading

Read the pink box "Smallpox was first; polio second?" on p.223 of your text book.

Thinking it through

• Find out if your parents were vaccinated against smallpox. Were you?
• Were you vaccinated against polio?
• How is the polio vaccine administered?
• Find out the vaccination regime carried out in South Africa.
• What are some of the recent concerns about vaccinations? Is there any research to substantiate or reject the claims? What are/could be the consequences of such claims?
• Why do you think polio has been eradicated in the Western hemisphere?
• Why do you think polio still persists in countries like Nigeria, Somalia and Pakistan?
• Read up on the progress of polio campaign by searching online for “polio eradication”.
  
  

Defense against disease

Read the section from p.223-224 of your text book (including the untitled section, "Eternal defence system" and "Internal defence system"

 Definitions and review