Topic: Immunity
Aim: Describe how your immune system works to defend your body against pathogens.
Directions: Read the passage below. Use textual evidence to answer questions 1 – 13.
You might not realize it, but you come into contact with harmful substances constantly. Because your body has
ways to defend itself, you don’t even notice. One of the body’s best defenses is to keep foreign materials from entering in
the first place. The integumentary (skin), respiratory, and digestive systems are the first line of defense against or
disease-causing agents. Pathogens can enter through your skin, the air you breathe, and even the food you eat or liquids
you drink.
Sometimes foreign materials manage to get past the first line of defense. When this occurs, the immune system
responds in two ways. The white blood cells that first respond to the site of injury or infection attack foreign materials
in a nonspecific response. Some of these cells attack foreign materials and produce chemicals that help other white
blood cells work better. The second part of the response is very specific to the types of pathogens invading the body.
These white blood cells produce antibodies specific to each pathogen and provide your body with immunity.
Specific immune responses differ from nonspecific responses. First, specific responses are triggered by antigens.
An antigen is a protein on a cell’s surface that indicates whether the cell is from your body or is a foreign material.
When a foreign antigen on a pathogen enters the body, B lymphocytes produce antibodies to help destroy the
pathogen. Antibodies attach to the foreign antigens, marking the pathogens for white blood cells to help destroy them.
If the same pathogen enters the body again, the immune system can respond much more quickly. The B lymphocytes
recognize the foreign antigen already exists, and antibodies will be produced more quickly.
After your body has destroyed a specific pathogen, B cells that fight that pathogen remain in your system. If the
same pathogen were to enter your body again, your immune system would almost certainly destroy it before you
became ill. This resistance to a sickness is called immunity and it takes two forms: passive and active. When babies are
first born, they have only the antibodies transferred to them by their mothers during pregnancy or through breast milk.
They have not had the chance to develop antibodies of their own. This type of immunity is called passive immunity.
Antibodies are not produced by the person’ own body but given to the body from another source. Babies develop their
own antibodies after a few months. You have active immunity whenever your body makes its own antibodies. Your
body will again fight against any specific pathogen you have developed antibodies against. For example, it is most
unlikely that you will get chicken pox twice.
Another way to develop active immunity is to receive a vaccine that contains small amounts of weakened or
dead pathogens that stimulate an immune response. Your B cells are called into action to create antibodies as if you
were fighting the real illness. The pathogens are usually weakened or dead so that you will not get sick, yet they still
enable your body to develop an active immunity.
Today we have vaccines for many common pathogens. Most children who are vaccinated will not get many
diseases that their great grandparents, grandparents, and even parents had. Vaccinations can be administered by
injection or by mouth. Babies are not the only ones who get them, either. You can be vaccinated at any age.
Questions:
1. Which three systems provide the body with its first line of defense against pathogens?
_________________________________________________________________________________________________________________________________
2. Identify what is produced when foreign get past the first line of defense. ____________________________________________
3. Identify the protein on pathogens that your body does not recognize. __________________________________________________
4. Identify what attaches to the antigen on the pathogen. ___________________________________________________________________
5. Identify the type of white blood cell that produces antibodies. ___________________________________________________________
6. Describe immunity._____________________________________________________________________________________________________________
7. Identify the TWO types of immunity. _________________________________________________________________________________________
8. Identify the type of immunity that occurs when antibodies are not produced by the person’ own body but given
to the body from another source. ______________________________________________________________________________________________
9. How can a person develop passive immunity? _____________________________________________________________________________
___________________________________________________________________________________________________________________________________
10. Identify the type of immunity developed when the body produces its own antibodies. ______________________________
11. Identify the TWO ways you can develop active immunity.
____________________________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________________________
12. Identify what makes up a vaccine. ____________________________________________________________________________________________
13. Explain why a vaccine causes active immunity. _____________________________________________________________________________
___________________________________________________________________________________________________________________________________
Review:
1. Resistance to a specific disease is a(n)
a. antibiotic.
b. immunity. c. white blood cells.
d. addiction
2. Once you have had the chicken pox, it is unlikely that you will ever get the disease again because your
body has developed a(n)
a. passive immunity.
b. addiction.
c. active immunity.
d. antibiotic.
3. Which of the following parts of the body's defense system seeks out and destroys bacteria?
a. mucus
b. white blood cells
c. skin
d. red blood cells
4. Substances made by the body to protect itself from foreign bodies are called
a. antibodies
b. immunity
c. cilia
d. antibiotics
5. A _____________ is a substance that is injected into an organism to increase its immunity .
a. bacteria
b. antibodies
c. virus
d. antibiotics
6. Part of the body’s first line of defense against disease-causing organisms is
a. the immune system
b. the skin
c. antibodies
d. interferon
7. Molecules that are foreign to your body are called ______.
a. antibodies
b. white blood cells
c. antigens
d. histamines
8. A(n) ______ is a substance made by an organism in response to invading substances and disease-causing organisms.
a. allergen
b. antibody
c. antigen
d. pathogen
9. Immunity that occurs when a body makes its own antibodies is called _________immunity.
a. Passive
b. Temporary
c. Shortened
d. Active
10. Immunity that occurs when antibodies come from another organism is called __________ immunity.
a. Passive
b. Active
c. Permanent
11. An injection of a weakened virus that allows one to develop immunity against a disease is called a
a. antibody
b. vaccine
c. epidemic
d. pathogen