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Your Body’s Defenses: Section 5
Teacher Notes
Lines of Defense
1. Enzymes
2. Skin
3. Immune System
Immune System
Cells and tissues that recognize and attack foreign substances in
the body.
Macrophage
An immune system cell that engulfs pathogens and other
materials.
T Cell
An immune system cell that coordinates the immune system and
attacks many infected cells.
B Cell
A white blood cell that makes antibodies.
Antibody
A protein made by B Cells that binds to a specific antigen.
Each antibody only attaches to one kind of antigen.
Antigen
Substances that stimulate an immune response.
Responding to a Virus
Step 1: Two Paths
Path 1: Virus particles are engulfed by macrophages.
Path 2: The body is infected by a virus.
Step 2: Two Responses
Response 1: A T cell response
Response 2: A B cell response
Step 3: T Cell Response
Helper T cells activate killer T cells.
Step 4: Destroying Infected Cells
Killer T cells recognize the viral antigen on infected cells.
The killer T cells destroy the infected cells so that the virus
particles inside the cell cannot reproduce.
Step 5: B Cell Response
Meanwhile, helper T cells also activate B cells. Activated B
cells divide to make cells that can make antibodies. The
antibodies recognize the shape of the viral antigen.
Step 6: Destroying the Virus
Antibodies bind to the viral antigen on the viruses. The
antibodies bound to the viruses cause the viruses to clump
together. Clumping marks the virus particles for
destruction.
Fevers
Response by the immune system started from a signal from the
helper T cells to the brain.
Help B cells and T cells multiply faster.
Memory Cells
B cells and T cells that remember a specific pathogen from a
previous infection.
Memory B Cell
B cells that are cells in your immune system that “remember” how
to make an antibody for a particular pathogen.
Allergy
A reaction to a harmless or common substance by the body’s
immune system.
Autoimmune Disease
A disease in which the immune system attacks your own cells.
Examples: Rheumatoid Arthritis, Type 1 Diabetes, Multiple
Sclerosis, and Lupus
Cancer
A disease in which the cells begin dividing at an uncontrolled rate
and become aggressive.
AIDS
Auto Immune Deficiency Syndrome
HIV
Human Immunodeficiency Virus
Uses the immune system to attack the body.
Homework – Your Body’s Defenses Section 5
Using Key Terms
Complete each of the following sentences by choosing the correct term from the
word bank.
Antibody
Infectious Disease
Noninfectious Disease
Pathogen
Cancer
B cell
T cell
Allergy
1. A(n) infectious disease is caused by a pathogen.
2. Antibiotics can be used to kill a(n) pathogen.
3. Macrophages attract helper T cells.
4. A(n) antibody binds to an antigen.
5. An immune-system overreaction to a harmless substance is a(n) allergy.
6. Cancer is the unregulated growth of cells.
Understanding Key Ideas – Multiple Choice
7. Pathogens are
a. all viruses and microorganisms.
b. viruses and microorganisms that cause disease.
c. noninfectious disease.
d. all bacteria that live in water.
8. Which of the following is an infectious disease?
a. allergies
b. rheumatoid arthritis
c. asthma
d. a common cold
9. The skin keeps pathogens out by
a. staying warm enough to kill pathogens.
b. releasing killer T cells onto the surface.
c. shedding dead cells and secreting oils.
d. All of the above
10. Memory B cells
a. kill pathogens.
b. activate killer T cells.
c. activate killer B cells.
d. produce B cells that make antibodies.
11. A fever
a. slows pathogen growth.
b. release helper T cells.
c. live in the gut.
d. engulf pathogens.
12. Macrophages
a. make antibodies.
b. release helper T cells.
c. live in the gut.
d. engulf pathogens.