1. The Immune System
Small Pox
A white blood cell eating bacteria.

2. The Immune System
Slide # 2
The immune system is a defense system against foreign invaders (pathogens)
Immune system consists of a variety of different types of white blood cells (WBC’s)
White blood cell eating bacteria

3. The SKIN: The First Line of Defense
Slide # 3
The SKIN: The First Line of Defense
1. The skin is the most important first line of defense
a. Top layer is dead cells; prevents pathogens from entering
b. Sweat & tears have enzymes that prevent bacterial growth
2. Mucus that lines the nose, throat, & lungs traps pathogens
3. Pathogens and mucus are swept into stomach where stomach acids destroy them
Layers of Skin

4. Inflammatory Response: Second line of Defense
Slide # 4
Inflammatory Response: Second line of Defense
Nonspecific response to a localized infection.
Injured or infected cells cause blood vessels to enlarge so they can leak fluid & WBC’s
a. skin appears red at injury site
b. swelling occurs around infection
3. Macrophages (large WBC’s are first to arrive)
a. Nonspecific: treat all pathogens the same
b. Consume (eat) dead cells & pathogens
4. Fever kills pathogens. Fever over 103°F is dangerous for humans.

5. White blood cell chasing a bacterium cell
Click on the picture to watch!

6. The Inflammatory Response
Slide # 6
 The Inflammatory Response
Wound
Skin
Phagocytes move into the area and engulf the bacteria and cell debris
Bacteria enter the wound
Capillary

7. The Immune Response: Vocabulary
Slide # 7
The Immune Response: Vocabulary
1. Immunity: capacity of the human body to resist specific pathogens by identifying foreign (non-self) antigens
2. Antigen: anything that causes an immune response
3. Lymphocytes: WBC’s involved in immunity and the immune response
a. Helper T cells, B cells, & Killer T cells
b. are specific; seek out & destroy specific pathogens
4. Immune Response: specific response to a infection that has spread through body triggered by the presence of antigens/pathogens

8. The Immune Response: The Third and Final Line of Defense
Slide # 8
1. Macrophages ingest pathogen; send out chemical signal to call Helper T cells to the site of infection
2. By the time Helper T cells arrive, macrophages have incorporated pathogen’s antigens onto its own cell membrane
3. Helper T cell attaches to antigens on macrophage & develops new binding site that recognizes foreign antigens (copies enemy’s information)
4. Helper T cell passes information to two different attack cells: B cells & Killer T cells

9. Immune Response T cell binds to activated macrophage
Slide # 9
Immune Response
T cell binds to activated macrophage
Helper T cell activates killer T cells and B cells
Macrophage
Helper T Cell
Killer T Cell
T Cell
T cell, activated by macrophage, becomes a helper T cell
Infected Cell
Antigens are displayed on surface of macrophage
Killer T cells bind to infected cells, disrupting their cell membranes and destroying them

10. Killer T Cells: Have Direct Contact with Antigens
Slide # 10
Killer T Cells: Have Direct Contact with Antigens
1. Killer T cells come into direct contact w/ a cell; pierces hole in cell wall
a. Water moves into the cell & the cell swells & bursts open
2. Killer T cells produced at same time as B cells
3. Killer T cells destroy protists, virus infected cells, & cancer cells

11. B Cells Produce Antibodies
Slide # 11
B Cells Produce Antibodies
B cells release antibodies
Millions of B cells are cloned & millions of antibodies are released into blood when fighting infection
Antibody: Y shaped protein that “tags” an antigen for destruction
Antibodies also bind to virus & bacterial toxins & neutralizes them
Antigen-binding sites
Antibody
Antigen
Antibody
Antigen

12. Active vs. Passive Immunity
Slide # 12
Passive Immunity is acquired when antibodies to the antigen are injected into the body. They do not last. (Ex. Breast milk)
Active immunity is produced when the body creates its own antibodies after being exposed to an antigen.
Acquired through vaccinations
Acquired through infection of pathogen.
Antibodies are constantly produced by memory cells created when the body was first infected.

13. Why you don’t get chicken pox twice.
Interval between exposures
First exposure
Second exposure
Time
Antibody Concentration

14. Immune System Disorders/Problems
Slide # 14
An allergy is a disorder in which the immune system overreacts to the presence of an antigen such as pollen.
An autoimmune disease is one in which the immune system attacks its own body cells. Ex. M.S. and Arthritis
Rejection of organ transplants (cells are foreign).
Cancer cells are naturally destroyed by the body; however, when the body fails to recognize them they spread causing tumors.

15. Cells of the Immune System
The body's innate defense against disease is natural immunity. The immune system consists of white blood cells, cell products, and other substances.

16. Cells of the Immune System
1. Lymphocytes include:
a. T cells (T for thymus, where they mature)
b. B cells (B for bone marrow, where they originate)
c. Natural killer (NK) cells (less abundant)
2. Macrophages & Granulocytes: Phagocytic or "cell-eating”
a. Neutrophils -- form an early line of defense against bacterial infections (Non-specific response) & involved in inflammatory response
b. Eosinophils -- Their natural role is to defend us against parasites; also release chemicals that damage lungs and contribute to asthma
c. Basophils -- involved in inflammatory response & allergic reactions
d. Mast cells settle in connective tissues and usually do not circulate in the blood stream. Release histamine; contributes to allergic reactions
Mast cell with Salmonella bacteria