1. What happens when we get sick? Why do we get better?
THE IMMUNE SYSTEM
What happens when we get sick?
Why do we get better?

2. How does your body know when a substance is an invader?
At the heart of the immune response is the ability to distinguish between "self" and "non-self." Every cell in your body carries the same set of distinctive surface proteins that distinguish you as "self." Normally your immune cells do not attack your own body tissues, which all carry the same pattern of self-markers; rather, your immune system coexists peaceably with your other body cells in a state known as self-tolerance.

3. Functions of the Immune System
1. Recognize self vs. non-self
2. Destroy non-self

4. Foreign Invaders Antigen:
Any surface marker capable of triggering an immune response
An antigen can be on a virus or non-self cell
Bacteria, other people’s cells
Even allergens and cancerous cells
Don’t forget to mention allergens and cancerous cells as well.

5. ANATOMY OF THE IMMUNE SYSTEM
The immune system is localized in several parts of the body
immune cells develop in the bone marrow and thymus
immune responses occur in the secondary organs
Point out:
Thymus – glandular organ near heart – where T cells learn their job
Bone marrow – blood producing tissue located inside certain bones
Spleen – serves as a filter for the blood:
removes old and damaged red blood cells
removes infectious agents and uses them to activate cells called lymphocytes
Lymph nodes – small organs that filter out dead cells, antigens, and other “stuff” to present to lymphocytes
Lymphatic vessels – collect fluid (lymph) that has “leaked” out from the blood into the tissues and returns it to circulation

6. ANATOMY OF THE IMMUNE SYSTEM: The immune system is localized in several parts of the body
Spleen: filters and removes old and damaged red blood cells
removes infectious agents and uses them to activate cells called lymphocytes
Bone marrow: tissue insides bones that produces blood cells
B cells and T cells are types of white blood cells
Point out:
Bone marrow – blood producing tissue located inside certain bones
Spleen – serves as a filter for the blood:
removes old and damaged red blood cells
removes infectious agents and uses them to activate cells called lymphocytes

7. ANATOMY OF THE IMMUNE SYSTEM: The immune system is localized in several parts of the body
Thymus: T cells mature here (learn their job)
Lymph nodes: small organs that filter out dead cells, antigens, and other “stuff” to present to lymphocytes
Point out:
Thymus – glandular organ near heart – where T cells learn their job
Lymph nodes – small organs that filter out dead cells, antigens, and other “stuff” present in lymphocytes

8. ANATOMY OF THE IMMUNE SYSTEM: The immune system is localized in several parts of the body
Lymphatic Vessels: collects fluid (lymph) “leaked” from blood into the tissues and returns it to circulation
Tonsils: 3 pairs masses of lymphoid tissue- helps protect against bacteria around the throat
Appendix: “safe house” for the beneficial bacteria living in the human gut
Lymphatic vessels – collect fluid (lymph) that has “leaked” out from the blood into the tissues and returns it to circulation
Tonsils- 3 pairs masses of lymphoid tissue (pharyngeal, palatine, lingual)
- has become controversial to perform tonsillectomy due to the immunological role played by the lymphoid tissue
- helps protect against bacteria around the throat
Appendix- “safe house” for the beneficial bacteria living in the human gut

10. Non-specific defense mechanisms:
The body’s attempt to destroy all types of foreign invaders
General, not targeted to a specific pathogen (virus or bacteria)
Specific defense mechanisms:
Immune response specific for a pathogen

11. There are three lines of defense against infection
Point out to students that there are two general categories of defense:
Non-specific (born with it)
First line of defense – sweat, tears, saliva, mucous (chemical barriers) and skin, membrane lining body passages (physical barriers)
Second line of defense (inflammatory response) – swelling, redness, warmth, and pain in the area of infection. An increased blood flow attracts wbc’s (i.e. macrophages, phagocytes and neutrophils)
Specific – if a pathogen gets past the first two lines of defense, the immune system will react with the immune response
Immune response – At this stage the immune system is fully active in recognizing, attacking, destroying and remembering each kind of pathogen or foreign substances that enter the body. This step involves the production of antibodies and specialized cells that bind to and inactivate foreign substances

12. First Line of Defense: The outer layer of the body
Goal: prevent organisms from gaining access to the body
Details:
Physical barriers: skin, hair
Chemical barriers: sweat, tears, saliva, mucous, skin
These contain enzymes that break down cell walls of many bacteria

13. Second line of defense: Cells and proteins in our blood stream
Goal: recognize, neutralize and destroy invaders inside the body
Details: inflammation and fever (swelling, redness, warmth, pain)
Increased blood flow brings cells to fight infection
Macrophage, phagocytes, and neutrophils

14. Third Line of Defense: The Immune Response
Two types of cells are involved:
B cells: provide immunity against antigens and pathogens in the body fluids by making antibodies
This is called humoral immunity
Vaccines cause B cells to produce antibodies
T cells: provide defense against abnormal cells and pathogens inside living cells
This is called cell-mediated immunity

15. Putting it all Together
1. Virus infects body

16. Putting it all Together
2. Macrophage (WBC) eat virus and display viral antigen

17. Putting it all Together
3. White blood cell activates Helper T cell

18. Putting it all Together
4. Helper T Cells activate B cells and killer T cells

19. Putting it all Together
5. Some B cells become memory cells for future immune response, some become plasma cells

20. Putting it all Together
6. Plasma cells make antibodies which bind to viral antigen

21. Putting it all Together
7. Antibodies attach to the virus and infected body cells, signals for their destruction
Antibodies protect against foreign invaders

22. Putting it all Together
8. Killer T cells destroy infected body cells

23. 1. Virus infects body, cells display viral antigens
2. Macrophages engulf virus and display viral antigen
3. Macrophages activate helper T cells
4. Helper T Cells activate cytotoxic T and B cells
5. B cells form plasma cells
Some B cells become memory cells for immune response later on
6. Plasma cells make antibodies which bind to viral antigen
7. Antibodies attach to the virus and infected body cells, signals for their destruction
Antibodies protect against foreign invaders
8. Cytotoxic T cells destroy infected body cells

24. HIV (Human Immunodeficiency Virus)
Cause:
Human Immunodeficiency Virus
Symptoms:
Fever, headache, tiredness, enlarged lymph nodes
AIDS (Acquired Immunodeficiency Syndrome)
weight loss, fatigue, memory loss
Destroys Helper T cells (part of immune system)
body cannot fight off illnesses caused by bacteria, other viruses, fungi, or parasites.
Ultimately leads to death

25. HIV (continued) Treatment: Transmission: Status: Prevention:
Reverse Transcriptase (RT) inhibitors & Protease Inhibitors- stops the virus from making copies of itself
Transmission:
sexually (orally, vaginally)
Blood (needles, or through mucus membranes)
Breast milk mother to child
NOT from kissing, touching, insects bites
Status:
No vaccine, several medicines to prevent spread in body
Worldwide: In 2004, 40 million people living with HIV/AIDS, 5 million newly infected, and 3.1 million deaths
Prevention:
Abstinence, Safe sex (Condoms!), avoidance or risky behaviors associated with sex and drug use