1. How does the Body Protect Itself?
The immune System

2. How does your immune system work?
Ted ed video
emma-bryce

3. (c) McGraw Hill Ryerson 2007
Immune System
When the body is invaded by a foreign substance, the body recognizes it as not belonging and will mount an attack.
An Antigen is any non-living particle the body recognizes as foreign
A Pathogen is any disease causing agent (living or non- living: virus, some bacteria, parasites, etc)
The body has three lines of defense in defending against pathogens. a foreign molecule capable of inducing an immune response).​
(c) McGraw Hill Ryerson 2007

4. The Players: Skin, White Blood Cells and Antibodies
Barriers – skin, acid, oils, hair
Macrophages – (phagocytes) engulf foreign invaders
T Helper cells - stimulate B cells and Killer T cells
Killer T cells - recognize and kill bodies own cells that are infected
B cells – produce antibodies
Antibodies – protein markers

5. (c) McGraw Hill Ryerson 2007
First line of Defense
Skin
a physical barrier pathogens off.
The sweat and oils on skin are slightly acidic.
Gastric juices in your stomach can destroy some pathogens.
Mucus and cilia (microscopic hairs) in your nose and throat prevent pathogens from entering your respiratory system.
that stops most pathogens from entering the body.
The skin is waterproof so you can wash
See page 102
(c) McGraw Hill Ryerson 2007

6. Describe what each of the following “entry points” do to prevent entry of pathogens into the body:
Entry blocked by…
Eyes
Tears, eyelashes
Ears
Ear wax
Nose
Mucus, cilia
Mouth (and stomach)
Gastric juice

7. Infection
If pathogens are able to get past the first line of defence, for example, through a cut in your skin, an infection develops.
The second line of defence is a group of cells, tissues and organs that work together to protect the body. This is the immune system.

8. Ted Ed video: Cell vs Virus

9. Second line of Defense: Innate Immune Response
A response you are born with.
The response is quick,
Nonspecific (same for any pathogen)
Macrophages (Phagocytes) engulf (surround) and kill pathogens in a process called phagocytosis.
See page 102
(c) McGraw Hill Ryerson 2007

10. Characterized by Inflammation:
Pain, redness, swelling, heat
Fluid flows in to site of infection.
This allows phagocytes to enter area and attack pathogen
Phagocyte attacking bacteria:
ubCIcAh4M
Fluid flowing in creates swelling
See page 103
(c) McGraw Hill Ryerson 2007

11. Third Line of Defense: Acquired Immune Response
highly specific attack on a specific pathogen or antigen.
Involves B-cells and T-cells and antibodies.
All acquired immune responses help give you active immunity.
This means your body remembers how to fight a pathogen that has infected it before.
This is why you get diseases such as chicken pox only once.
Chicken Pox
See page
(c) McGraw Hill Ryerson 2007

12. How does it work?
It begins with an ANITGEN (a foreign molecule capable of inducing an immune response).
The term "antigen" comes from ANTI-body GENerating substances.

13. Step 1: Recognition - Antigen detected by phagocyte
Phagocyte engulfs (eats) the invader
Phagocyte presents part of the antigen on its surface
This signals Helper T cells (type of white blood cell),
T Cells become activated
Recognize antigens or pathogens on the surface of macrophages and stimulate B cells and Killer T cells.

14. (c) McGraw Hill Ryerson 2007
Killer T cells
Recognize and kill the body’s own cells that have been invaded by pathogens, preventing the pathogen from reproducing in the cell and then infecting
other cells.
Killer T cells also kill cancer cells.
(c) McGraw Hill Ryerson 2007

15. Step 2. Mobilization
The activated T cells divide to produce clones (copies of themselves).
Helper T cells stimulate B cells to divide, to also produce clones of themselves.
Some B cells become Plasma cells
Some B cells become Memory cells

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3. Disposal
Plasma cells make antibodies, which bind to antigens to make them harmless or mark them for destruction by other white blood cells
the antibody is specific to the invading antigen
 like a lock and key 
This can take time – 
this is why you can be sick for days/weeks.
(c) McGraw Hill Ryerson 2007

17. (c) McGraw Hill Ryerson 2007
4. Immunity
Some B cells become Memory cells will remain in the body for years. 
Because they are clones of the first activated B cells, they have “memory” of that particular pathogen and will immediately recognize it to mount a fast attack, quickly neutralizing it before it take hold.
This is how we become immune to certain diseases like chicken pox.
(c) McGraw Hill Ryerson 2007

18. Immune Response (4 Steps)
See page 105
Take the Section 3.1 Quiz
(c) McGraw Hill Ryerson 2007

20. Antibodies inactivate antigens by binding to them.
Antibodies are Y-shaped proteins that circulate through the blood stream and bind to specific antigens, thereby attacking microbes.
The body contains millions of different B cells, each able to respond to one specific antigen.

21. Cytotoxic T Cell Pathway
The cytotoxic T cells recognize antigens on the surface of infected body cells.
The cytotoxic T cells bind to the infected cells and secrete cytotoxins that destroys the infected cell.
/chapter24/animation__cytotoxic_t- cell_activity_against_target_cells__quiz_1_.html

22. T Cell Pathway
T-cells can either directly destroy the microbes or use chemical secretions to destroy them.
At the same time, T cells stimulate B cells to multiply and produce antibodies and memory B cells.
If the same antigen enters the body later, the memory B cells divide to make more plasma cells and memory cells that can protect against future attacks by the same antigen.
When the T cells activate (stimulate) the B cells to divide into plasma cells, this is called antibody-mediated immunity.
/chapter24/animation__the_immune_response.html

23. (c) McGraw Hill Ryerson 2007
Videos
Ted ed three lines of defence
Immune system explained Kurzgesagt Part I bacteria
Immune system KidsHealth
KidsHealth How Immune system works
Sneeze:
Ted ed How are germs spread goldilocks sick-yannay-khaikin-and-nicole-mideo
Reading Check #1-6 pg 106
(c) McGraw Hill Ryerson 2007

24. Disorders of the Immune System
ALLERGIES:
An allergy is an unusually high sensitivity to a substance.
Any substance that causes an allergic reaction is called an allergen. (common allergens: milk, pollen, dust)
Side effects of an allergic reaction are a result of histamine. Histamine is a chemical that your body releases when you need to fight invaders. (common symptoms: runny nose and watery eyes)
Severe allergies can cause anaphylactic shock (swelling, breathing difficulties, and sometimes death).

25. III. AIDS/HIV
Acquired Immunodeficiency Syndrome (AIDS) is an infection of the immune system that leads to health complications and often death.
AIDS is cause by the human immunodeficiency virus (HIV) that attacks the immune system by infecting Helper T-cells.

26. AIDS

27. AIDS/HIV AIDS is transmitted by blood and semen.
There’s no cure for HIV/AIDS, but a variety of medications can be used in combination to control the virus.

28. Why it’s so hard to cure HIV

29. Taking Care of your Immune System
Eat a well-balanced diet
Maintain personal hygiene (bathing, washing hands, brushing teeth)
Keep home clean
Avoid tobacco and other non-prescription drugs
Get plenty of rest and exercise
Keep vaccinations up to date
Do not engage in activities that involve sharing body fluids with others.

30. Immune Response Comic Strip
(c) McGraw Hill Ryerson 2007