1. 3.2 Factors Affecting the Immune System
Ch 3 – The Immune System
3.2 Factors Affecting the Immune System

2. Immunity
Recall: if our bodies contain the antibodies for specific antigens, we have what is called “immunity”.
We develop immunity when we get sick and our body makes antibodies to fight an antigen.
We can also obtain immunity by receiving a vaccine (vaccination).

3. Vaccines A vaccine is a special version of an antigen.
It is a weakened form of the disease
Administered by needle usually (liquid form)

4. How do vaccines work?
A small amount of weakened disease enters the body
Your immune system creates antibodies to fight the disease
You don’t become ill because there is such a small amount of weakened disease
But some antibodies remain…
They can be reactivated if the antigen enters your body in the future

5. More about vaccines
Vaccines can be a one-shot deal or you may get another vaccination every few years.
For example, we get tetanus shots every 10 years to bolster antibody production.
Some vaccines you receive as a baby

6. Are vaccines risky? No, not generally
Most vaccines are accompanied by mild side effects that don’t last long
Sometimes a severe allergic reaction can occur but this is rare.
Extreme reaction to smallpox vaccine

7. Disorders of the Immune System
Some people have an unusually high sensitivity to a certain substance.
When the substance enters their body, the immune system recognizes it as an invader and the system over-reacts!
This sensitivity is called an allergy

8. Allergies There are many things that can cause allergies.
Food (milk, gluten, peanuts, strawberries…)
Pollen, dust
Cats, beestings
Any substance that causes an allergic reaction is called an “allergen”.

9. Did You Know?
Dust allergies may actually be due to the feces of dust mites that live in house dust!
Dust mites eat dead skin flakes and make their home in your bed, carpet and old clothing!

10. Allergy Symptoms Common symptoms of an allergy Runny nose Watery eyes
Why does this happen?
When your body needs to fight an invader (an allergen) it releases a chemical called histamine
Runny noses and watering eyes are side-effects of histamine
We use drugs called anti-histamines to reduce these symptoms

11. Severe Allergic Reactions
Some people have more severe allergies
Ex: peanuts, bee-stings
If they come in contact with these allergens they can have a severe reaction called anaphylactic shock
Results in swelling, difficulty breathing, can be fatal
People often carry adrenaline-shots (EpiPen) to reduce the effects.

12. Disorders of the Immune System
AIDS
Acquired Immunodeficiency Syndrome
Infection of the immune system that can lead to death
Caused by a virus called human immunodeficiency virus (HIV)
HIV is a fierce pathogen that attacks the immune system and destroys it

13. What does HIV do to the body?
HIV infects helper T cells
Since helper T cells activate B cells, your body can no longer activate B cells or killer T cells
The immune system has no way to fight the pathogen
In other words, the immune system shuts down
Other antigens or pathogens can enter and your body has no way to fight against them

14. How is HIV transmitted? HIV can be transmitted through
Blood
Semen
HIV cannot be transmitted through
Direct contact
Shaking hands
Saliva
Sharing drinks, kissing

16. Cure for AIDS? There is currently no known cure for AIDS
HIV keeps changing its structure slightly
There are also several forms of the virus
A person infected with HIV live 4-10 years
AIDS currently affects more than 40 million people

17. Keeping Your Immune System Healthy
What can you do?
Eat healthy foods
Exercise
Wash your hands
Keep yourself and your home clean
Avoid drugs/ tobacco
Get enough sleep
Get vaccinations
Be cautious (don’t share drinks, etc..)