1. The Immune System

2. Before the 1900’s, no one knew what caused sickness and infection
Most people thought evil spirits, swamp gas, or bad luck caused disease

3. science history Robert Koch Louis Pasteur Joseph Lister
Began linking certain pathogens to certain illnesses. Example: botulinum causes food poisoning.
Theorized that microbes caused infection. One of the first surgeons to disinfect instruments.
Theorized that microbes caused disease and killing them could prevent illness.

4. Functions To keep out or to fight pathogens that enter your body.
To recognize and attack foreign substances in the body.

5. organs
skin
white blood cells
macrophage
T cell
B cell

6. pathogen – something that causes illness
pathogen – something that causes illness. Pathogens can be a virus, bacteria, protein, fungi or protist.
protein
virus
bacteria
fungi
protist

7. external defenses
Your body’s first line of defense against pathogens is to create a barrier.
skin
breathing passages
mouth
stomach

8. skin
Your skin acts as a barrier to keep pathogens out.

9. breathing passages
Small hairs in your nose and trachea help trap pathogens.
They can cause you to sneeze or cough to try and expel the pathogens.

10. mouth and stomach Saliva and stomach acid can kill some pathogens.
Vomiting can also expel pathogens.

11. internal defenses
If a pathogen makes it past the external defenses, the internal defenses begin;
inflammation – happens with cuts and injuries
fever – body raises your temperature to try and kill the pathogens.
immune response – white blood cells are produced.

12. Immune response
white blood cells – cells that travel though the bloodstream and body searching out pathogens. The three types are macrophages, T cells and B cells.

13. macrophages
Destroys pathogens by engulfing and digesting them.

14. T Cells
Helper T cells travel throughout the body looking for pathogens.
Killer T cells attack certain pathogens.

15. B Cells B cells produce chemicals (antibody) that destroy pathogens.
Antibodies fight disease.

16. the immune response A pathogen enters the body
A macrophage finds it, engulfs and destroys it.
A helper T cell finds it
activates a killer T cell destroys the pathogen
finds a B cell to release antibodies to destroy the pathogen

18. building immunity
The body builds immunity against a disease when it is exposed to pathogens.
immunity – the ability to resist or recover from an infectious disease. You are born with some immunities, develop some from being exposed to pathogens and can be vaccinated for others.

19. building immunity
Your body has billions of T and B cells but it doesn’t produce very many for each pathogen.
Once you are exposed to a certain pathogen, like chicken pox, your T and B cells produce memory cells.
The next time you are exposed to that pathogen, the memory cells trigger the production of a large number of T and B cells for that pathogen.

20. vaccination
vaccine – a substance prepared from killed or weakened pathogens that is introduced into the body to provide immunity.
The vaccine triggers the body to make memory cells.
Edward Jenner was the first scientist to create a vaccine. It was for small pox.

21. challenges to the immune system
A healthy immune system is very good at keeping us from being sick.
However, we are exposed to challenges to out immune systems all the time.
allergies
cancer
immune deficiency
auto-immune disease

22. allergy - disorder in which the immune system is overly sensitive to a foreign substance.
pollen
dust
mold
food
medicine
animals

23. cancer - disease in which cells multiply uncontrollably, destroying healthy tissue.
Can exist in a tumor or can spread in the blood.
Cause:
genetics
chemicals

24. immune deficiency – some disease cause the immune system to become weak.
The most common for humans is HIV which is the virus that causes AIDS. It causes the immune system to fail.

25. HIV Virus The virus that causes aids
The virus gets into T cells and reproduces inside of them
As the T cells die, the body loses it’s ability to fight disease

26. auto-immune disease – a disease in which the immune system attacks itself.
Rheumatoid arthritis is one example.

27. Preventing Infectious Disease
Don’t share items that touch your mouth
Wash hands frequently
Cover mouth when sneezing or coughing
Get 8 hours of sleep
Eat a well-balanced diet
Regular exercise