1. The Human Immune System

2. What is the immune system?
The body’s defense against disease-causing organisms, viruses, malfunctioning cells, and foreign particles

3. The First Line of Defense ~Skin~
The dead, outer layer of skin, known as the epidermis, forms a shield against invaders and secretes chemicals that kill potential invaders

4. The First Line of Defense ~Mucus and Cilia~
As you breathe in, foreign particles and bacteria bump into mucus throughout your respiratory system and become stuck
Hair-like structures called cilia sweep this mucus into the throat for coughing or swallowing

5. The First Line of Defense ~Saliva~
Saliva contains many chemicals that break down bacteria
Thousands of different types of bacteria can survive these chemicals, however

6. The First Line of Defense ~Stomach Acid~
Swallowed bacteria are broken down by incredibly strong acids in the stomach that break down your food
The stomach must produce a coating of special mucus or this acid would eat through the stomach!

7. The Second Line of Defense ~The Inflammatory Response~
Injured body cells release chemicals called histamines, which begin inflammatory response
Capillaries dilate
Pain receptors activate
WBCs flock to infected area like sharks to blood

8. The Second Line of Defense ~White Blood Cells~
If invaders actually get within the body, then your white blood cells (WBCs) begin their attack
WBCs normally circulate throughout the blood, but will enter the body’s tissues if invaders are detected

9. White Blood Cells ~Phagocytes~
These white blood cells are responsible for “eating” foreign particles by engulfing them

10. The Third Line of Defense ~Antibodies~
Most infections never make it past the first and second levels of defense
Those that do trigger the production and release of antibodies
Proteins that latch onto, damage, clump, and slow foreign particles
Each antibody binds only to one specific binding site, known as an antigen

11. Lymphocytes (white blood cells)
T-Cells: identify pathogens by its markers or “antigens”
B-cells: produce antibodies or proteins that destroy the pathogen

12. What is immunity?
Resistance to a disease causing organism, virus, or harmful substance
Two types
Active Immunity
Passive Immunity

13. Active Immunity You produce the antibodies
Your body has been exposed to the antigen in the past either through:
Exposure to the actual disease causing antigen (chickenpox, for example)
Planned exposure to a form of the antigen that has been killed or weakened – vaccine

14. Vaccine
Antigens are deliberately introduced into the immune system to produce immunity so body will have antibodies ready to destroy pathogen if you get exposed later.
Because the virus or bacteria has been killed or weakened, minimal symptoms occur
Have eradicated or severely limited several diseases from the face of the Earth, such as polio and smallpox

15. How long does active immunity last?
It depends on the antigen
Some disease-causing viruses and bacteria mutate into new forms that our body doesn’t recognize. This requires annual vaccinations, like the influenza (flu) shot.
Booster shot - reminds the immune system of the antigen so you’re still protected.
Others last for a lifetime, such as chicken pox

16. Passive Immunity You don’t produce the antibodies
A mother will pass immunities on to her baby during pregnancy
These antibodies will protect the baby for a short period of time following birth while its immune system develops.
Other example-rabies antibodies when you are bitten but you must get treatment shots to cure it

17. Bacterial diseases
Bacteria are living cells and release toxins. Your body can’t kill bacteria so most must be treated with antibiotics to kill them
Some examples are strep throat, food poisoning, salmonella, etc.

18. Cell before infection…
Viruses
Viruses enter body cells, hijack their organelles, and turn the cell into a virus-making factory. The cell will eventually burst, releasing thousands of viruses to infect new cells.
…and after.
Cell before infection…

19. The Common Cold The common cold is caused by a virus.
It takes hours before you start having symptoms you are infected with a cold virus.
Your body’s immune response T cells start working to identify the pathogen and B cells make antibodies to immobilize it. This immobilization process can take a week and then you feel better.
Viruses can’t be killed with antibiotics since they are not living. You can take medicines like acetaminophen to relieve symptoms, but they don’t shorten your cold.
The cold virus mutates often, so you will never get the same cold again. There is no vaccine to prevent colds.

20. Aquired Immune Deficiency Syndrome
Caused by the Human Immunodeficiency Virus
Discovered in 1983
Specifically targets and kills T-cells
Because normal body cells are unaffected, immune response is not launched

21. AIDS ~The Modern Plague~
The HIV virus doesn’t kill you – it cripples your immune system
With your immune system shut down, common diseases that your immune system normally could defeat become life-threatening
Can show no effects for several months all the way up to 10 years

22. HIV/AIDS ~The Silent Spread~
Transmitted by blood, and fluids from infected people through sexual contact, blood trans-fusions, contami-nated needles.
As of 2014, an estimated 35 million people are living with HIV/AIDS. Sadly many don’t know or aren’t careful, so the spread continues.
So far there is no vaccine to prevent HIV/AIDS.