Key QuestionsKey Questions  1. What are pathogens, and how do they affect living things?  2. What is the functions of the immune system, and how does it protect humans?  3. What is active and passive immunity?  What are antibodies, and how do they protect us?  What are vaccines, and how do they protect us?

The Immune SystemThe Immune System  1. Invaders to the body: A. Pathogens:  Viruses, bacteria, and other microorganisms that cause disease.

Pathogens are found in food, air, water everywhere!

‘Where Germs Really Thrive’  Question:  Which surface holds more germs, the top of a desk or the toilet seat?

‘Where Germs Really Thrive’  Answer: The top of a desk has 400 times more bacteria than the average toilet seat!  Info:  Computer keyboards have more germs than door handles.  Other high-germ areas:  Bathroom sinks  Clean laundry (if not washed in hot water)  Phones

The Immune SystemThe Immune System 2. Defense systems against pathogens: a. First Line Defenses:  Include physical and chemical barriers  Skin, sweat, mucus, tears, stomach acid, etc.

The Immune SystemThe Immune System b. Second Line Defenses:  If pathogen gets past 1 st line defense and starts an infection, the 2 nd line is activated.  Results in inflammatory response (swelling, redness, warmth)  Attracts phagocytes to come and ingest pathogens (non-specific).

Phagocytosis Video Clip on server: WBC Chasing Bacteria (30 sec.)

Phagocytes attacking Anthrax

The Immune SystemThe Immune System c. Third Line Defenses:  Immune System! (Specific)  Put into action when inflammatory response is insufficient.

The Immune SystemThe Immune System 3. Immune System:  A. Define Immunity: The ability of the body to resist or fight off disease.

The Immune SystemThe Immune System B. Define Antigen:  Any substance that can cause an immune response.  Bacteria and viruses have substances (such as proteins) on their outer surfaces that act as identifiers. (Also remember blood types).

The Immune SystemThe Immune System C.Define Antibody:  Proteins in the blood that bind to antigens to help destroy pathogens.  Immunity results from the production of antibodies specific to a given antigen. antibodiesantigen

The Immune SystemThe Immune System

Immunity results from the production of antibodies specific to a given antigen!!!

 Video Clip on server: Virus Invades Your Body (3:27)

The Immune SystemThe Immune System  Organisms acquire immunity in following ways:  1. Active Immunity: When body produces its own antibodies to attack a particular antigen. Occurs in response to either:

The Immune SystemThe Immune System a. Contact with the disease-causing organism. * For example: When a person is infected with the chicken pox virus for the 1 st time, the body develops antibodies against the organism. The antibodies then remain in the blood and protects the individual from infection by that same organism again.

The Immune SystemThe Immune System b.Vaccination:  Vaccine = injection with a solution that contains either dead or weakened disease organisms.  Stimulates body to develop antibodies through an immune response.  Organisms in vaccine are too weak to cause an infection.  Booster shots – given to “boost up” levels of antibodies in body.

The Immune SystemThe Immune System 2. Passive Immunity: Also called temporary or borrowed immunity. Immunity produced by introduction of antibodies themselves into body from blood of another person or animal.

The Immune SystemThe Immune System a.Maternal Immunity:  Antibodies from the mother enters the baby’s blood from the mother’s bloodstream or milk. Protects baby after birth while baby’s immune system is developing.

The Immune SystemThe Immune System b.Medications:  Examples – antibiotics.  Ex. Penicillin results in a temporary protection from disease-causing organisms.

And the answer lies in…And the answer lies in…

Question:  Why can we get some illnesses again, like the ‘flu’ if we’ve already had it?  Some pathogens have a high mutation rate.  So, if we were infected with a certain strain of influenza we developed antibodies against it.  But, if the virus mutated and we were exposed to the new strain, our body would see that as foreign and would have to make new antibodies.

History and InfluenzaHistory and Influenza  1918 Flu Virus – ‘Spanish Flu’  Deadliest epidemic in history  Killed 50 million people worldwide  Killed mostly young, strong, healthy adults  Immune systems were over-stimulated  Different from most flu viruses – infects cells deep in the lungs  Lungs filled with fluid (12 min.)

History and InfluenzaHistory and Influenza  1918 Flu continued…   Result of ‘gene swapping’  Occurs when a person is infected by 2 different influenza viruses at the same time  Viruses exchange genes – results in new virus that very few people have immunity to

History and InfluenzaHistory and Influenza  H5N1 – Bird (Avian) Flu  2004 – Scientists were concerned that H5N1 that infected birds could mutate, cross-over and infect humans  H5N1 is deadly much like the 1918 strain-kills younger people  They thought it could spark a flu pandemic

History and InfluenzaHistory and Influenza  H1N1 – Swine Flu  1 st US cases in 2009  Originally referred to as “swine flu” because laboratory testing showed that many of the genes in the virus were very similar to influenza viruses that normally occur in pigs (swine) in North America.  At risk – young and old and pregnant women

Seasonal VaccinesSeasonal Vaccines  Article

The Immune SystemThe Immune System E. Immune Responses:  1. Allergies a.Caused by production of antibodies in response to allergens such as dust, pollen, foods, etc. b.Allergens themselves are not dangerous. c.Antigens on allergens enter body and cause allergic response (runny nose, swollen eyes, etc.) d.Generally caused by release of substance by body called histamines.

The Immune SystemThe Immune System  Transplant Tissue a. If a person receives a donated heart from another individual, the body views it as “foreign” b.Immune system reacts by producing antibodies to fight off foreign invader. c. New medicines allow people to live with transplanted tissue by preventing the body from rejecting the tissue.

The Immune SystemThe Immune System **Problems with immune system – see AIDS packet.**

Using Bacteria in ArtUsing Bacteria in Art  Scientists are using bacteria that were trained in a lab to eat certain types of organic matter in order to restore art  Applied in a gel and sponged away after 90 minutes  Bacteria die without moisture and art is restored!