The Human Immune System Video

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

Pathogens Bacteria Viruses Parasites Fungi Protists Bacteria reproduce fast, by mitosis. If the immune system can’t handle them, antibiotics can be prescribed. Finish your prescriptions or the strongest bacteria survive!

Viruses Viruses require a host cell to reproduce. 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. Cell before infection… …and after.

The First Line of Defense -Skin -Mucus and cilia of respiratory system filter airborne pathogens -Saliva and Stomach Acid of the Digestive System kill swallowed bacteria

Second Line of Defense: ~White Blood Cells~ -White blood cells attack pathogens. -Phagocytes engulf and destroy pathogens with their lysosomes -T-lymphocytes destroy infected body cells -B- lymphocytes (memory cells) produce antibodies and remember how to make more antibodies later Video

Antibodies Antibodies are proteins produced by white blood cells that target specific pathogens. They have a specific shape that matches the antigens on the pathogen. Antigens are protein markers on the surface of the pathogen. “The flag” waved to say, come get me!

What is immunity? -Resistance to a disease causing organism or harmful substance (antigen)

Immunity -New antigens take longer to recognize. A person remains ill until a new antibody can be produced -Old antigens are quickly recognized, and antibodies are made. A person may never become ill from that invader again. The person is now immune to that specific illness (antigen).

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, usually causing you to get sick – You fought it, you won, you remember it -Vaccine introduces a form of the antigen that has been killed or weakened – You detected it, eliminated it, and remember it

Skin Wound Bacteria enter the wound Phagocytes move into the area and engulf the bacteria and cell debris Capillary

Cell-Mediated Immunity T Cell Helper T Cell Killer T Cell Infected Cell Antigens are displayed on surface of macrophage T cell binds to activated macrophage T cell, activated by macrophage, becomes a helper T cell Helper T cell activates killer T cells and B cells Prentice Hall Biology Presentation Pro, 2002 Macrophage Killer T cells bind to infected cells, disrupting their cells membranes and destroying them

Vaccine Antigens are deliberately introduced into the immune system to produce immunity Because the virus has been killed or weakened, minimal symptoms occur Memory B cells are produced; they will quickly produce antibodies if you come in contact with the virus again.

How long does active immunity last? It depends on the antigen Some disease-causing viruses mutate into new forms that our body doesn’t recognize, requiring annual vaccinations, like the flu shot Booster shot - reminds the immune system of the antigen Others last for a lifetime, such as chicken pox

Passive Immunity You don’t produce the antibodies –A mother will pass antibodies on to her baby during pregnancy and through breast milk –These antibodies will protect the baby for a short period of time

Immune Disorders ~Allergies~ -Immune system mistakenly recognizes harmless foreign particles, like dust or peanut proteins as antigens -Launches immune response, which causes sneezing, runny nose, and watery eyes -Anti-histamines block effect of histamines and bring relief to allergy sufferers

Organ Transplants & Blood Transfusions Transplanted organs present foreign proteins to the immune system that are recognized as antigens Immune suppressant drugs are prescribed to stop the immune response and organ rejection Blood cells present antigens and blood transfusions can also be rejected.

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

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

Infection; Immune system eliminates most of HIV Symptoms, such as swollen lymph nodes, are few Loss of immune function more apparent; appearance of characteristic diseases such as yeast infections Almost total loss of cellular immunity; AIDS Relative HIV concentration T cell concentration Years

AIDS ~The Silent Spread~ Transmitted by sexual contact, blood transfusions, contaminated needles As of 2007, it affects an estimated 33.2 million people