“What if pathogens get in?”• White blood cells take over and specifically identify and eliminate the pathogen.• White blood cells = “soldiers”• Immune Response
Organs of the Immune System White blood cells called leukocytes Made thymus and bone marrow Stored tonsils, spleen, and lymph nodes.
How does your body know there is an invader?• All pathogens have “distinct” antigens.• Antigens are marker proteins- trigger immune response• Your body must recognize antigens in order to identify and defeat the pathogen.• Normal cells also have antigens. Antigen
Antibodies• Your white blood cells produce antibodies in response to specific antigens.• These are specific to each pathogen.• All pathogens are unique, your immune system has to prepare a specific defense against each invader.• If you makes/have the antibodies it can kill the pathogen and you can fight the infection.• B-cells (type of white blood cell) make the antibodies!
Building “Immunity”• What happens if a pathogen makes it past the first lines of defense and avoids the inflammation response?• Your body must “actively” fight the disease.• This takes time.• This requires a special group of white blood cells lymphocytes.
“The Soldiers”• Many types of WBC work together during the immune response to fight the infection.• Macrophages• Lymphocytes
“The Soldiers”• 3 major classes of lymphocytes: 1) B-cells (plasma cells) 2) T-cells -Helper T cells -Killer T cells -Suppressor T cells 3) Memory cells
Step #1 “Invader Identification”• Macrophages identify pathogen, eat it, display antigens, signal helper T cells (interleukin-1).• Body temperature will increase (interleukin-1) in attempt to slow down pathogen.
• Helper T cells release interleukin 2 – signals help other leukocytes (other T-cells and B-cells)
Step #2 “Cloning Phase”• B cells make antibodies - lock onto antigens.“Marked for death.” Antibodies Antigen
Step #3 “The Attack Phase”• Killer T cells kill infected body cells.
Step #3 “The Attack Phase”• Macrophages clean up- eating pathogens, damaged body cells, etc.• Suppressor T cells “call off the troops” stopping the immune response.
Step #4 “Memory Phase”• Memory cells “remember” the attack and recognize a pathogen if it re-enters body.• Primary vs. secondary immune response
Active vs. Passive Immunity• Active = your body must fight off the disease to build up antibodies. Ex.) Fighting an infection or Vaccination• Passive = receiving antibodies from an outside source. Ex.) Breast feeding