Immune System Important system that helps fight off pathogens What is a Pathogen? Microorganism that causes infection or a disease: Bacteria Viruses Fungi Protists/Parasites Made of different types of cells each with a specific job including: a. Lymphocytes – White blood cells or WBC’s Target specific Pathogens

Types of Lymphocytes b. T - cells Identify Pathogens by recognizing their Antigens. What is their job? To activate B-cells c. B cells Produce chemicals called Antibodies d. Macrophages – Surround pathogen and digest or eat it Also called Phagocytes Pathogens

What are the Two Types of T– Cells? 1. Natural Killers Cells 2. Cytotoxic Cells * Destroy pathogens after they are marked by antibodies * Destroy cells that are infected with a virus * Also recognize cancer cells and destroy them What are Memory T- Cells ? They remember what type of antigens on a pathogen Help immune system recognize the pathogen if it invades our body again!! AMAZING ! ! !

ANTIGENS AND ANTIBODIES What are Antigens? Special proteins on surface of cells and pathogens They are recognized by the Immune System Why? So the White blood cells know which pathogens they need to destroy!!! W What are Antibodies? Special proteins that recognize specific Antigens on Pathogens Mark the pathogens for destruction by WBC’s

Pathogens What are Pathogens? Organisms that cause disease Infectious diseases are? Diseases that are caused by pathogens. When you have an infectious disease pathogens are inside your body causing harm Staphyloccocus aureus Staphyloccocus aureus Magnified 20,000X Magnified 20,000X About 1 um in size About 1 um in size What type of pathogen is Staph? What type of pathogen is Staph? BACTERIA BACTERIA

4 TYPES OF COMMON PATHOGENS Can you guess what they are? Viruses Fungi Bacteria Protists/Parasites 1. Viruses Flu HIV Measles Virus 2. Fungi Athlete’s Foot Candida albicans Fungus

3. Bacteria S STAPH Bacteria Strep throat 4. Protists Paramecium Giardia Giardia

The Immune System to g et h er to T h e i m m u n e sy st e m in cl u d es T c el ls a n d B c el ls. T h e c el ls w or k fi g ht in fe ct io n s. T The immune system includes T cells and B cells. he cells work together to fight pathogens and help destroy Cancer cells H How does the immune system work? Let’s find out!!

What happens when a virus infects a cell? What do T-cellsdo? What happens when a virus infects a cell? What do T-cells do?

What is another job of the T- cells?.

So, why do B – cells produce antibodies? Because……

ImmunityHow doesaperson becomeimmunized?How doesapersonbecomeimmunized?. ImmunityHow doesaperson becomeimmunized?How doesapersonbecomeimmunized?. Immunity How does a person become immunized?

How does the Immune System work T- cells recognize bacterial or viral antigen. Some T- cells attack cells infected with pathogens Other T-cells signal B cells to produce antibodies Other T-cells signal B cells to produce antibodies. Antibodies attach to the antigens on virus or bacteria Lock & Key) (Lock & Key) Antibodies help phagocytes destroy the bacteria or virus H o w d o e s t h e I m m u n e S y st e m w o r k H o w d o e s t h e I m m u n e S y st e m w o r k

Two Types of Immunity Active Immunity Immune system produces antibodies on its own in response to a pathogen Passive Immunity A ntibodies are injected into a patient to help prevent a disease from a pathogen Vaccine C ontains a weakened pathogen that stimulates production of antibodies without causing the actual disease, or…………? Antibodies are already in the vaccine

Active Immunity Both Passive Immunity The body makes antibodies. Memory cells recognize antigens from the pathogen from the pathogen. Immunity may last for years or a lifetime. Antibodies are given, the body does not make antibodies. Immunity can be acquired from the mother during pregnancy. Immunity lasts only a few months. Can prevent diseases May involve an injection

Review Questions 1. Question: What is the function of the immune system? Answer: Helps fight off pathogens. 2. Question: Which 3 white blood cells or lymphocytes help destroy pathogens? Answer: Macrophages, B cells and T cells 3. Question: What is an antigen? Answer: Special protein on surface of pathogens recognized by the immune system

4. Question: What is an antibody? Answer: Special protein in the immune system that recognizes and attaches to a specific antigen on a pathogen and marks the pathogen for destruction. 5.Q uestion: Explain the difference between Active and Passive Immunity? Answer: * In Active immunity the immune system produces the antibodies. * In Passive immunity the antibodies are injected into a patient to destroy the pathogens

Review Questions 6. Question: Which cells of the immune system produce antibodies? Answer: B cells 7. Question: Which cells produce B cells? Answer: T cells 8. Question: Name the 2 types of T- cells Answer: 1 1) Natural Killer cells 2) Cytotoxic cells 9. Question: What are memory T - cells? Answer: * They remember what type of antigens a pathogen has * Help immune system recognize the pathogen if it invades our body again!!

10. Question: What are the 4 main functions of T- cells Answer: * Stimulate B-cells to produce antibodies * Destroy pathogens after they are marked by antibodies * Destroy cells that are infected with a virus * Also recognize cancer cells and destroy them 11. Question: What are the 4 common pathogens? Answer: Virus Bacteria Fungi Protists/parasites :

12. Question: Name 2 ways a vaccine works! Answer: 1. Contains a weakened pathogen that stimulates production of antibodies without causing the actual disease, or…………? 2. Antibodies are already in the vaccine to destroy pathogens, body doesn’t need to make antibodies 13. Question: Why can’t scientists produce an effective vaccine against HIV? Answer: Because the virus mutates or changes and the vaccine no longer works!!!!!