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

Types of Lymphocytes T cells - Identify Pathogens by recognizing their Antigens B cells - Produce chemicals called Antibodies Macrophages – Surround pathogen and digest or eat it Also called Phagocytes Pathogens

WWWWhat are Memory Cells ? Remember what type of antigens a pathogen has Help immune system recognize the pathogen if it invades our body again!! AMAZING ! ! ! WWWWhat are the 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

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

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

4 TYPES OF COMMON PATHOGENS  C C C 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

4 TYPES OF COMMON PATHOGENS 4 TYPES OF COMMON PATHOGENS 3. Bacteria STAPH Bacteria Strep throat 4. Protists Paramecium Giardia Giardia

The Immune System 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 infections. How does the immune system work? Let’s find out!!

T-Cells have more than one job One job may be to…………… What happens when a virus infects a cell? T-Cells have more than one job One job may be to…………… What happens when a virus infects a cell?

What is another job of the T- cells?.

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

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

How does the Immune System work 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. Antibodies attach to the antigens on virus or bacteria (Lock & Key) Antibodies help macrophages 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 Two Types of Immunity Active Immunity Immune system produces antibodies on its own in response to a pathogen Passive Immunity Antibodies are injected into a patient to help prevent a disease from a pathogen Vaccine Contain 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 Active Immunity Both Passive Immunity The body makes antibodies. Memory cells recognize antigens 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

Review Questions 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 it for destruction. 5. Question: 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: What are memory cells? Answer: Remember what type of antigens a pathogen has Help immune system recognize the pathogen if it invades our body again!! Help immune system recognize the pathogen if it invades our body again!!

9. Questions: What are the 4 main functions of T-cells Answer: 1. Destroy pathogens after they are marked by 1. Destroy pathogens after they are marked by Antibodies Antibodies 2. Destroy cells that are infected with a virus 2. Destroy cells that are infected with a virus 3. Also recognize cancer cells and destroy them 3. Also recognize cancer cells and destroy them 4. Stimulate B-cells to produce antibodies 4. Stimulate B-cells to produce antibodies 10. Question: What are the 4 common pathogens? Answer: Virus Bacteria Fungi Protists/parasites