2. The Immune System

3. Pathogens Defined: microorganisms that cause disease – Viruses: turn cells into virus making factories

4. Pathogens Defined: microorganisms that cause disease – Viruses: turn cells into virus making factories – Bacteria: prokaryotes that can release toxic chemicals

5. Pathogens Defined: microorganisms that cause disease – Viruses: turn cells into virus making factories – Bacteria: prokaryotes that can release toxic chemicals – Fungi: pierce cells and absorb the nutrients

6. Pathogens Defined: microorganisms that cause disease – Viruses: turn cells into virus making factories – Bacteria: prokaryotes that can release toxic chemicals – Fungi: pierce cells and absorb the nutrients – Protozoans: single cells protista (eukaryotes) Plasmodium causes malaria

7. Pathogens Defined: microorganisms that cause disease – Viruses: turn cells into virus making factories – Bacteria: prokaryotes that can release toxic chemicals – Fungi: pierce cells and absorb the nutrients – Protozoans: single cells. Protists (eukaryotes) – Parasites: grow and feed on a host tapeworms

8. Transmission Some carried by wind, water, direct contact, indirect contact… Vectors: organism that carries a pathogen Examples: 1)Malaria – mosquitos carry the protozoan 2)Black Death – carried by fleas of mice 3)West Nile Virus – carried by birds, but spread by mosquitoes

9. The Skin 1 st line of defense: physical barrier Oils & sweat destroy some pathogens – Some pathogens burst…some shrivel Skin bacteria bacteria

10. Mucus Membranes Coat the openings of the body – Nose, mouth, ears, eyes, genitals, anus Lined with cilia & sticky fluids to trap pathogens

11. White Blood Cells Job: Search & destroy YouTube Clip: Types of White Blood Cells (phagocytes) from the BBC YouTube Clip: Types of White Blood Cells (lymphocytes) from the BBC

12. White Blood Cells Job: Search & destroy Type 1: Phagocytes – surround & engulf invaders by phagocytosis YouTube Clip: Types of White Blood Cells (phagocytes) from the BBC YouTube Clip: Types of White Blood Cells (lymphocytes) from the BBC

13. White Blood Cells Job: Search & destroy Type 1: Phagocytes – surround & engulf invaders by phagocytosis Type 2: Lymphocytes – create antibodies & destroy infected body cells YouTube Clip: Types of White Blood Cells (phagocytes) from the BBC YouTube Clip: Types of White Blood Cells (lymphocytes) from the BBC

14. Blood stream phagocyte bacteria phagocyte

15. Defense Proteins Antibodies – Created & released by lymphocytes – Attach to antigens (like handcuffs) lymphocyte antibody Y Y Y Y Y Y Y Y

16. Defense Proteins Antibodies – Created & released by lymphocytes – Attach to antigens (like handcuffs) How do they kill? 1)Causes pathogens to clump 2)Weakens the cell membrane of the pathogen

17. Y Y Y Y Y Y B CELLS MAKE ANTIBODIES ANTIBODIES ATTACH TO ANTIGENS OF THE PATHOGEN PHAGOCYTE DESTROYS PATHOGENS YY Y Y Y ANTIBODIES CAUSE THE PATHOGENS TO CLUMP TOGETHER Blood Stream Y Y Y Y Y YY Y Y Y Y Y phagocyte

18. Interferon 1)Cell becomes infected by virus 2)Infected cell sends interferon to healthy neighbors 3)Interferon causes healthy cell to create defense enzymes 4)Healthy cell able to fight virus Defense Proteins Virus RNA New virus Interferon virus Infected! Interferon New virus Not Infected!

19. Vaccination Prevents infections (not a cure) Vaccination process – Weakened pathogen is injected – Immune system produces… Antibodies to fight the weakened pathogen Memory cells for future infections Goal: Speed up immune response if you encounter the actual virus

20. Review 1)Which part of our immune system coats the openings of the body? 2)How do lymphocytes differ from phagocytes? 3)What are antibodies and how do they help keep us from harm? 4)Which pathogen… absorbs nutrients from living tissue? are prokaryotic? 5)Which illness is spread by mice? 6)What is the vector of malaria?