The Immune System

Louis Pasteur hypothesizes that disease is caused by small organisms. History of Medicine 1857 1883 1928 1955 Today Germ Theory Louis Pasteur hypothesizes that disease is caused by small organisms.

History of Medicine Koch’s Postulates Robert Koch finds 4 conditions that prove a pathogen causes a disease. 1857 1883 1928 1955 Today Germ Theory Louis Pasteur hypothesizes that disease is caused by small organisms.

History of Medicine Koch’s Postulates Robert Koch finds 4 conditions that prove a pathogen causes a disease. History of Medicine 1857 1883 1928 1955 Today Antibiotics Sir Alexander Fleming discovers penicillin. Germ Theory Louis Pasteur hypothesizes that disease is caused by small organisms.

History of Medicine Koch’s Postulates Robert Koch finds 4 conditions that prove a pathogen causes a disease. Polio Vaccine Jonas Salk’s vaccine against polio becomes available. Discontinued in the U.S. in 1994. 1857 1883 1928 1955 Today Polio Comeback! Worldwide efforts increase to vaccinate people against polio. Antibiotics Sir Alexander Fleming discovers penicillin. Germ Theory Louis Pasteur hypothesizes that disease is caused by small organisms.

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

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

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

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

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

Transmission How can pathogens be transferred? Indirect contact does NOT REQUIRE touching an infected individual. Touching an infected surface Breathing in infected air Drinking contaminated water Direct contact REQUIRES touching an infected individual. Kissing Hand shaking Sexual intercourse

Transmission Through Vectors Defined: organism that carries a pathogen Examples: Malaria – mosquitos carry the protozoan Black Death – carried by fleas of mice West Nile Virus – carried by birds, but spread by mosquitoes

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

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

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

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

White Blood Cells Job: Search & destroy Type 1: Phagocytes YouTube Clip: Types of White Blood Cells (phagocytes) from the BBC White Blood Cells YouTube Clip: Types of White Blood Cells (lymphocytes) from the BBC Job: Search & destroy Type 1: Phagocytes Surround & engulf invaders by phagocytosis Type 2: Lymphocytes T cells destroy infected cells B cells produce antibodies, which deactivate the pathogen.

phagocyte Blood stream bacteria phagocyte

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

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

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

Defense Proteins Interferon Cell becomes infected by virus Infected cell sends interferon to healthy neighbors Interferon causes healthy cell to create defense enzymes Healthy cell able to fight virus Virus RNA New virus New virus New virus New virus Interferon Interferon Interferon New virus Infected! Not Infected!

Immunity In all types of immunity, pathogens are destroyed before you get sick. Passive immunity occurs without an immune response. Mother’s milk Genetics Active immunity occurs after a specific immune response. Having chicken pox Acquired Immunity occurs after given a vaccine. Flu shot

Vaccination Prevents infections (not a cure) Vaccination process Weakened/dead pathogen or antibodies are 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

ReView Which part of our immune system coats the openings of the body? How do lymphocytes differ from phagocytes? What are antibodies and how do they help keep us from harm? What is the skin’s role in immunity? How can pathogens be transferred? Who hypothesized that disease is caused by small organisms? Which pathogen… Absorbs nutrients from living tissue? Are prokaryotic? What is the vector of malaria? What are the differences between passive, active, and acquired immunity? How do vaccines work?