Protecting your body from all invaders every second of every day THE IMMUNE SYSTEM Protecting your body from all invaders every second of every day Immune System: Body’s primary defense against disease-causing microorganisms.

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ON THE DEFENSE Pathogens: These enemies are foreign bodies that enter your body and can cause disease. They could be viruses or bacteria

Prokaryotic microorganisms Present in most habitats on earth Bacteria Prokaryotic microorganisms Present in most habitats on earth Virus Infectious agent that replicates inside the living cells of an organism

HOW DO YOU COME IN CONTACT WITH PATHOGENS EVERY DAY? THINK PAIR SHARE HOW DO YOU COME IN CONTACT WITH PATHOGENS EVERY DAY?

HOW COULD YOU LIVE IF YOU HAD NO IMMUNE SYSTEM?

https://www.youtube.com/watch?v=LVKqV7a31Rs

FIRST LINE OF DEFENCE The first line of defense blocks a large percent of the pathogens that want to invade our bodies. Our skin: The dead outer layer of the skin, known as the epidermis, provides a physical barrier. It acts much like the wall protecting a castle from invaders.

FIRST LINE OF DEFENCE The sweat and oil on our skin These provide a slightly acidic environment and prevents some pathogens from growing on our body and skin.

FIRST LINE OF DEFENCE Gastric juices in our stomach Also provide a slightly acidic environment. This helps to kill some pathogens that we eat.

FIRST LINE OF DEFENCE Mucus in our nose and respiratory system. As you breathe in, foreign particles and bacteria bump into mucus throughout your respiratory system and become stuck

SECOND LINE OF DEFENCE While the first lines of defense work to keep out a majority of invaders, some sneaky ninja pathogens make it through undetected. This is called an immune response and the job of the super-heroes is to destroy the pathogens.

SECOND LINE OF DEFENCE There are two types of immune responses: Innate immune response Acquired immune response

INNATE IMMUNE RESPONSE General and non-specific Very fast acting Its first action is inflammation Swelling, fever, and redness in one area Phagocytes are released (first superhero) White blood cells patrol the body searching for pathogens and EAT them phagocyte breaks the foreign particles apart in organelles called lysosomes http://www.youtube.com/watch?v=qvGVoxdy-yM

AQUIRED IMMUNE SYSTEM Highly specific attack on a particular pathogen or antigen. Antigen: Any nonliving substance the body cannot recognize (anything from virus to a sliver) Can take a week to develop Gives you active immunity Your body remembers the specific antigen and develops antibodies against the antigen

AQUIRED IMMUNE SYSTEM B cells Warning System: Recognize antigens in the body Produce antibodies to fight antigens Antibodies: cover antigen Prevent antigen from infecting body cells Mark it for destruction by white blood cells

AQUIRED IMMUNE SYSTEM Killer T cells Work alone and destroy antigens Helper T cells Roam the body searching for invaders When invaders are found, T cells signal B cells to start immune response

Cell before infection… Viruses Viruses enter body cells, hijack their organelles, and turn the cell into a virus making-factory. The cell will eventually burst, releasing thousands of viruses to infect new cells. …and after. Cell before infection…

What happens to already infected cells? Interferons Virus-infected body cells release interferon when an invasion occurs Interferon – chemical that interferes with the ability to viruses to attack other body cells What happens to already infected cells?

Vaccines Polio 1952 60,000 cases in the US 3000 fatalities 1955 Salk vaccine 1979 eliminated in US Polio – virtually eradicated from western hemisphere. Horrible from in US from 1900 -1955 when the Salk vaccine was widely made available The height of the epidemic was 1952 60,000 cases 3000 fatalities 5% fatality rate. Typically transmitted in poop (not washing hands or drinking contaminated water)

How do vaccines work? Vaccines are made up of weakened viral particles. The weakened particles stimulate a Primary Immune Response – body recognizes agent as foreign, destroys it and remembers it, so next time it can recognize and destroy the virus right away When the pathogen actually attacks, the Secondary Immune Response occurs. memory cells divide and produce large numbers of antibodies, are produced stopping the infection before you can become sick 23