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 Every day your body is exposed to many pathogens.  Your body can trap, repel or destroy may of these intruders.  Most of these pathogens enter the.

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Presentation on theme: " Every day your body is exposed to many pathogens.  Your body can trap, repel or destroy may of these intruders.  Most of these pathogens enter the."— Presentation transcript:

1  Every day your body is exposed to many pathogens.  Your body can trap, repel or destroy may of these intruders.  Most of these pathogens enter the body through the eyes, nose, mouth and skin.

2  Tears-wash away pathogens. They also contain chemicals that kill some harmful organisms.  Saliva-destroys may harmful organisms in your mouth.  Skin-acts as a protective barrier, but pathogens can enter through cuts, burns, or scrapes.

3  Mucous membranes-tissues lining the mouth, nose, throat, eyes and other body openings, trapping the pathogens. ◦ You expel many of the pathogens that your mucous membranes catch when you sneeze or cough.  Stomach acid-destroys many pathogens.

4  Immune system-a combination of body defenses made up of cells, tissues and organs that fight off pathogens. ◦ The immune system snaps into action when a pathogen breaks through one of the five barriers.

5  When pathogens enter the body the immune system launches an attack.  The inflammatory response occurs if a foreign invader gets past the five barriers.  This attack occurs in the blood and tissues. ◦ The blood supply to the area increases. ◦ Raises the blood pressure in area causing fluid to leak from the blood vessels, causing surrounding tissues to swell. (inflammation) ◦ White blood cells called phagocytes attack the invaders by surrounding them and eating them.

6 ◦ The phagocytes release special proteins to defend the body.  Interferon-is a protein that stops viruses from reproducing and helps the cells the fight infection.  If the infection has spread throughout the body a fever starts which signals the body to produce more white blood cells, making it difficult for some pathogens to reproduce.

7  What happens when pathogens are able to survive the inflammatory response? ◦ The body counters with a specific response tailored to a particular pathogen and the poisons it produces.  This not only defends the body from the invading pathogen, but allows the immune system to remember the type of pathogen.  This allows the pathogen to be destroyed more quickly if the body encounters it again.

8  Lymphatic system-a secondary circulatory system that helps the body fight pathogens and maintain its fluid balance. ◦ The lymphatic system circulates a watery fluid known as lymph. ◦ The lymph contain phagocytes called macrophages that digest and process invading pathogens, helping the lymphocytes identify them. ◦ Lymphocytes-are special white blood cells found in the lymph.

9  There are three types of lymphocytes, which are important for fighting off pathogens and disease.  B cells-formed in bone marrow.  T cells-developed in the thymus gland.  NK cells-natural killer cell, attacks cancerous growths.

10  Antigens-substances that send the immune system into action.  Antibodies-proteins that attach to antigens, keeping them from harming the body.  Go over 12.4 pg. 339

11  Immunity-the body’s ability to resist the pathogens that cause a particular disease. ◦ You are born with some immunity passed from your mom. ◦ Your body builds up immunity by being exposed to pathogens and having certain diseases by producing memory B and T cells. ◦ Vaccine-a preparation of dead or weakened pathogens injected into the body to cause the immune system to produce antibodies.

12  Immunization-process or getting vaccinated because the antibodies your body produces will build immunity. ◦ Since the pathogens are dead or weakened the vaccination will not cause you to get sick. ◦ Vaccines have been developed for many diseases including:  Polio  Measles  Mumps


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