Fighting Disease

Pathogen An organism that causes diseases All infectious diseases are caused by pathogens When you have an infectious disease a pathogens have gotten inside your body and caused harm

4 major pathogens 1. Bacteria-damage cells by producing a toxin (tetanus, strep throat) 2. Viruses- destroy cells as they reproduce inside (flu, colds) 3. Fungi- athletes foot, ringworm 4. Protists- malaria, African Sleeping Sickness, dysentery.

Spread of Pathogens -Infected people- directly (kissing) or indirectly (sneezing, coughing) -Soil, food, water- contagen in the food, soil, or water -Contaminated object- indirect contact -Infected animals- ticks, mosquitoes, raccoons, etc (biting a person)

The Body’s Defenses Skin is first line of defense Breathing passages have cilia Mouth and stomach have chemicals to destroy pathogens

Immune system response White blood cells- phagocyte (engulfs pathogen) Inflammation- Increases blood flow to infected area (white blood cells) Fever- Pathogens can’t grow at higher temperatures TCells- distinguishes one pathogen from another

Immune system cont.. B Cells- Produce proteins that help destroy pathogens (antibody) Antibodies bind to the pathogen and stop it from making you sick

AIDS Caused by the virus HIV Attacks T cells and shuts down the immune system Body loses ability to fight disease Spread by body fluids- not shaking hands, hugging, toilet seat etc…

Immunity Active- bodies response to presence of pathogens. - result of getting the disease or a vaccine Passive- Antibodies come from another source other than body (immunity passed from mother to baby at birth)

Cancer Non-infectious Cells multiply uncontrollably Carcinogen- cancer causing agent (tar in cigarette, uv radiation in sunlight)

Vaccination Antibodies and memory cells form When real pathogen enters the body the memory cells help produce antibodies to fight it

Antibiotic Slows growth or kills bacteria Totally ineffective against viruses

Vector Carries the disease but does not actually have the disease (ticks, mosquitoes)

Carrier Has the disease but shows no sign of the disease (some people carry strep throat but never have any symptoms) Are still contagious even without symptoms