What keeps us from getting sick? Our immune system is the body system that protects the body from infection and disease. Vocabulary: Antibody Antigen Immune system Pathogen White blood cells (c) McGraw Hill Ryerson 2007

The Immune System Infectious diseases are caused by pathogens. A pathogen is a microorganism that invades the body and cause disease. Eg. Salmonella can cause food poisoning When a pathogen enters the body, it causes an immune response. The immune response is the immune system mounting an attack to destroy these disease-causing invaders. See pages 100 - 101 (c) McGraw Hill Ryerson 2007

How do pathogens enter our bodies? 1. Direct Contact (through breaks in the skin) Pathogens can enter the body from body fluids such as saliva, blood and semen, through cuts and scratches, and through needle punctures. Kissing, touching, sexual intercourse Eg. Sexually transmitted diseases, hepatitis, and HIV/AIDS are often spread by this route. (c) McGraw Hill Ryerson 2007

How do pathogens enter the body? 2. Indirect contact (Inhalation) When you cough or sneeze, tiny droplets fly out of your mouth and nose. If you have an infection, those droplets will contain microorganisms. Other people can breathe in the droplets, along with the viruses and bacteria they contain. The common cold and tuberculosis are spread in this way  COUGH INTO YOUR SLEEVE! (c) McGraw Hill Ryerson 2007

How do pathogens enter our bodies? 3. By Ingestion (through the mouth) Consuming food or water contaminated with bacteria or viruses Improperly cooked food may contain Salmonella  or  E. coli. Water needs to be purified by filtering, chemicals, or boiling. (c) McGraw Hill Ryerson 2007

How do pathogens enter the body? 4. By vectors (usually through the skin or by ingestion) A vector is an organism that doesn’t cause disease but spreads it from one host to another without suffering any harm itself. Vectors include mosquitoes (malaria and Zika virus) and houseflies (dysentery). Bites from an animal with rabies virus. (c) McGraw Hill Ryerson 2007

Ted ed germ theory https://www.youtube.com/watch?v=N9LC-3ZKiok How are germs spread? The Sneeze https://www.youtube.com/watch?v=yToii3-p-NI Ted ed germ theory https://www.youtube.com/watch?v=N9LC-3ZKiok  Ted ed How germs spread https://www.youtube.com/watch?v=yxonJTWhBJQ (c) McGraw Hill Ryerson 2007

Activity: Pass it on. Spread your germs (c) McGraw Hill Ryerson 2007