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The Immune System Protects The Human Body 3.1 Four Ways to Transmit Infectious Diseases Direct Contact – shaking hands, sharing a drinking container or exchanging saliva with someone. Indirect Contact – being near an infected person who sneezes without covering his or her mouth. Some pathogens can travel up to 5m. Water & Food – eating foods that are infected with bacteria. Animal Bites – i.e. rabies The Plague of the Mid 1300’s Dr. Lister Hey, what if we washed the tools? Dr. Lister Pathogens – disease causing invaders – bacteria or viruses. Invisible organisms. Lister’s hypothesis: what if germs were being passed to wounds from doctor’s hands and from medical equipment to patients. If medical equipment is sterilized to kill the pathogens then the death rate after surgery will be reduced First Line of Defense Second Line of Defence If a pathogen makes it past the first line of defence, the body has 2 types of immune responses: Innate and Acquired Second Line of Defence: Innate An innate response is quick, general, and non –specific. Any cell that enters your body that is not a nutrient and is not recognized as belonging to your body, is marked as an invader. These invaders include most bacteria and some viruses. Second Line of Defence: Innate The first action of the innate immune repsonse is a flow of fluid, cells from the blood (phagocytes) to the site of infection. This causes swelling, redness, fever, and pus. Second Line of Defence: Innate An increase of phagocytes Second Line of Defence: Innate http://www.bing.com/videos/search?q=phagocytes&mid=70E63146CAE 89E83D81E70E63146CAE89E83D81E&FORM=LKVR14# Second Line of Defence: Aquired This is a highly specific attack by a substance the body cannot recognize – from a virus to a splinter. The attacker can be a pathogen (disease causing organism) or an antigen (non living) Second Line of Defence: Acquired There are 2 types of Acquired Immune Responses: First Type: Second Line of Defense: Acquired http://www.brainpop.com/health/bodysystems/immunesystem/ http://www.teachersdomain.org/asset/tdc02_vid_immune/ A = Recognition - white blood cell surrounds pahtogen and signals T cells. More T cells are produced. Helper T cells signal B cells B = Mobilization - B cells produce antibodies C = Disposal - Antibodies destroy pathogens D = Immunity – Some antibodies remain for future use. Second Type: Second Line of Defense: Acquired – Killer T Cell Killer T Cells can work independently to destroy antigens or pathogens. Active Immunity Your body remembers which antibodies should be used to attack a pathogen that has infected it before. The Immune System Protects The Human Body 3.2 Mary Montagu Mary noticed people in Turkey in 1717 protecting their children from smallpox. They would scratch their children and place a drop of pus from someone who had a mild case of smallpox. Children would get blisters that would heal easily but would never get the full blown disease. Back in England she performed similar experiments on prisoners. This procedure eradicated smallpox from England. Unfortunately it was forgotten after her death. Mary Montagu Edward Jenner Edward Jenner was a doctor. He noticed that people who milked cows were immune to smallpox. These people previously had cowpox. Edward Jenner Edward Jenner’s Famous Experiment Jenner gave an 8 year old boy cowpox by placing him near infected cows. He then infected him with smallpox. He did not develop the disease. Vaccines A vaccine is a special version of an antigen that gives you immunity against a disease. A vaccine could be considered to be a weakened form of the disease. The vaccine stimulates your immune system to create antibodies against the disease. Disorders of the Immune System Allergies – an unusually high sensitivity to a substance. For example, if you are allergic to milk, milk acts as an antigen. Some common allergens include dander (dried saliva on skin flakes of cats), dust (feces of tiny dust mites) Allergens Histamines Histamines are a chemical that your body releases when you have an injury or need to fight invaders. Anaphylactic Shock Exposure to bee venom and peanuts can trigger a sever reaction called anaphylactic shock. Symptoms include swelling and difficulty breathing. AIDS Aids stands for Acquired Immunodeficiency Syndrome. AIDS infects the helper T cells. Body can no longer fight foreign pathogens. HIV is transfered in 2 body fluids – semen and blood.
