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First Line of Defense Skin Salivia Stomach Acid Sweat Nose Tears Hairs & Mucous First line – FAILED A Pathogen - something foreign to the body Was let in. What would be an example of a pathogen? Second Line of Defense macrophages - biggest white blood cell (W.B.C.) -Know a pathogen by its marker proteins - eat pathogens -Part of the destroyed pathogen is placed on their membrane Like a victory banner 3rd Line of Defense Macrophage tells Helper T-cells the pathogen’s marker proteins (remember the Victory Banner?). T-cells make a hormone (a message) that tells… -B-cells to make antibodies -Killer T-cells to divide B cells produce antibodies that circulate in the blood & lymph streams Antibodies Mark pathogens Antibodies are specific (made to mark only a certain kind of pathogen) Killer T-cells - kill infected cells - kill pathogens with antibodies (The Killer T- cell is marked by the arrow. It is killing a much larger influenza virus infected target) Suppressor T-cell Stops the B-cells from making antibodies. B-cells leave behind memory cells that watch for the pathogen. If they find one, they start multiplying to kill it. This process is so immediate & explosive that the pathogen is killed before you know you are sick. Memory cells make you immune to that pathogen Second Introduction First Introduction Time Allergies – an abnormal response to a pathogen (pollen, dust, pets etc.) Immune system is super-sensitive to the pathogen and starts the first line of defense. Viruses are made up of a protein & RNA or DNA It is debated whether viruses are living or non-living things since they cannot reproduce on their own. 1. Viruses inject their DNA/RNA into our cells 2. Our cells produce the viruses 3. Our cell dies To combat a virus we use vaccines. Vaccines (virus) - help our body to produce memory cells Retro viruses (HIV) - change their protein, so our memory cells do not recognize them. Bacteria are living things (Monera) unlike viruses Good Bacteria -make yogurt, -treat water - clean oil spills etc. Antibiotics kill bacteria by damaging their cell wall Our cells do not have cell walls So, antibiotics do not hurt our cells