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October 13, 2009 Your body has many ways of fighting diseasecausing bacteria, viruses, and other pathogens. Skin Mucous Membranes Chemicals Your body also has separate defense systems like the inflammatory response and the immune system. Your bodies first line of defense helps keep many pathogens out of the body. Your skin is part of the physical barriers that block out pathogens. Your skin uses chemicals, such as sweat and oil, to kill pathogens that settle on your body. Your skin is always nonstop repairing itself so pathogens cannot get through (cuts). Soft tissues that line the nose, mouth, throat, digestive tract, etc. Make slimy material known as mucus Pathogens get caught in the mucus lining while air is carried to lungs. -Trap pathogens Cilia- tiny, hair-like structures that line tubes in body. Move mucus to back of throat, then by swallowing, pathogens are sent to the stomach where they are destroyed. Many chemicals in your body destroy pathogens. Sweat is acidic, and it inhibits the growth of bacteria. Your stomach secretes acids that not only help digest food but they also help kill bacteria. Tears contain protein that kill bacteria. Sometimes pathogens cross protective barriers (skin and mucous membranes). Inflammation is the second way your body protects itself. Inflammation- a reaction to injury or infection that is characterized by pain, redness, and swelling. When protective barriers are broken and part of your body becomes infected, the area becomes inflamed (gets hot). Blood vessels expand; more blood to the injured area. Pus- yellowish substance that build up around injury. -Dead or injured body cells that were fighting bacteria and dead and injured bacteria. Made up of certain types of blood cells and proteins called antibodies. Lymphatic system- a network of vessels that carry lymph throughout the body. Picks up fluid from all over the body and sweeps up bacteria and viruses and carries them to the lymph nodes. Lymph nodes are filled with white blood cells. White blood cells- cells in the blood whose primary job is to defend the body against disease. Some WBCs produce antibodies that bind to pathogens and warn other WBCs to destroy the pathogen. Swelling lymph nodes= increase in WBCs to fight off infection. System’s defense takes time to defeat pathogens and disease. Cells of your immune system work to fight a specific pathogen, as opposed to your bodies other defense (skin, mucous membranes, etc.)