Explain How The Body Defend Itself Against Infection

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A&A2- How the body defends itself against infection An infectious disease is caused by pathogens. Many pathogens do not cause harm as the human body has physical, chemical and cellular defences that prevent these pathogens from entering the body. If pathogens do enter, then the immune system can prevent them from spreading through the body. The immune system is involved in the recognition and rejection of foreign cells and tissues. Most of the white blood cells of the immune system recognise a foreign cell or virus as something that does not belong to the body, because that foreign cell or virus does not have the correct antigen. When the white blood cells of the immune system identify the foreign cell or virus, they respond by attacking the invader.…show more content…
Non-Specific Immune Response Non-specific immune responses are present at birth; they prevent microbes from entering the body by physical, chemical and cellular means. It offers a quick response system which is effective against a wide range of pathogens and foreign substances. This system does not distinguish between the different pathogens and it always gives the same response. The non-specific immune response is further divided into; 1. The first line of defence- The skin, mucous membranes and their secretions The skin provides both a physical barrier to invasion by pathogens and a chemical barrier (due to sweat). In addition to the skin, three other potential routes of entry by microorganisms must be guarded: the digestive tract, the respiratory tract and the urogenital tract. These are guarded by; • Tears, nasal mucus and saliva – these contain lysozyme • Mucus- physically traps microbes • Cilia- sweep up the mucus and microbes which are then either coughed, sneezed or swallowed • The intestines are inhibited by bacteria that are harmless to the human body but secrete substances that destroy invading foreign bacteria and

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