Wikis > Microbiology and Infection Control > Defence against infection > Mechanical barriers / “First line of defence”
Mechanical barriers / “First line of defence”
Skin:
• physical and mechanical barrier to organisms – they can gain entrance if cut, abraded or burnt.
• secretions (perspiration and fatty acids) bacteriocidal due to acidity (pH of 3-5); sebum also has chemical toxic to bacteria
• normal flora
• muscous membrane provides continuous barrier
Respiratory system:
• mucous membrane – contains phagocytes
• cilia traps dust and microbes swallowed or expelled (cough)
• lysozymes – in nasal secretions, , saliva and tears
Digestive system:
• acidity of stomach and alkalinity of intestines
• secretes protein digesting enzymes
• bath bactericidal and bacteriostatic
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