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