Quote 2717

Faced with the onslaught of microbes, how does the normal human body defend itself and stay healthy? To begin with, it keeps out as many potential pathogens as possible with barriers such as the skin and other non-specific defences. The skin, which is waterproof, is impenetrable to most invaders, and it provides fatty acids that many microorganisms find toxic. Areas not covered by the skin, such as the eyes, mouth, lungs and digestive tract, are more vulnerable, but they have alternative defences. Tears, saliva, urine and other body secretions contain lysozyme, an enzyme that can kill certain types of bacteria by splitting the molecules found in their cell walls. Mucus in the nose and the airways engulfs bacteria and stops them penetrating the membranes. Cilia - tiny beating "hairs"- then push the mucus out of the airways into the throat, where it is swallowed. In the stomach, acid kills most of the microorganisms in food, as well as starting the process of digrestion.

Linda Gamlin

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Linda Gamlin Biology Creation Immune System

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