ZIMSEC O Level Combined Science Notes: Disease:The body’s defence mechanisms
- The body is equipped to deal with and defend itself against diseases and infections
- These defends, while inadequate, are effective and essential
- Skin-is a physical barrier against all bacteria and other pathogens
- Wax and hairs-found in the ears prevent invasion by microorganisms
- Mucus and hairs-found in the nose trap invading bacteria and spores
- Stomach acids-they kill bacteria in the food
- White blood cells-some of them engulf and digest bacteria while others produce antibodies to destroy bacteria/neutralise toxins/poisons produced by bacteria
- Tears-have a mild antiseptic to kill bacteria in the eyes
- Blood clotting-is caused by platelets in the blood at damaged parts of the skin. This involves blood proteins in the plasma forming a network of fibres and eventually clotting. Clotting also helps prevent loss of blood.
- Saliva-it has a cleansing action
To access more topics go to the Combined Science Notes page
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