Image credit keyword-suggestions.com

Image credit keyword-suggestions.com

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
Some of the body's defenses. Image credit schoolbag.info

Some of the body’s defenses. Image credit schoolbag.info

  • 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


Quick NetOne, Telecel, Africom, And Econet Airtime Recharge

If anything goes wrong, chat with us using the chat feature at the bottom right of this screen