The Immune System Protecting the Body

First Line of Defence The skin keeps out bacteria and viruses The skin keeps out bacteria and viruses Acidic oils and sweat prevent micro-organisms from growing on the skin Acidic oils and sweat prevent micro-organisms from growing on the skin

Eyes: have tears with a special chemical to kill bacteria Eyes: have tears with a special chemical to kill bacteria Ears: have wax to trap foreign material Ears: have wax to trap foreign material Mouth and Nose: have mucus to trap micro- organisms Mouth and Nose: have mucus to trap micro- organisms Cilia in the trachea move the mucus with the invaders out Cilia in the trachea move the mucus with the invaders out

Second Line of Defence The circulatory system The circulatory system White blood cells attack and destroy invaders in the blood stream White blood cells attack and destroy invaders in the blood stream Video of white blood cell attacking a bacterium Video of white blood cell attacking a bacterium Video of white blood cell attacking a bacterium Video of white blood cell attacking a bacterium

Third Line of Defence The immune system The immune system All invaders have markers called antigens on their surfaces All invaders have markers called antigens on their surfaces Special white blood cells make antibodies to attack them Special white blood cells make antibodies to attack them Each type of antibody only recognizes one type of antigen Each type of antibody only recognizes one type of antigen

Immune Response This is when antibodies are used to fight pathogens This is when antibodies are used to fight pathogens The body can produce its own antibodies or they can be induced through vaccinations to help fight against future attack by the same pathogen The body can produce its own antibodies or they can be induced through vaccinations to help fight against future attack by the same pathogen