We know that most of the diseases are caused by pathogens. How do we fight against these foreign bodies?Our body has two defence mechanism:
non-specific (local) defence : blocks the entry of pathogens or destroys the pathogens. This defence maybe external(e.g. skin, mucus membrane) or internal (e.g. WBC).
Specific defence: This type of defence is brought by immune system.For defending the organisms immunity has to be developed.
Types of immunity-
innate i.e. inborn
acquired immunity - acquired during lifetime. Types of acquired immunity are Active immunity and passive immunity.
Vaccination: Artificially immunity can be acquired by taking vaccination. e.g. polio, measles vaccine Antibiotics: It is a chemical substance produced by a micro-organism which inhibits or kills another organism. e.g. Penicillin