Question

To prevent a disease caused by a certain microbe doctors inject the same microbes in a person's blood. How is it ensured that this prevents the disease instead of causing it? What is this process of injecting microbes called ?

Answer 1

Answer: Injection of disarmed or weakened or dead pathogenic microbes in the body is called 'vaccination'.

Our body has a well developed immune system. Principle of vaccination is based on the property of 'memory' of immune system. The immune system produces antibodies against the microbes that were injected. Antibodies are proteins that are produced to destroy foreign microbes. These antibodies are not sufficient to kill the microbe, but since we had injected weak microbes hence we don't get harmed. Now in future when we actually get infected by that microbe, our body recognises it's previous encounter with that microbe and produces a massive army of antibodies against it and hence destroys it.

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Hope it helps!!