Q1.
You would have noticed that some people get sick more frequently than others, although living in a similar environment. Do you know why?
Answer
Because they differ in immunity — the natural ability of the body to fight diseases. The work is done by a special system called the immune system.
Two people can breathe the same air and drink the same water, and still fall ill differently, because the immune system is not equally strong or equally prepared in both:
- Previous exposure. Someone who has already met that pathogen — or been vaccinated against it — has acquired immunity and fights it off before it can cause illness.
- Age. Very young children and elderly people have weaker defences.
- Nutrition. A balanced diet is what the immune system is built from; a body short of nutrients cannot maintain it.
- Sleep, exercise and stress. These decide how well the body repairs itself, as Activity 3.1 showed.
- An existing illness. A person already living with a chronic disease has less in reserve to spend on a new infection.
Why it happens: falling ill is not decided by the pathogen alone. It is the result of a contest — the number of pathogens that get in, against the strength of the immune system that meets them. Change either side and the outcome changes.