Why do people fall ill?

The human body is made up of many
organs and systems. The organs include
the brain and the heart, the liver, the lungs
and the kidneys. If even one of these organs
does not do the work it is supposed to
do, we can fall ill. To work well, the body
needs the right kind of food in the right
quantities. It also needs exercise and a
clean environment. Any imbalance in
these factors can cause us to fall ill.