Many people do not take enough care of their complex machines. Bad habits like smoking, drinking too much alcohol, and eating junk food damage our bodies. Stress can also cause health problems. People who worry a lot or have busy jobs often don’t get enough sleep, or don;t eat properly. We also damage our bodies by playing sports or having accidents.In 1999, Americans made more than 102000000 visits to emergency rooms. The two most common reaons were for injury and poisoning. ER patients were also treated for many other medical problems -from bad cuts and broken bones to serious illnesses that needed surgery.