A person's body is like a machine . it has many parts that help keep it running . if these parts are running well , a person will be healthy . but sometimes a person's body breaks down . then that person get sick . many times , germs make a person sick. when germs attack a body , it needs to fight back . the person's body alone can defeat the germs . other times , the person might need medicine from a doctor to get better . fortunately , many medicines can kill germs and help bodies become healthy again!