Life processes are similar in all animal with backbones. So physiologists can find out a lot about the human body by studying animals such as frogs, rats and rabbits. Sometime research involves the death of these animals. But physiologists take great care not to hurt the animals. The animals are usually put to sleep during the experiments so they do not feel pain. Many people think animals should not be used for experiment. But it is only by physiological research that medicine has been able to advance.