Science defines human life as a characteristic that exhibit a process with organization, growth, adaptation, etc.; however, ancient sages told people human life is extremely valuable and sacred, as a religious doctrine in the Ten Commandments: “Thou shalt not kill.” Moreover, when people talk about ethics, they will think about rules to differentiate right and wrong. It might be wise maxims of Confucius or religious beliefs. The most general way to define “ethics” is that “moral principles that govern a person's or group's behavior” (American English in Oxford Dictionary). Bioethics is a pretty young interdisciplinary study, which is considered with ethical questions related to the relationships among human beings, animals, and environments in the late twentieth century. Based on this, bioethics derived three main subdisciplines, which are medical ethics, animal ethics, and environmental ethics. Although each sub-discipline has particular study area in bioethics, there still are overlaps of ethical considerations and approaches. This makes it difficult to easily discuss ethics questions such as stem cell research, xenotransplantation, the ethical status of animals and the ethical status of the environment. Further discussion about the vital issue of moral status solutions is necessary at the same time. In the rapid development of the natural sciences and biotechnology has greatly promoted better living conditions and improve the living standards of people around the world. On another hand, there are opposite consequences, like water and air pollution, nuclear waste, tropical deforestation, as well as large-scale livestock farming, as well as special innovative technologies, such as gene technology and cloning, resulting in doubts and even fears about the future of humanity. Blank legal system, for example, for abortion and euthanasia, many people are very concerned about another one of the reasons. Moreover, ethical issues, from specific conditions and dry, for example, genetic manipulation of food, they produce an intense public debate and serious public safety concerns and issues to consider in the past. As a discipline -specific approach applied ethics and moral reasoning depend largely on the findings in the life sciences, the main problem is that bioethics ethics, animal ethics and environmental ethics.
Medical ethics
The history of medical ethics can go back to the beginning of Hippocratic Oath, which is an ancient oath to restrain medical behaviors of physicians possibly in fourth century BC (Edelstein, L., 2000, p. 3). Medical ethics if not only limited to the Oath; after thousands of years’ developments, it has become to a complete system of moral principles that concern the values and judgments to the practice of medicine. As a result, this change has come out advances in medical fields and “affected nearly every aspect of clinical practice, from the confidentiality of patient records to end-of life issues” (Wells, K. R., 2007, p. 1528). For example, as Wells (2007) summarized, Dubler (2000) wrote an article including some topics of what he considered very important in medical ethics and “eHealth” is one on the list. “eHealth”, which means “The expansion of the Internet and other rapid changes in information technology have raised many questions about the confidentiality of electronic medical records as well as the impact of online education on medical training” (Wells, K. R., 2007, p. 1529).
According to Clouser (1997), medical ethics has roles. The first one is “a consciousness-raising enterprise, alerting us to everything from grossest injustice to subtlest nuance” (Clouser, K. D., 1997, p. 94). There is a well-known case called “Tarasoff v. Regents of the University of California” discussing the need to breach confidentiality in certain circumstances. The California Tarasoff case illustrates the difficulties in protecting patients’ confidentiality. In this case, a graduate student of UC Berkeley, Prosinjit Podder, went to university psychologist, Dr. Moore, talking about his intention of obtaining a gun and shooting a student called Tatiana Tarasoff. Then Dr. Moore faced a dilemma: protecting patient’s confidentiality, or protecting Tatiana Tarasoff from possible hurting. Dr. Moore chose to send a threat to campus police and they told Prosinjit Podder keeping distance to Tatiana. Mr. Podder convinced police that he was not dangerous to her; however, Mr. Podder later stalked and killed Tatiana after she travelling back. Tatiana’s parents sued the university for failure to warn Tatiana. After appealing, the California Supreme Court held that, “the discharge of this duty may require the therapist to take one or more of various steps. Thus, it may call for him to warn the intended victim, to notify the police, or to take whatever steps are reasonably necessary under the circumstances” (Supreme Court of California, 1976, para. 6). The implication of the California Supreme Court’s holding is that the third parties have legally restricts to access any medical records; however, doctors have duties to protect individuals from any credible hurting when they are aware of the harm.
The second role is “structuring the [medical] issues”, which means digging out the hidden principles and problems, then analyzing and solving them (Clouser, K. D., 1997, p. 95-96). One of the several involved elements could be inconsistent moral principle. For instance, when talking about human experiment, the Milgram Experiment of the Behavioral Study of Obedience is a noted one. Milgram tested human participants by questioning them with a shock punishment. The experiments were considered by some scientists to be unethical and physically or psychologically abusive. However, in another hand, this experiment does help scientists understanding the psychology of obeying authority.
Animal ethics In addition to medical ethics, animal ethics is another main issue of bioethics. It is basically concerned with the ethical problems of animal rights. It is an undisputed fact that animals inhabited the earth before human beings did. In fact, humans have been dependent on animals for thousands of years and animals paly a vital role in the society. However, with humans developing the way people treat animals is becoming increasingly cruel. Although animals are always seen as resources, the supply of food and clothing, there should be a moral obligation to treat animals decently. Current problems involved animal ethics includes animal testing, animal transporting, animal rights, etc. Among these problems, animal right is the most controversial one. When discuss the animal ethics issue, the first and probably more important factor is the ability to think and feel. While humans are complex developed beings who are able to feel emotions and think things; moreover, some other animals are also have the ability to feel pain or emotions. Hence non-human lives should also be considered having rights, such as healthy living places or enjoyable living conditions. Whereas humans are definitely more complex than any other beings, because of the abilities to talk and think, and to feel emotions specially. So it is possible that non-human lives deserve the “rights”, of course not as integrated as human beings’. Singer (1975) argued that all animals should have basic rights. He used the example of women movement to illustrate that people should be questionable if they required equal rights for women, blacks, and other human groups while denying equal rights for non-human lives. In addition to the ability of thinking and feeling, the similar generic structure is another considerable point. People know that since Origin of Species was published in nineteen century, humans are related with other animals. For this reason, it is people’s duty to give animal basic rights. We know that the difference between humans and gorillas is 0.01 %. Although, there is practically impossible to determinate how close we are to another animal as flies, sharks, and canaries. For this reason, scientists would use animal to do some experiments in remorselessly way. So people should analyze what are criteria for beings to have rights not to suffer, or be killed painfully.
Animal rights activists are working on reducing or even replacing the number of animals used in these experiments; or at least to reduce the pain of these poor creatures. Rats and mice makeup the majority of animals used in research. Rabbits, guinea pigs, hamsters, hogs, and cats, are other animals that are used for experimentation. Animal testing has been going on for great many years now, but even as technology advances we have yet to discover a replacement to laboratory animals. Some good things that come from animal testing are that a person is guaranteed that the product will be good and safe when they purchase it. A justification used is that it is better to hurt an animal versus killing them or possibly hurt human beings. According to the people who test experimental animals, which are not moral beings, so it is considered acceptable if they will be hurt during experiments, as long as it is not a human being that is being hurt. Most of what we know about medicine and our internal organs come from animal research. People against animal research believe that animals are moral beings like humans are and that they have the right to life. Just thinking about it every time people take medicine they are in a way taking part in an experiment, to see how the body will react to certain chemicals. Although it is hard for people to replace animals in equal places with humans, who are to say animals are or are not as morally important than human beings. As a conclusion, it will be very difficult to be completely fair treating animals as moral beings; however it is unfair to test them in cruel ways. They have always been a part of humans' everyday life, and no kind of new technology will ever place them. I believe that animal testing is 100% wrong because we are exposing innocent animals to harmful chemicals and harmful procedures. Also, animals are very moral creatures as humans, and they should be treated with more importance than now; because they are a component of the life cycle chain, and everything in the cycle is equally important.
Environmental ethics
Generally speaking, environmental ethics involves the moral problems in the relationship between human beings and any nature environment. It is not very commonly to put the words, "environmental" and "ethics", together; however, nowadays environmental ethics has become a prevalent subject in worldwide. Although environmental ethics does not have an exactly definition; however, Aldo Leopold is recognized as the father of the recent environmental ethics (Bazerman & Messick, p. 187). His Land Ethics, which means "ethic dealing with human's relation to land and to the animals and plants which grow upon it", has become the standard example of environmental ethics.
Environmental problems influence societies a lot. People are connected to everything in our world. People are connected thought all nature environment and resources in this world. For now, there is almost no global law to protect the environment and as a result, people need to be aware of the importance of environmental ethics. Most environment problems are caused by immoral organizations or individuals. For example, one of the biggest industrial disasters just was caused by immoral behaviors of Union Carbide company and its employees in Bhopal. It happened in December 3rd, 1984, water was mixed into highly toxic chemicals. More than half million people accessed the toxic chemicals and the chemical continuing impacted the nature environments in following years. The official immediate death toll was more than two thousands. However, after the disaster, almost million people were impacted by the poison. Environmental activists stated that the poison chemicals still existed in local landscape as well as water system. When people thinking about the issues that threaten the environment today, it is easy to feel the urgency of solving problems. One reason that the environmental problem is real serious because people have not realized the importance of environmental ethics. For years, people have exploited the world's resources without much thought about where that exploitation might be taking them. They have gone for the short-term gain and not considered the long-term picture. More cars, more clothes, more appliances, and more toys too often it is not a question of whether they need something but whether they want it. When a problem arises, no one wants to take responsibility for it. People need to learn how to take responsibility for their actions.
Humans have caused unmatched environmental changes. For example, the annual rate of global deforestation is nearly 1%, and in tropical rain forests alone (now less than 55% of their original cover), nearly 0.5% of all species are lost every year, an unprecedented rate (Brown, p. 227). Such changes may have devastating consequences for all life on earth and particularly human costs as well. In South Asia, West Africa, and other regions, drastic environmental changes contribute significantly, both directly and indirectly, to violent, civil conflicts and political and social instability. Less dramatic, but still essential, wetland, field, and forest habitats in the United States are being lost to development, and aquifers are polluted or depleted.
The concerns for environmental ethics might begin with thought of the Earth tomorrow. The Earth is a beautiful and unique place. It deserves to be preserved for its own goals and not just for what it can give to us. The government understands the importance of protecting the environment. In many cases, the government doesn't rely on individuals or organizations to do what's ethical when it comes to our environment. In 1970, the Environmental Protection Agency (EPA) was built to in response to public demand for cleaner water, air and land. The goal of the EPA is to protect the environment as well as human health.

Conclusion In conclusion, medical ethics, animal ethics, and environmental ethics are the three main issues of bioethics field. Although each issue has particular study area in bioethics, there still are overlaps of ethical considerations and approaches. In summary, bioethics is involved moral area of human conduct concerning the human beings and animals and lifeless nature in life sciences and handles the ethical problems, which come out from this complex subject. Furthermore, bioethics is an overlap disciplines field, at same time it also comes from various subjects. It is necessary to guide bioethics to people's general minds for valuing life itself and solving potential problems.