Answer:
Nursing is both a science and an art. Its purpose is to provide care, to improve the health of individuals and also of populations, both through the practice of interventions and its art in general, and also through the acquirement of knowledge that backs those interventions. Although Nursing has now developed its own scientific basis, it cannot be denied that a lot of those scientific principles have been born from the acquirement of knowledge from other sciences, and disciplines.
Nursing is not a field of healthcare that can stand on its own. First, a lot of its knowledge has been acquired from sciences such as biology, chemistry, and most of all, medicine. Borrowing from these fields does not demerit the fact that today Nursing has its own scientific knowledge, developed from Nursing practice and from experience and application of scientific principles. But this would not have been possible without borrowing from other fields of study, and especially, those related to healthcare.
An example of this is the appliance of Nursing procedures, like position changes, counseling in different health topics, or the administration of pharmaceutical products. These processes, which are part of a nurse´s activities, first developed from the knowledge that nurses acquired while also sharing the practice of other professionals, and through coming in contact with the knowledge produced by other fields of study. Now, after years of applying this borrowed knowledge, Nursing has made it its own, and theories of Nursing are now independent, but they also still interrelate with other fields of study. It is called teamwork, and its purpose is to benefit a patient.
So, essentially, I think that it is wrong to think that Nursing should not borrow theories from other disciplines. Healthcare professionals work as a team, and there are a lot of grounds on which each discipline meets and they can all benefit from "borrowing" knowledge and practice from one another.