Sentence:  In one sense the role is not new. The lay family member who attends the sick relative is part of a more ancient tradition than the physician or nurse. What is new in the concept of the <WSD>responsor</WSD> is contributed by the increasing complexity of modern therapy for chronic illness and the slow development of organized home care as a formal system for the application of such therapy in private  homes. 
Meaning of the word marked with <WSD> tags:  A person who is assigned responsibility for daily care of a person with a chronic illness and for working with the health care professionals.