To be blunt the answer is both, but to different degrees. Everybody has a pre-ordained response to stress on a purely physical level. When we are put into a stressful situation are body goes through a whole host of changes that aid in dealing with stress, or rather physical stress. The so called flight or fight response is useful when you suddenly need a lot of energy but if you are at work and this response activates you have no need of sudden energy. This then becomes a problem when the stress becomes chronic.
The pioneer of stress research was Selye. In 1936 he conducted experiments on rats attempting to discover a new sex hormone….(short extract)