Stress is the condition that results when person-environment transactions lead the individual to perceive a discrepancy, whether real or not, between the demands of a situation and the resources of the person's biological, psychological or social systems. In medical terms, stress is the disruption of homeostasis through physical or psychological stimuli. Stressful stimuli can be mental, physiological, anatomical or physical reactions. The term 'stress' in this context was coined by Austro-Canadian endocrinologist Hans Selye, who defined the General Adaptation Syndrome or GAS paradigm in 1936.