This is a sequence of animations broken into five parts on the topic of Selye's General Adaptation Syndrome.
  1. Part 1 of 5:
  2. The on-screen text says "Concern about the physical effects of stress was first voiced by Hans Selye, a Canadian scientist who coined the term stress many decades ago. Selye formulated an influential model of stress reactions called the general adaptation syndrome. According to his model, the body’s response to stress may move through three stages: alarm, resistance, and exhaustion."
  3. Part 2 of 5:
  4. The on-screen text says "In the first stage, an alarm reaction occurs when an organism first recognizes the existence of a threat: Physiological arousal occurs as the body musters its resources to combat the challenge. Selye’s alarm reaction is essentially the fight-or-flight response, which involves intense arousal."
  5. Part 3 of 5:
  6. The on-screen text says "However, Selye took his investigation of stress a few steps further by exposing laboratory animals to prolonged stress, similar to the chronic stress often endured by humans. As stress continues, the organism may progress to the stage of resistance, during which physiological changes stabilize. Arousal continues to be higher than normal, although it may level off somewhat."
  7. Part 4 of 5:
  8. The on-screen text says "If the stress continues over a substantial period of time, the organism may reach the stage of exhaustion. Selye believed that the body’s resources for fighting stress are limited. If the stress can’t be overcome, the body’s resources may be depleted. Eventually, he thought, the organism would experience hormonal exhaustion, leading to what he called diseases of adaptation."
  9. Part 5 of 5:
  10. The on-screen text says "Selye’s insight that stress can have harmful effects on physical health has held up, but we now know that such outcomes are not due to hormonal exhaustion. The crux of the problem is that chronic overactivation of the stress response can have damaging physiological effects on a variety of organ systems and undermine immune functioning."