| Selye (1956) wrote "stress is the non specific (physiological)
response of the body to any demand made upon it" ie. a response
to the demands of the environment. He described a universal stress response
which serves both to protect the organism and to preserve its integrity.
The response progresses, with continual or repeated exposure to the stressor,
through three identifiable stages. During the first stage the body shows
an alarm reaction through the changes in physiology described above and
mediated by the hypothalamus and pituitary gland. At the same time, however,
the level of resistance is reduced and if the stressor is severe enough,
homeostasis may collapse altogether resulting in the death of the individual.
The second stage of the syndrome is resistance. The bodily changes characteristic of the alarm reaction disappear and are replaced by changes marking the organisms adaptation to the situation. Resistance rises above normal due to prolonged high levels of adrenaline. The final stage is one of exhaustion. Following long term exposure to
the same stressor, or the addition of a further stressor, the necessary
energy to adapt is exhausted. Signs of the alarm reaction reappear, and
collapse results which may be fatal. See Fig 8
Selye's argument was compiled when a medical student. He noted a general malaise with being ill, irrespective of the specific nature of the illness, characterised by loss of appetite, an associative loss of weight. strength and ambition together with an associated facial expression. Further examination of extreme cases and experimental animals revealed enlargement and dark discolouration of the adrenals. intense shrinkage of the thymus, spleen and lymph nodes and deep bleeding ulcers of the stomach and upper gut. Selye believed this syndrome of sickness was imposed on all diseases. It appears however, that he overstated the case since Mason (1971) noted that exercise, fasting and heat do not produce the syndrome. Further, the response is different if the organism perceives the stressor as grounds for anger - since there is positive evidence to suggest that anxiety is associated with the release of adrenaline and anger with the release of noradrenaline. Link to previous page | next page | SAQs part two | index |
