Psychology WJEC PY1 Biological Theory

Exam question 1(a) "Describe Selye's General Adaptation Syndrome as an explanation of stress." [8]

Structure your answer clearly like this:

Briefly describe stress and link the theory to the correct assumption. (e.g. The Endocrine System)

Introduce Hans Selye and his theory developed in 1956. Key points to mention here are:

• Response is universal
• Stress hormones released
• fight or flight mode
• stress is 'the individuals physiological response, mediated largely by the autonomic nervous system and the endocrine system to any demands made on the individual'
• Three stages of GAS

Now you must list and describe each of the stages of the GAS model in order. e.g.

• Alarm Stage - description including these important points (Autonomic Nervous System, Adrenaline, Fight or Flight, Shock Phase and Counter Shock, Hypothalamus - signals ANS)
• Resistance Stage - description including these important points (physiological resources, cortisol, adrenal cortex, glucose, damaging)
• Exhaustion Stage - description including these important points (depleted resources, stress related illnesses, immune system)

Selye 1936 studied rats in order to develop this theory. He exposed them to harmful experiences (e.g. surgical injury, drugs). His studies with the rats showedthe 3 stages in response.

Stress is a physical and psychological response experienced when we ecounter a threat that we do not feel we can cope with. Such stressors can come from the environment around us, for example loud noise, crowds or too much work.

The physical and psychological changes that occur when we are stressed are adaptive - they have evolved to help us survive. 

According to Hans Selye (1956), the General Adaptation Syndrome represents the body's defence against stress. Selye suggested that our responses to stress are universal, i.e. we all have the same pattern of physiological responses. These responses include the release of stress hormones (e.g. adrenaline), release of glucose from the liver, rapid heartbeat, breathlessness, and increased blood supply to the muscles. In other words, when placed under stress we go into 'fight or flight' mode.

Selye defined stress as: 'the individual's physiological response, mediated largely by the autonomic nervous system and the endocrine system, to any demands made on the individual.' He proposed that there are three stages in General Adaptation Syndrome: Alarm, resistance, exhaustion.

In the alarm stage, the hypothalamus recieves a signal which is sent to the autonomic nervous system which produces high levels of adrenaline from the adrenal glands in the kidneys, and other hormones, to prepare the body for 'fight or flight'. There is a brief initial shock phase when blood pressure and muscle tension drop. Resistance to the stressor is reduced, but this is quickly followed by the counter-shock phase when the body's physiological defenses swing into action. The bodily changes caused by the ANS help us to prepare for action, e.g. faster heart and breathing rate supply more oxygen and blood to the muscles to give us energy to run away. If the threat/stressor subsides, the ANS returns the body to normal.

In the resistance stage, the body continues to use its physiological resources to resist the effects of the stressor. During this stage, hormones are released to sustain the body's defence reactions. Such hormones include cortisol, which is released from the adrenal cortex and breaks down fats and releases glucose from the liver to provide energy. Persistently elevated hormone levels are damaging and lead to the exhaustion stage.

In the exhaustion stage, the physiological systems become depleted and ineffective, and stress-related illnesses (e.g. high blood pressure, heart disease) become more likely. Under prolonged stress the immune system becomes weakened. Selye 1956 also found that if a second source of stress was introduced during the exhaustion stage, it could have devastating consequences for the health of the individual.

Selye 1936 initially studied rats that were exposed to harmful experiences (e.g. surgical injury, drugs, cutting spinal cord). His studies with the rats showed that there were 3 stages in response - 1) shrinkage of immune system, ulcers, etc. 2) function of organs returned to normal when treatment was dicontinued. 3) With continued treatment, there was a return to symptoms shown in stage 1.