Stress

What is Stress?

Selye - He defined stress as ‘the non-specific response of the body to any demand’. In other words stress is a generalised reaction to a demand placed on the body.

The Body’s Response to Stress:

Sympathetic Adrenal Medullary (SAM) System (fast acting)

The hypothalamus activates the sympathetic branch of the autonomic nervous system (ANS), which stimulates the adrenal medulla, which leads to the release of adrenaline and noradrenaline (fight or flight). This leads to the physiological changes associated with stress, e.g. increased heart rate, raised blood pressure, sweating and shaking.

Hypothalamic Pituitary Adrenal (HPA) axis (slow acting)

Also, the hypothalamus sends messages to the pituitary gland, which leads to the production of the hormone ACTH. This stimulates the adrenal cortex, which then produces cortisol (a stress hormone). This provides the steady flow of fuel necessary to deal with the demands of the situation.

The General Adaptation Syndrome (Seyle):

This is the model of how the stress response adapts physiological systems to a stressor.

· According to Seyle, stress is adaptive in the short term because it enables us to cope with or adapt to environmental demands.

· Prolonged stress, however, is very damaging

· Seyle first studied rats, and later hospital patients with various injuries and illnesses. He noticed they all seemed to show a similar pattern of bodily response.

· Alarm reaction stage –
- The threat or stressor is recognised and a response made to the alarm.
- The SAM system goes into action and adrenaline is produced.
- This leads to the fight or flight activity.

· Resistance stage –
- This is the stage of adaptation
- The parasympathetic system is being taxed to its’ limits
- The individual appears to be coping outwardly, but inwardly, physiological systems are beginning to fail.
- There is a reduction in growth hormone

Exhaustion stage –
- When stress is prolonged, the body can no longer maintain normal functioning.
- Initial fight or flight symptoms may reappear, such as increased heart rate.
- The adrenal gland may be damaged and the immune system is less effective.
- These changes can result in stress-related illness.