Stress and physiology

Stress and physiology
The physiological consequences of stress have been studied extensively, mostly in the laboratory using the acute stress paradigm. This involves bringing participants into a controlled environment, putting them into a stressful situation (such as counting backwards, completing an intelligence task or giving an unprepared speech) and then recording any changes. This research has highlighted two main groups of physiological effects:
1 Sympathetic activation
When an event is appraised as stressful, it triggers responses in the sympathetic nervous system. This results in the production of catecholamines (adrenalin and noradrenalin), which causes changes in factors such as blood pressure, heart rate, sweating and pupil dilation. These changes are experienced subjectively as a feeling of increased arousal. This process is similar to the ‘fight or flight’ response described by Cannon. Sympathetic activation and prolonged production of adrenalin can result in:
1. blood clot formation n fat deposits
2. increased blood pressure n plaque formation
3. increased heart rate n immuno-suppression
4. irregular heart beats
These changes may increase the chances of heart disease and kidney disease, and leave the body open to infection.

2 Hypothalamic-pituitary-adrenocortical (HPA) activation
Stress also triggers changes in the HPA system. This results in increased levels of corticosteroids (cortisol), leading to more diffuse changes, such as the increased use of carbohydrate stores and a greater chance of inflammation. These changes constitute the background effect of stress, and cannot be detected by the individual. They are similar to the alarm, resistance and exhaustion stages of stress described by Selye as they show how chronic ongoing stress can be damaging to the body in the longer term. HPA activation and prolonged production of cortisol can result in:
1. decreased immune function
2. damage to neurons in the hippocampus These changes may increase the chances of infection, psychiatric problems and losses in memory and concentration.