Stress

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Stress

Based on a judgement that we make if our bodies can handle the stressors presented to us by the environment

It all depends on if we have the resources to cope or not.

These judgements are made in the cerebral cortex in the brain – if judged to be stressor it sends signals to the hypothalamus to trigger response to stress.

Responses to all stimuli similar

Sympathomedullary pathway:

Fight or flight response – first stage

This is a response to acute stress

Sympathetic branch of ANS activated – causes adrenal medulla to release adrenaline and noradrenaline into blood

This causes heart and breathing rate to increase, digestion decreases

Hypothalamic Pituitary Adrenal System

Chronic stress response

Uses lots of bodily resources

Provides fuel for body

Releases hormones = corticrotropin (hypothalamus), adrenocorticotropic (pituitary gland signals release) , cortisol (adrenal cortex produces after detection of level of ACTH)

Role of cortisol

Most common

Converts protein to glucose to provide energy

But there are negative effects such as high levels of this can weaken immune system and have negative effects on memory

General Adaptation System

Selye

Describes physiological responses

3 stages of adaptation – alarm reaction, resistance and exhaustion

Alarm reaction = stressor perceived, body prepares for fight or flight, physiological changes like heart and breathing rate increase

Resistance = body tries to resist stressor, uses lots of resources, PNS activated to conserve energy

Exhaustion = stress now chronic, adrenal glands and immune system could become damaged, illness can occur

Evaluation of GAS

Strength = support with research, Selye subjected rats to several stressors such as extreme cold and found the same responses occurred regardless of what the stressor was – this can be demonstrated in reality

Weakness = generalised nature is questionable, Mason replicated Selye’s study and procedure using 7 different stressors on monkeys, he measured urinary cortisol levels and found varying levels on stressor such as cold increased cortisol and heat decreased cortisol. – this challenges the validity of the model and shows different stressors produce different responses.

As threats were mostly environmental in the past, the hypothalamic pituitary adrenal system was an evolutionary advantage. But now threats are often psychological, so this system may not be advantageous

Role of stress in illness:

These reactions are beneficial at times as they prepare us to deal with dangerous situations

But health is affected

Stress has effect on cardiovascular system, elevated stress levels have been shown to increase blood pressure (job strain, marital conflict)

Immune system affected.

Cortisol suppresses the HPA

Direct = cortisol inhibits the production of lymphocytes

Indirect = stress influences life style choices such as smoking and drinking

Research into chronic stress and immune system

Looking after relatives who are ill

Kiecolt – Glaser 1991

Longitudinal study

Procedure = 2 groups, Group 1 – caregivers looking after relative with Alzheimers, Group 2 – matched group of non caregivers

Findings = over 13 months, caregivers showed increase in antibodies to EBV virus, no increase in control group, caregivers had more illnesses and higher levels of depression

Preparing for exams

Kiecolt – Glaser 1984

Procedure = 75 medical students studied, they gave blood samples twice (one before the exam period and one on day of exam) – also completed questionnaires and self-report of symptoms.

Findings = activity of NK and Killer T cells decreased between first and second sample – evidence of immune response being suppressed by common stressor