Physiology of Stress Flashcards
What is stress?
A mismatch between the perceived demands of the environment and the body’s ability to cope with this demand
When is the sympathomedullary pathway (SAM) used?
To create a short-term, immediate response to stress
How does the SAM pathway work?
1) When an individual perceives a stressor as threatening, the hypothalamus activates the sympathetic nervous system
2) this causes adrenal and no adrenaline to be released into bloodstream by adrenal medulla
3) these prepare the body for fight or flight
4) once stressor disappears, parasympathetic nervous system reduces fight or flight response
When is the hypothalamic pituitary-adrenal (HPA) system used?
To create a long-term, ongoing response to stress
When does the HPA system work?
How does the HPA system work?
At the same time as the SAM pathway
1) the hypothalamus releases CRH into bloodstream
2) CRH causes pituitary gland to secrete ACTH into bloodstream
3) ACTH stimulates adrenal cortex to release different stress-related hormones like cortisol
What role does cortisol play?
1) reduces immune system functioning resulting in less protection from infection meaning everything is geared to dealing with threat
2) maintains a steady supply of glucose in the bloodstream ensuring there is sufficient energy
3) reduces sensitivity to pain meaning an individual may not realise they have been injured until after conflict potentially enhancing survival
What is a strength of the short and long-term responses to stress?
Useful practical applications such as Addison’s disease where people can’t produce cortisol so body can’t mobilise energy to deal with stressor but knowledge of this has revolutionised treatment and means individuals can self-administer daily cortisol replacement therapy
What are the limitations of the short and long-term responses to stress?
1) purely physiological accounts are not sufficient to explain how the body responds to stress as Lazarus (1999) claims the body’s response is influenced by how an individual perceives a stressor suggesting cognitive factors should also be considered
2) gender bias is not considered as Taylor et al (2002) suggests females are more likely to adopt “tend and befriend” response due to higher levels of oxytocin whereas males hormones appear to reduce effects of oxytocin
What is the general adaption syndrome?
When animals are exposed to unpleasant stimuli, they display a universal response to all stressors. It protects body short-term but if stressor is prolonged, serious damage can occur
General = same response to all
Adaption = it is adaptive and body’s way to cope with extreme stress
Syndrome = several symptoms
What are the three stages of the GAS?
Alarm stage = threat is detected and immediate physiological response is shock. SAM and HPA systems triggered, fight or flight activated
Resistance stage = is stressor persists, body attempts to cope with demand. Activity initiated by adrenal medulla reduces so it looks like the body is coping but physiologically, things are deteriorating due to increased activity initiated by adrenal cortex
Exhaustion stage = if stressor is still present then body can no longer cope. Some initial symptoms from SAM pathway reappear (eg. Increased heart rate) and adrenal glands may be damaged from over-activity. Individuals now likely to suffer from diseases of adaption
What are the strengths of the general adaption system?
1) research support where Selye exposed rats to various types of harmful stimuli and noticed that a similar response was produced regardless of the stressor
2) useful practical applications as Selye was the first to identify a link between stress and illness which could lead to the development of stress reduction programmes
What are the limitations of the general adaption system?
1) does not consider individual differences as some people have cognitive coping strategies which enable them to deal with persistent stressors effectively without becoming ill, means GAS can’t be generalised
2) stress-related illnesses in exhaust action stage may not be due to depletion of resources because research has shown resources don’t become depleted, instead it is thought increased production of stress hormones causes illnesses
