Stress/Selye's Concept Flashcards
Who first described the concept of stress?
Hans Selye in 1930’s
“Specific neural, endocrine and immune effect upon exposure to noxious stimuli/pathogens”
What did Dantzer and Mormede suggest about stress in 1983?
“Environmental stressors exert their noxious effects not only through their physical qualities but through their psychological effects on the animal”
What determines the impact of stress on an organism? (9)
- Number
- Intensity
- Duration
- Transient vs chronic
- Temporal juxtaposition
- Interaction
- Age
- Experience/history/genetics
- Perception
- Adaptation
What are two types of stress?
Eustress (positive)
Distress (negative)
- Any all changes initiate stress which is not always detrimental
- Stress is context dependent : occurs when an individuals context is altered
- Psychological/physiological stress is unavoidable in life
What must happen in response to stress?
The organism must respond by adapting to the change
How does an organism adapt to stress?
Adaptation begins with activation of systems designed to maintain homeostasis
- Nervous, endocrine, immune
What is the result of a failure to adapt?
- Over-activity or inactivity of psychological systems
- increases wear and tear on body and brain
- Homeostasis perturbed chronically - internal state defining health is jeopardized
What are three behavioural responses to stress?
- Avoidance
- Displacement
- eg biting nails
- Reflexes
- eg pulling hand away from heat
What are 7 Neuro-endocrine responses to stress?
- Sympathetic vs Parasympathetic
- Hypothalamus (CRH, GnRH)
- Pituitary (GH, Prl, LH, TSH, ACTH)
- Adrenal (Aldosterone, NE, E, Cortisol)
- Thyroid (T3 and T4)
- Pancreas (insulin, glucose)
- Gonads (sex hormones)
HPA Axis is very important
What are 6 early behavioural responses/adaptations to stress?
(lion/zebra example)
- Altered cognition & attention span - facilitate adaptive neural pathways for coping
- Increased alertness
- Altered sensory threshold
- Sharpened memory and sensation
- Stress-induced analgesia
- Suppression of feeding behaviour
- Suppression of Reproductive behaviour
What are four early physiological responses and adaptations to stress?
- Oxygen and nutrients redirected to CNS and stressed body sites (muscle/lungs/heart)
- Rapid detoxification from toxic products (liver)
- Altered cardiovascular tone
- increased hr, co, stroke volume
- vasodilation of vessels in muscle
- vasoconstriction of vessels in gut
- Containment of the stress response
- stress response is only beneficial in Short-Term
Changes in which gland are thought to be critical adaptations to stress?
Changes in adrenal activity (Adrenocortical response)
What are 3 types of physical stress known to modulate cortisol secretion by the adrenal gland?
- Hypoglycemia (glucose regulation)
- Trauma
- broken bones
- burns
- surgery
- cold exposure
- infection
- Heavy exercise
What are 2 psychological stressors that are known to increase cortisol secretion by the adrenal gland?
- Acute anxiety
- anticipation of stressful situations
- novel situations
- Chronic anxiety
What is Selye’s definition of the stress response?
Stress is the sum of all non-specifici systemic reactions of the body which ensue upon long-term exposure to stress
- stressors of all different kinds elicit same response