Lecture 6 Flashcards
What is the fight or flight response?
physiological responses that ready us for intense efforts, whether to confront a threat or to escape from it
Who wrote the wisom of the body?
walter B. connon, the pioneer of the stress response concept
Who is hans seyle?
pioneer of the concept of general adaptation syndrome
What are two types of stressors?
psychosocial stressors
biogenic stressors - extreme cold, no shelter, no food etc.
How does a psychosocial stressor work?
- must work through cognitive appraisal mechanics, cannot directly cause the stress response
- they are real or imagined environmental events
How does a biogenic stressor work?
Work directly on neurological triggering nuclei, no cognitive affective processing
e.g. caffeine, nicotine, pain, extreme heat/cold
What is eustress?
moderate or normal psychological stress
“good stress”
- positive form of stress that may be perceived as pleasurable
- it is in a positive response to demands
What are the effects of eustress?
can have similar physiological effects as distress: increased heart rate and elevated glucocorticoids
How long does distress take to occur?
developed over relatively long period of time however acute distress can also occur in response to a short, intense stressor
Therefore animal may be in distress even if it appears to recover rapidly after the removal of the stressor
What are some adaptations to stress responses?
- evolved to handle physical threats such as temperature changes or appearance of predator, psychological threats elicit the same response
- coping mechanisms
- activation of sympathetic NS and adrenal medulla
- secretion of stress hormones
- mobilization of immune system
- behaviour
What is stress?
complex term referring to psychological or physiological changes that occur in response to real or perceived threats to homeostasis - allostasis
What is allostasis?
process of achieving stability
What is an allostatic response?
active response to a stressor promotes adaptation
What is allostatic load?
allostatic systems are overstimulated or do not perform normally
What are the steps to a stress response?
stressor event-> cognitive appraisal and integration-> neurological triggering.) physiological response-> target organ activation-> coping behaviour
What is cognitive appraisal?
process of cognitive interpretation
What is affective integration?
blending and colouring of felt emotion into the cognitive interpretation
What does the cognitive-affective complex do?
represents how stressors are perceived
What are the anatomical epicenters of the brain?
brainstem
limbic system
What are the three physiological pathways of a stress response?
neural axis - stress response via neural innervation of target organs
neuroendocrine axis - fight/flight
endocrine axis - most chronic aspects of the stress response, greater intensity to activate
What are the three neural axes of a stress response?
sympathetic NS: generalized arousal within end organs - most common form of neural stress responsiveness - noradrenalin is responsible
parasympathetic NS: inhibition, slowing - ACh is responsible
neuromuscular system: prime target for immediate activate but limited ot ability to release ntunder chronically high stimulation
What are the pivotal organs in the fight or flight response?
amyglada: highest point of fight/flight origination
downward flow of neural impulses to the hypothalamus
descend through the thoracic spinal cord
innervating adrenal gland
resulting in a hormonal output of catecholamines
What is the sam system?
sympathetic adrenal medullary system:
- hypothalamus and sympathetic NS stimulate the adrenal medulla to release epinephrine and norepinephrine
- they initiate rapid activation of sympathetic NS
What is the adrenal cortical axis?
Hypothalamus (CRF)
->
Anterior Pituitary (ACTH)
->
Adrenal cortex (glucocorticoids, mineralocorticoids)
What is glucocorticoid release controlled by?
activity of the hypothalamic pituitary adrenal axis (HPA axis)
What is the somatotropic axis?
Hypothalamus (SRF)
->
Anterior Pituitary (GH)
->
Effect of GH (increase in FFA and glucose in blood)
What is the thyroid axis?
Hypothalamus (TRF)
->
Anterior pituitary (TSH)
->
Thyroid gland (T3 and T4)
What is the result of the thyroid axis?
increase in general metabolism, hr, heart contractility, peripheral vascular resistance and sensitivity of some tissues to catecholamines
What is the posterior pituitary axis?
- receives neural impulses from the supraoptic nuclei of the hypothalamus
- releases ADH (water retention) and oxytocin (birth)
What does chronic stress often lead to?
ill health
most of the harmful effects of stress are produced by prolonged secretion of glucocorticoids
What does prolonged secretion of glucocorticoids result in?
increase blood pressure, damage to muscle tissue, steroid diabetes, infertility, inhibition of growth, inhibition of inflammatory responses, suppression of the immune system
What animal are oesophago-gastric ulcers an issue in?
pigs
What occurs in the brain if there is long term exposure of glucocorticoids?
- destroys neurons located in hippocampal formation
- can create memory problems when we are older
- intense long-term stress can cause severe brain damage in primates
- stress of chronic pain has adverse effects of brain
What happens to the dorsomedial prefrontal cortex during exposure to early life stress?
reduces the volume of the dorsomedial prefrontal cortex
What is the effect of prenatal stress?
- interferes with normal development of hippocampus, leading to long-lasting malfunctions in learning and memory
- can affect brain development and produce changes for life
How can predictability impact the effect of stress?
animals that can predict the onset of stressful stimulus have a lower impact of the stressor
How does resilience impact stress responses?
- presence of various protective hormones and controlled exposure to stress related stimuli can promote resilience in the event of stress
- some experience during early life can reduce reactivity to stressful situations in adulthood
