Physiology of Chronic Stress Flashcards
Stressors include multiple domains. The three main domains are:
- emotional
- environmental
- physiological
Stress
is a condition/feeling/experience when a person perceives that demands excess the personal and social resources the individual is able to mobilise
some compensation is possible for limited
Stressors: Types:
- real
- imagined
- internal (spontaenous/uncosciously)
- external
Stress is how you react to what happens. Stress is a condition that precipitates
behavioural adjustment
behavioural adjustments can be good, bad, indifferent, conscious and unconscious
Quantifying Stress:
Holmes and Rahe Stress Scale is an inventory of 43 life events which predispose to stress-related illnesses, weighted according to their respective probability of doing so
Holmes-Rahe Stress Scale: Scores:
- <151 points = relatively low amount of life
change and low susceptibility to stress-
induced health breakdown - 150 -300 = 50% chance of health breakdown
in the next 2 years - 300+ = 80% chance of health breakdown in
the next 2 years
can be both psychiatric illness or somatic illness
Subtypes of Stress:
insert table
Cognitive Appraisal Mechanism:
- stressor precipitates behavioural adjustment
- primary appraisal is the initial interpreation
of stressor -> positive, irrelevant, potential
danger - if potentially dangerous
- secondary appraisal
- adequate internal/social resources to
manage - if insufficient resources, there is a lack of
resolution of primary and secondary
appraisal so stress response occurs
Acute Stress Response:
- adrenal medulla secretes hormones
- integrates the fight or flight response
- sympathetic division of autonomic nervous
system - increases heart rate
- increases BP
- increases RR
- increases bronchial dilation
- increased pupil diameter
- decreased GI activity
Acute Stress Response: How does it resolve?
- negative feedback loop
- resolves quickly
- once perceived threat is no longer
considered dangerous
Core structures that affect the HPA Axis:
- hypothalamus
- the pituitary gland
- adrenal glands
- adrenal cortex
- adrenal medulla
HPA Axis is a complex
neuroendocrine axis
Bi-directional communication between the HPA Axis and
the immune system via cytokine activity that can activate the HPA Axis
the HPA Axis modulates the immune response, with high levels of cortisol resulting in a suppression of immune functions
HPA Axis: Overview:
- negative feedback loop
- hypothalamus secretes CRH
- binds to pituitary
- pituitary secretes ATCH
- ATCH binds to adrenal cortex
- secretes glucocorticoids (gluose,
cortisol,steroids) but not anti-inflammatory - which binds back to hypothalamus and
pituitary to prevent more secretion of CRH,
ATCH
Evolutionary Arms Race
- adaptation and counter adaptation
- on a level of an organism
- on an interspecies level
HPA Axis:
- interaction of HPA axis and environment
maintain homeostasis and wellness,
prevents allostatic overload and distress
Optimally interactions of systems within the HPA Axis maintain homeostasis and wellness, preventing
allostatic overload and distress
Chronic Stress Exposure:
- induces changes within endocrine and
immune system functionality via the HPA
Axis - cortisol-awakening response malfunction
- always high cortisol
- immune system does not rest
- results in fatigue
Removal of stressor will always result in return to physiological function of immune system and HPA Axis
no
Allostasis
adaptive physiological changes due to the activation of homeostatic mechanisms in response to changing environment
can lead to allostatic overload
Allostatic Overload: Examples:
- elevated catecholamines
- HPA axis dysfunction
- excessive proinflammatory cytokine activity
Adverse Childhood Experiences can increase allostatic overload later in life and lead individuals into
social isolation, hostility, depression and both physical and psychiatric conditions
Adverse Childhood Experiences increasing risk of allostatic overload later in life is considered to be
a fatigue response due to the high energy consumption required attempt to resolve uncertainty to preserve safety
Hippocampus functions:
involved in learning and memory; damage to this structure causes cognitive impairment and interferes within the process of new learning
Hippocampal Changes: Adverse Childhood Experiences:
- reduced hippocampal volume
- especially in those who have been physically
or sexually abused
Cortisol can both increase the ability to encode/recall memories and decrease it:
- acute can increase
- chronic stress response will decrease
Stress can activated inflammatory response in the periphery.
True or False?
True but also in the brain
Transplacental Properties of Cortisol:
elevated circulating cortisol levels in mother can lead to low birth weight and preterm delivery for the neonate
