stress response

Question 1

stress response

Answer 1

integrated reaction to stressors, broadly defined as real or perceived threats to homeostasis or wellbeing (herman et al)

Question 2

what does hpa stand for

Answer 2

hypothalamic pituitary adrenal axis

Question 3

what is hpa

Answer 3

-hallmark of stress response
-activation of hpa axis is mainly hormonal response to a stressor
-mobilises energy reserves ensuring organism can respond to actual and anticipated threat

Question 4

nervous system

Answer 4

CNS
PNS
sensory motor
(from motor) = somatic and autonomic
(from autonomic) = sympathetic and parasympathetic

Question 5

input to hpa

Answer 5

signals (visceral afferents) are received by brain stem noradrenergic neurons
-stimulate paraventricular nucleus (pvn)

Question 6

mechanism of hpa

Answer 6

hypothalamus -(CRH)- anterior pituitary -(ACTH)- adrenal cortex - CORT (NEG FEEDBACK LOOP, CYCLE REPEATS)

Question 7

crh

Answer 7

corticotropin releasing hormone

Question 8

acth

Answer 8

adrenocorticotropic hormone

Question 9

what is GR

Answer 9

glucocorticoid receptors

Question 10

MR

Answer 10

mineralocorticoid receptors

Question 11

what does GR do

Answer 11

GR mediates mobilisation of energy stores (liver, fat, muscles) inflammation and neural function

Question 12

what does MR do

Answer 12

important for basal circadian and ultradian rhythms

Question 13

output of HPA

Answer 13

stressor
hypothalamus

(from hypothalamus: pathway one)
CRH
anterior pituitary
ACTH
adrenal cortex
glucocorticoids
Cortisol

(from hypothalamus: pathway two)
fight or flight
sympathetic NS
adrenal medulla
adrenaline and noradrenaline

Question 14

how to chut down stress response

Answer 14

1 passive steroid clearance
2 neg feedback loop (when receptors detect cortisol, they signal back to hypothalamus to stop produce)

Question 15

acute stress

Answer 15

-efficiently drives HPA stress response and feedback mechanisms
-terminates response after stressor subsides
-stress response duration depends on stimulus duration, intensity and feedback

Question 16

LT stress and evolutionary theory

Answer 16

no need for LT stress as stressors were food, predation and water

Question 17

chronic stress

Answer 17

repeated or prolonged exposure to stressors

Question 18

stress response and chronic stress

Answer 18

stress response not designed for chronic stress

Question 19

McEwen and stellar allostasis

Answer 19

being able to adapt to perform optimally in stressful situations

Question 20

Mcewen and stellar allostatic load

Answer 20

mediators of stress response promote adaptation in the aftermath of acute stress
they contribute to wear and tear on body and brain as a result of being stressed out

Question 21

chronic stress as cumulative process

Answer 21

-adrenal cortex increases in size, becomes more sensitive to ACTH so cortisol amplified
-glucocorticoid sensitive immune organs e.g thymus undergo cell death and shrinkage
-loss of glucocorticoid feedback control of HPA axis associated with decreased GR in hippocampus

Question 22

habituation to homotypic stressor

Answer 22

herman et al
-repeated exposure to same stressor lowers cortisol response over time
-but organism still undergoes repeated stress
-lower HPA drive requires the MR
-paraventricular thalamic nucleus (PVT) is crucial

Question 23

facilitation

Answer 23

-hpa axis to new stressor is either maintained or heightened
-exposure to stressor 1 facilitates cortisol response to stressor 2
-faster onset of cortisol release and higher peak cortisol levels
-facilitation involves PVT

Question 24

habituation

Answer 24

response to severe stressor DO NOT REDUCE

Question 25

severity of the stressor facilitation

Answer 25

if either of 2 stimuli are sufficiently intense facilitation will override feedback inhibition

Question 26

chronic stress and health

Answer 26

rose and cobb
-job role = air traffic controller (high stress)
-looked at interaction between stress and hypertension
-2 groups: busy and less busy airport
-hypertension worse in workers of busy airport

Question 27

ST vs LT stressors

Answer 27

ST can be beneficial and help us survive
LT can be harmful

Question 28

modulation of stress response

Answer 28

-feedback model
-stressor – action – HPA to baseline (closed feedback allostasis)
-stressor – action not appropriate – HPA elevated (open loop allostatic load)

Question 29

Selye’s general adaption syngrome (GAS)

Answer 29

-father of stress research
-first person to use word stress
-universal response to range of stimuli

Question 30

perception of control (Henry)

Answer 30

-indiv diff lead to diff in the way people deal with stress
-perceptions of control result in diff patterns of neuroendocrine activation
-perceived ‘easy to handle’ = active coping response = sense of control = release of noradrenaline
-testosterone rises with success
-perceived ‘hard to handle’ = passive coping = behaviour less assured = loss of control = adrenaline rises

-less certainty = growing distress = ACTH and cortisol rises

Question 31

Van Holst’s tree shrews

Answer 31

-male tree shrews compete for dominance in large cage
-defeated animals feed safely in nesting box
-dominant has full control and access
-submissive waits till coast is clear while subdominant tries their luck
-8-12 day confrontation period
-cortisol of defeated submissive nearly doubled
-no change in relaxed dominant or defeated submissive
-testosterone elevated in dominant

Question 32

Lundberg et al research

Answer 32

-task 1 = turning off series of lights as they appear on board, pace was out of control
-task 2 = same task but could control pace, competitive but now rewarding
-both tasks = same degree of effort
-excretion of cortisol and adrenaline measured in urine
-adrenaline was same for both tasks
-higher cortisol when pace was forced