ICL 6.0: Stress

Question 1

what is the stress theory?

Answer 1

adaptation aka maintaining an internal environment, is the essential process of life

adaptation occurs at all levels of life (cellular through organism)

the human adaptive system is a complex interconnection of organ systems maintaining organism integrity and adapt to the external environment

the adaptive processes can become maladaptive = STRESS –> maladaptation of the adaptive process results in organismic distress, strain, and disease

the primary organ of adaptation is the BRAIN

Question 2

what is the primary organ of adaptation?

Answer 2

the brain!

the CNS and its extensions and key to the adaptive process associated with stress theory

Question 3

why is stress theory important?

Answer 3

genetics and the interaction of the person’s constitution with the environmental aspects of life and the stress responses that occur are what lead to depression, anxiety, schizophrenia, etc.

mental Illness models often use the Stress-Diathesis concept to explain etiology of mental illness –> this stress theory provides a dynamic model that informs how to treat the illness effectively and provides a model that informs the provision of health care services across the spectrum of diseases and across the life cycle

so we look at the environments that we’re providing healthcare in, what are we addressing in the person’s psychosocial or physical environment to elevate and minimize the effects of stress on a person

Question 4

how is organ function controlled by the brain?

Answer 4

vital organs have intrinsic controls and ANS ganglionic reflex loops that maintain operation under limited demand

rapid changes in demand require higher brain centers to activate, regulate and coordinate organ responses

the stress response involves the systems maintaining organism integrity (homeostatic controls) –> these include the ANS, neuroendocrine system, and the endocrine system

Question 5

what is the pivotal organ involved in the fight-or-flight response?

Answer 5

adrenal medulla pf the adrenal gland

during sympathetic activation, there is NE and epinephrine (80%) release

when the sympathetic nervous system has outflow in the stress response, that direct innervation is happening extremely rapidly in all the organs that it stimulates

however, then when the neuroendocrine response via the adrenal medulla maintains this sympathetic response, the effect is functionally identical to direct sympathetic innervation but there is a 20-30 second delay in onset then a 10x increase in effect duration

Question 6

what is the chain of structures involved in the neuroendocrine sympathetic response?

Answer 6

central amygdala –> lateral hypothalamus –> sympathetic nerves –> adrenal medulla –> epinephrine –> increased HR, blood flow to muscles, breakdown of glycogen and airflow to lungs

Question 7

what are the effects of adrenal medullary stimulation?

Answer 7

this is the neuroendocrine response:

Increased arterial blood pressure

Increased blood supply to the brain

Increased heart rate and cardiac output

Increased stimulation of skeletal muscles

Increased plasma free fatty acids, tryglycerides, cholesterol

Increase release of endogenous opioids

Decreased blood flow to kidneys

Decreased blood flow to GI system

Decreased blood flow to skin

Question 8

what is the HPA axis?

Answer 8

release of cortisol via the hypothalamic pituitary adrenal axis as a response to stress!

corticotrophin releasing factor (CRF) is released through the hypothalamic-hypophyseal portal system from the hypothalamus to the anterior pituitary

this stimulates the release of ACTH from the anterior pituitary into the circulation which then triggers the release of cortisol and corticosterone from the adrenal cortex

cortisol then has a negative feedback on the anterior pituitary and hypothalamus to inhibit the release of too much cortisol

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Question 9

what is the normal rhythm of cortisol release in the body?

Answer 9

cortisol has a diurnal rhythm aka a daily rhythm where it tends to peak around 4 in the morning and then it has a slow decline throughout the day

this operates separately from the pulsing that occurs with a stress response

Question 10

what are the effects of cortisol/glucocorticoid hormones?

Answer 10

1. increased glucose production
2. increased urea production
3. increased release of free fatty acids into systemic circulation
4. suppression of immune mechanisms
5. increased ketone body production
6. enhancement of catecholamine synthesis in the adrenal medula
7. inhibition of inflammation

so the effects of cortisol are in some ways providing a lot of energy for the body to utilize during a stress response but the inhibition of inflammation and the suppression of the immune system are more designed as a protection for the body while it’s in the stress response from being overwhelmed by immune mechanisms and being able to flee effectively; you’ll experience the inflammation later

Question 11

how does stress effect the immune system?

Answer 11

stress inhibits inflammation and suppresses immune mechanisms

the immune system can signal the CNS with cytokines through multiple pathways –> cytokines are small secreted proteins which mediate and regulate immunity

one pathway that the CNS regulates the immune system through is the the pituitary-adrenocortical axis (HPA)

cortisol can facilitate and inhibit immune function –> lower levels facilitate the immune system while higher stress levels of cortisol inhibit

immune cells have receptors for epinephrine –> stress related secretion of epinephrine can enhance and/or inhibit immune function = very complex interaction

organs of the immune system are innervated by both branches of the ANS; both the sympathetic and parasympathetic

Question 12

what are the 2 main models of the stress response?

Answer 12

1. psychological appraisal and response model of stress
2. neurological block model of CNS areas involved in appraisal and response

so we’re going to be look at how does the stress experience happen and how is it triggered by psychological factors and what are the brain areas associated with that –> the implication is that how we perceive an event really drives our stress response, it’s not just about the event itself

Question 13

what is the psychological appraisal and response model of stress?

Answer 13

appraisal processes are key to whether or not there is some kind of stress response

the appraisal processes are divided into primary and secondary

the role of the appraisal processes is to both determine whether an experience/event has a threat potential and whether or not the organism has the resources to cope with that threat potential

Lazarus said that the primary decision about whether something is a threat happens very quickly and is based on our beliefs and commitments in life –> beliefs and commitments can be divided into things that are conscious and unconscious that occurred early in life

if our primary belief system determines that something is a not a threat or challenge we ignore it and stress won’t occur; but if we do determine it’s a threat or challenge, we move on to secondary processing and what our mind does it look at resources, options and the effectiveness of being able to deal with the stressor which will lead to some kind of coping behavior

a coping behavior can be a behavioral or psychological response –> your behavioral and psychological responses then cause biological responses that will then go impact the primary decisions; so if your psycholiglca and behavioral responses are good and work to calm you down then your biological responses will also do the same and that will go back and tell your primary process that you can handle this stressor

Question 14

what is the neurological block model of CNS areas involved in appraisal and response during stress?

Answer 14

1. the whole process of taking in the stress happens in the association areas, prefrontal cortex and hippocampus
2. then emotions are generated based on your appraisal of the stress in the prefrontal-amygdala and insula-hippocampus connections
3. these emotions then send feedback to the cortex and limbic system via the brainstem aminergic nuclei such as the locus ceruleus, raphe nuclei, and ventral segmental nucleus which release NE, serotonin, and dopamine

the emotions also initiate autonomic and endocrine response in the hypothalamus and paraventricular nucleus

4. this activation of the autonomic system drive the stress response which involves the nucleus of the solitary tract, intermediolateral cell column, pituitary gland and adrenal gland like we talked about earlier

Question 15

how do we measure stress?

Answer 15

1. the life events-Holmes scale and the Rahe-social readjustment rating scale
2. Hassles and Uplifts scale

Question 16

what is the life events-Holmes scale and the Rahe-social readjustment rating scale?

Answer 16

43 items on the scale-each life event has a relative number of stress units assigned – list each item that has occurred in the last 12 months

can include death of a spouse, divorce, marital separation, jail, death of a family member, personal injury or illness, marriage, fired at work, retirement

this gives a quantitative index of stress following a situation requiring adjustment

Question 17

how does age, sex, marital status and social class effect people’s life events-Holmes scale and the Rahe-social readjustment rating scale stress score?

Answer 17

there is significant variability that exists among groups in the perception of life events and the frequency of events

1. age: younger people have more life events than older but the ones that older people face are worse
2. sex: women tend to have greater life event scores than men
3. marital status: single, separated and divorced people accumulate a larger number of events
4. social class: inconsistent relationship with life events

Question 18

what is the Hassles and Uplifts stress scale?

Answer 18

there’s 117 hassles and 135 uplifts that assess the daily and cumulative impact of everyday demands

Hassles scale was found to be a better predictor of subsequent and concurrent psychological symptoms than the life events scale – probably because it’s measuring immediate things/events; it’s not going to tell you an accumulated score

Question 19

what are the physiological changes seen with stress?

Answer 19

1. cortisol
2. heart rate
3. catecholamines
4. immune suppression

it can be any biological endpoint of the stress response system!

however, physiological measures are complicated by inter-subject variability or intra-subject variability due to diurnal variations or situational factors

Question 20

what are the neurological changes seen with stress?

Answer 20

EEG or FMRI of brain activity shows changes during stressor or recovery from stressor period

Question 21

what can plasma cortisol tell you?

Answer 21

it indicates the dynamic state of the negative feedback loop in the cortisol regulation

researchers looked at the variability in plasma cortisol while people were in a float tank vs. not – mean levels and the variability of cortisol decreased (:

Question 22

what is Selyes Gas’s model of stress and illness?

Answer 22

the general adaptation syndrome which is divided into 3 phases:

1. alarm
2. resistance
3. exhaustion

he said the exhaustion phase was what was primarily connected to the illness situations

Question 23

what happens during the alarm phase of Selyes Gas’s model of stress and illness?

Answer 23

1. enlargement of adrenal cortex
2. enlargement of lymphatic system
3. increase in hormone levels
4. response to a specific stressor
5. epinephrine release associated with high levels of physiological arousal and negative affect
6. heightened susceptibility to illness

if the stress is prolonged, slower components of GAS are set into motion with stage II

Question 24

what happens during the resistance phase of Selyes Gas’s model of stress and illness?

Answer 24

1. shrinkage of adrenal cortex
2. lymph nodes closer to normal size
3. hormone levels sustained
4. physiological arousal stays high, but parasympathetic branch of the ANS counteracts
5. individual under resistance can endure the stressor and resist further debilitating effects from the stressor
6. heightened sensitivity to stress

if stress continues at intense levels, hormone reserves are depleted, fatigue sets in and you move into stage III

Question 25

what happens during the exhaustion phase of Selyes Gas’s model of stress and illness?

Answer 25

1. dnlargement /dysfunction of lymphatic structures
2. increase in hormone levels
   depletion of adaptive hormones
3. decreased ability to resist either the original or extraneous stressors
4. affective experience which is often depression

Question 26

what is homeostasis?

Answer 26

describes mechanisms that hold constant a controlled variable by sensing its deviation from a “setpoint” and feeding back to correct the error

emphasis is on steady state and optimal set points

Question 27

what is allostasis?

Answer 27

mechanisms that change the controlled variable by predicting what level will be needed and overriding local feedback to meet anticipated demand

emphasis is on optimal operating ranges of physiological systems, setpoints based on system prediction of demand

this is the stress response!!

Question 28

what is the homeostasis vs. allostasis stress model?

Answer 28

Peter Sterling and Joseph Eyer

in allostasis, prior knowledge leads to a prediction of the demand which effects the control system of homeostasis – homeostasis is the control system without any prior knowledge

our brain has the ability to override set points that are normally driven by more biological mechanisms –> for example, your BP set point is pre-set by certain biological factors but if you have stress responses in the environment, it could override the biological set point and drive the BP higher

allostasis and allostatic load provide a dynamic model of adaptation leading to maladaptation resulting in organismic distress that can be applied to both physical and mental illness

Question 29

what is allostatic load?

Answer 29

McEwen said that the allostatic load represents the cumulative, multi-system view of physiological toll that may be exacted on the body through attempts at adaptation

so if you have an allostatic system trying to respond to an external threat and it’s raised the BP and keeps it there for a period of time, this creates an allostatic load! it’s a physiological toll from trying to maintain that BP high

if allostasis keeps occurring over and over in ways that become dysfunction, you end up with allostatic load instead of adaptation

Question 30

what is allostatic overload?

Answer 30

when the allostatic load continues for long periods becoming independent of original adaptation effort

Question 31

what 4 mechanisms could result in allostatic load?

Answer 31

1. repeated hits
2. lack of adaptation to the same stressor
3. prolonged response without recovery = failure to shut off either the hormonal stress response or to display the normal trough of the diurnal cortisol pattern
4. inadequate response; physiological response promote stress responding/adaptation but they also have protective mechanisms! inadequate hormonal stress response which allows other systems, such as the inflammatory cytokines, to become overactive

normally there’s an increase of stress and an increase in physiologic response but then you deal with it and the physiological response goes down

Question 32

higher allostatic load scores are associated with what?

Answer 32

1. poorer cognitive and physical functioning
2. predicted larger decrements in cognitive and physical functioning
3. associated with an increased risk for the incidence of cardiovascular disease, independent of sociodemographic and health status risk factors

Question 33

higher baseline allostatic load scores are associated with what?

Answer 33

1. significantly increased risk for 7 year mortality

2. declines in cognitive and physical functioning

Question 34

how is the concept of allostatic load associated with mood disorders?

Answer 34

allostatic states leading to allostatic load produce cumulative changes in both brain and body

1. amygdala hyperactivity
2. HPA dysregulation which results from disruption of normal sleep patterns
3. delayed atrophy of hippocampus and prefrontal cortex from high levels of cortisol –> the hippocampus is the key in shutting off the HPA axis after psychological stressors
4. abdominal obesity and bone mineral loss

5.