Chapter 11 Flashcards
What are the consequences of animals who cope effectively with stress?
live longer and leave more offspring
What are the key structures involved in stress mediating?
Hypothalamus-> Regulates hormonal responses
Pituitary gland-> Releases ACTH, triggering stress hormone
release.
Adrenal glands-> Secrete glucocorticoids (e.g., cortisol) that
modulate stress responses.
Other systems affected:
* Sympathetic nervous system (activates “fight or flight”).
* Parasympathetic nervous system (restores balance after stres
What is homeostasis?
The body’s ability to maintain a stable internal environment
Between which basic competing needs is energy shared?
- Growth
- Cellular maintenance
- Immune function
- Reproduction
- Thermogenesis (heat production)
What are the three types of stressors?
Environmental Stressors: Extreme temperatures, noise.
Physiological Stressors: Hunger, dehydration, illness.
Psychosocial Stressors: Social conflicts, lack of control in a situation.
What are some mediators that are activated by stressors?
Glucocorticoids
* Sympathetic neurotransmitters
* Cytokines (immune system signalling molecules)
* Metabolic hormones
—> influence each other dynamically
What factors can explain the individual differences in stress responses?
- Psychological makeup (e.g., resilience, coping strategies).
- Genetic predisposition.
- Developmental history (e.g., childhood stress exposure).
Social environment (support systems, hierarchy status). - Behavioral state (current activity and mindset
What are the two main endocrine systems involved during a stress response?
- Epinephrine (adrenaline) from the adrenal medulla
- Glucocorticoids from the adrenal cortex
Which are the hormones acting within seconds VS a few minutes after a stressor?
Within seconds of perceiving a stressor:
* The sympathetic nervous system secretes norepinephrine.
* The adrenal medullae release epinephrine.
A few minutes later:
* The adrenal cortex secretes glucocorticoid
What is the Cannon’s Emergency Theory?
Proposed by Walter Cannon in 1915
- Suggested that epinephrine secretion increases in response to stressors to
facilitate adaptation.
Epinephrine acts first because even a small increase leads to significant
changes in:
- Respiration rate
- Heart rate
- Blood pressure
Which Axis regulate hormonal responses to stress?
Hypothalamic-Pituitary-Adrenal (HPA)
Which hormones other than norepineprhine and epinephrine are released a bit later by the HPA?
CRH-> ACTH and endorphin
Corticosterone
Prolactin and vasopressin
What is the General Adaptation Syndrome?
Nonspecific nature of the stress response
- discovered by Hans Selye whil studying ovarian hormones
What are George Chrousos and Robert Sapolsky’s theory of the homeostatic model of stress?
George Chrousos: Stress is the body’s recognition of a stressor and the attempt to reestablish homeostasis.
Robert Sapolsky: A stressor is anything that disrupts homeostasis, such as injury, illness, or environmental extreme
What are the limitations of the Homeostatic model?
Non-stressful Homeostatic Disruptions-> eating or reproduction
Psychological Stressors-> Events like public speaking or claustrophobia
induce full physiological stress responses.
Individual Variation: Different individuals perceive stressors differently
Physiological Overlap: Both stressful and pleasurable experiences (e.g.,winning a lottery) trigger similar physiological responses
What is Kim and Diamond’s Three part definition of stress?
Arousal by Aversive Stimuli: Stress increases physiological arousal (hormones, EEG/ECG activity)
Perceived Aversiveness: Stress occurs only if an individual perceives a stimulus as aversive.
Controllability: Stress intensity depends on the perceived ability to control the situation
What is the Reactive Scope Model?
Integrating Homeostasis, Allostasis, and Stress
Four key ranges of physiological response:
- Predictive Homeostasis: Daily and seasonal variations in biological mediators.
- Reactive Homeostasis: Necessary fluctuations to respond to immediate threats.
- Homeostatic Overload: Excessive responses leading to long-term health risks.
- Homeostatic Failure: Insufficient responses leading to short-term health risks.
What are some examples of immediate physiological effects of stress?
- Increased respiration and cardiovascular rates.
- Increased glucose and oxygen availability.
- Blood flow redirected to muscles, away from digestion.
- Pain and inflammation responses inhibited by endorphins and endocannabinoids.
- Non-essential functions (growth, reproduction, digestion, some immune functions) are suppressed.
- Some immune functions, such as immune cell trafficking to the skin, are enhanced.
What is the role of CRH in the hypotalamus and in the amygdala?
Hypothalamus: regulates HPA axis.
Amygdala: modulates anxiety responses
What are the two types of corticosteroid receptors in the hippocampus?
Type I (MRs): Engage under baseline
conditions, maintaining homeostasis.
Type II (GRs): Engage during stress, providing negative feedback to regulate glucocorticoid
levels.
How does the endocannabinoid system regulate stress?
Endocannabinoids mediate glucocorticoid effects
on stress responses.
* Corticosterone activates membrane-bound
glucocorticoid receptors (mbGR).
* This induces endocannabinoid ligand production,
which binds to CB1 receptors, inhibiting GABA
secretion.
* Reduced GABA inhibition leads to increased
norepinephrine secretion, modulating stress
What are the endocrine risks due to chronic stress?
- Vasopressin increases blood volume and pressure, enhances memory consolidation, and contributes to aggression.
- Prolactin suppresses reproductive functions through multiple pathways.
- Glucagon increases energy availability, while insulin secretion is inhibited.
- Endorphins and enkephalins are released to suppress pain perception
What did the cold pressor study show about the impact of early experiences?
Children who overreacted to the cold pressor test were more likely to develop cardiovascular disease later in life.
Suggests a strong link between early physiological responses to stress and long-term health outcome
Which study shows that perceived stress matter as much as actual stress?
Two monkeys were deprived of food to examine how
individual differences affect stress responses.
- Both experienced energy deficits, but one received a
nonnutritive flavored placebo.
- The monkey that received the placebo did NOT show an
increase in glucocorticoid secretion.
- The other monkey (without placebo) displayed elevated
stress hormone levels.
