Neuro 4 Flashcards
stress
reaction to harm or threat
stressors
stimuli that cause stress
acute stress
stressor that is sudden and short term
chronic stress
stressor is ongoing and long-term
are stressors physical or psychological
both
Hans Selye
coined the term ‘stress’. he was an endocrinologist.
first he said stress is “the nonspecific response of the body to any demand made to it” -> emphasized the body’s physiological reaction to various stressors, regardless of whether they were physical, emotional, or environmental.
later he said “stress is not what happens to you but how you react to it” ->This highlighted the role of perception and individual response in determining the effects of stress on health.
chronic psychological stress
most clearly linked to ill health. In the short term, stress is adaptive, in the long term it is maladaptive.
eustress vs distress
good stress vs bad stress
when a stressor occurs, what happens in the brain- two system view
- HPA system
- Sympathetic nervous system
HPA system (function + neural circuitry)
The HPA system (Hypothalamic-Pituitary-Adrenal axis) is a key part of the body’s stress response. It uses hormonal and neural signaling.
Order:
Hypothalamus -> Anterior Pituitary -> Adrenal Cortex -> Glucocorticoids
sympathetic nervous system pathway
sympathetic nervous system->adrenal medulla-> makes and secretes norepinephrine and epinephrine
stress response immediate
Sympathetic nervous system (SNS)
- works through neural mechanisms
- matter of seconds
Delayed stress response + process
The HPA axis is a central stress-response system involving both neural and hormonal mechanisms.
PROCESS
1. Neural and Hormonal Initiation:
hypothalamus activates and releases corticotropin-releasing hormone (CRH) into the bloodstream.
- Pituitary Activation:
CRH travels to the anterior pituitary, where it stimulates the secretion of adrenocorticotropic hormone (ACTH).
ACTH is then released into systemic circulation. - Adrenal Cortex Activation:
ACTH binds to receptors in the adrenal cortex. This triggers the synthesis and release of cortisol.
Hypothalamic pituitary adrenocortical
HPA
glucocorticoids
stress hormones produced/released by the adrenal gland during stress response. Particularly dense in the hippocampus.
Biological assessment of stress- SNS
ways to measure the biological assessment of stress via the Sympathetic Nervous System (SNS):
- norepinephrine and epinephrine levels - galvanic skin response - heart rate - blood pressure - salivary alpha amylase levels
Biological assessment of stress-HPA
cortisol/corticosterone levels
TSST
Trier social stress test.
- give speech and suddenly take away notes at last minute. judges force them to continue to the full time slot
experiment using Tsst
administer DEX (synthetic glucocorticoid) to block HPA acute response
administer PROP(beta blocker) to block SNS stress response
- DEX Group (Blocking the HPA Axis Response):
Old Findings:
In earlier studies, DEX effectively suppressed the HPA axis response, preventing the cortisol increase typically seen during stress.
Subjective stress ratings were lower, likely because cortisol suppression minimized the perception of physical stress signals.
New Findings:
Even in the DEX group, a smaller cortisol peak occurred before the presentation, though it was significantly lower than the placebo group.
Interestingly, the DEX group reported higher subjective stress compared to the placebo group before the presentation.
- PROP Group (Blocking the Sympathetic Nervous System Response):
Cortisol Findings: The PROP group showed higher cortisol levels than the placebo group, which is counterintuitive given that propranolol blocks the SNS (e.g., heart rate, blood pressure).
Subjective Stress Findings: Despite the physiological difference, there was no difference in subjective stress between the PROP and placebo groups.
how do we measure stress
self report
GSR (galvanic skin response)
heart rate
levels of cortisol or corticosterone in saliva or blood
Is self reported stress accurate
no, not always
circaidan rythmn and stress
Cortisol levels naturally rise at the end of the sleep period.
This increase is part of the body’s circadian rhythm and is not necessarily an indication of “stress” in the psychological sense. Instead, it reflects the body’s preparation for waking and starting the day, providing energy and alertness.
However, this rise can feel like stress if other factors are present, such as:
Chronic Stress: If someone is under ongoing stress, cortisol levels may be elevated even during sleep, leading to a heightened or dysregulated CAR. This can manifest as waking up feeling anxious or on edge.
Anticipatory Stress: If someone is dreading an upcoming event (e.g., a big presentation or test), the cortisol peak may be amplified, and they might interpret this as stress upon waking.
physical stressors (physiological/systemic)
disdurbance of physiological status that overwhelm specific hemoestatic mechanisms
- i.e. infection
- i.e. hemorrhage
psychological stress
involves stimuli or conditions that challenge an organism’s ability to maintain its current or anticipated homeostatic state.
Types:
threats to organisims current or anticipated state
social conflict
aversive environmental stimuli
