Biomedical model
- Rooted in the idea that mind and body are distinct, separable entities (mind-body dualism).
- Looks to bodily factors, rather than the mind, for explanations of health and disease.
- Cannot explain change in patterns of disease, and why, when exposed to a virus, only some people get sick.
Biopsychosocial model
A model of health that considers the effects of biological, psychological, and social factors on health and illness.
Changing patterns of diseases
- Until the early 20th century, acute infectious diseases (e.g., tuberculosis, pneumonia) leading causes of death in Canada and the US.
- In present day, chronic illnesses (e.g., heart disease, cancer) are the main contributors to death (as well as disability).
Can stress make us sick?
Have begun to recognize that emotional disturbances—or what we refer to colloquially as “stress”—can have a negative impact on our health, causing or exacerbating chronic
disease.
Everyday stress
- Stress is ubiquitous
- Psychological and social disruptions often reported as culprits
- Prevalence of stress-related disease may be attributed to chronic activation of systems meant for acute responses
- Humans are really good at generating problems in our heads using our prefrontal corteces (mental time travel), which leads to rumination: the repetitive thinking or dwelling on negative feelings and distress and their causes and consequences.
- Even thinking about something stressdul elicits the same psychological responses as the stressdul event itself!
Hans Selye and his rat experiments
- Was studying a newly discovered ovarian
hormone - Rats injected with hormone developed peptic ulcers, greatly enlarged adrenal glands, shrunken immune tissues
- Exciting discovery—but problem with the
research method? No control group! - Added a control group—and observed the
exact same effects! - Due to stress!
General adaptation syndrome
- The body mounts a similar set of responses (general adaptation syndrome; what we now call stress) to a broad array of stressors
- Stress is “the nonspecific response of the body to any demand” (Selye, 1976)
- Unfolds in three stages: alarm, resistance, and exhaustion
- These responses mobilize the organism for action; but if stressors go on for too long, they can make you sick
Initiation of the stress response
- In response to stressful events two processes are called into action
- Both are controlled by the hypothalamus, which plays a key role in coordinating motivated behaviours required for survival, including the fight-or-flight response
- Hypothalamus receives input from a set of regions that serve as a ‘neural alarm system’: dorsal anterior cingulate cortex (dACC), anterior insula (AI). But also the amygdala.
Sympathetic nervous system / Sympathetic-adreno-medullary (SAM) axis
Physiological system that governs the body’s immediate response to a stressful event, enabling the ability to fight or flee.
1) The hypothalamus initiates sympathetic nervous system arousal
2) Stimulates a part of of the adrenal glands, which secrete chemical messengers including epinephrine.
3) Leads to increased blood pressure, heart rate, sweating.
Ex: When crossing the street and almost getting hit by a car
Parasympathetic nervous system
- The “brake pedal”
- Acts antagonistically to the sympathetic nervous system; counterbalances
- Once the emergency has passed, restores the
body to a normal state, allowing resources to be devoted to life-sustaining processes such as
digestion and growth (rest + digest)
Hypothalamic-pituitary-adrenal (HPA) axis
1) Hypothalamus initiates a chemical cascade that stimulates pituitary gland (the “master” gland)
2) Hormone released by the pituitary stimulate a different part of the adrenal glands, which in turn releases hormones including cortisol
3) Cortisol mobilizes sugar for fuel, increases heart rate & blood pressure, directs attention toward threat, contributes to formation of “flashbulb memories”
- Slower system; kicks in approximately 20-30 mins after stressor
Allostatic load
The compromise of the HPA axis’ functioning due to sustained activation.
- Normally, cortisol helps the body return to its steady state following stress by inhibiting release of CRF from the hypothalamus (i.e., negative feedback). “Let’s start wrapping this up” signal.
But, with allostatic load…
- Daily cortisol patterns may be altered
- While cortisol normally inhibits inflammation, prolonged stress can result in increased glucocorticoid resistance of immune cells, leading to heightened inflammation
- Chronic inflammation implicated in a large number of diseases, including depression, cancer, diabetes, cardiovascular disease
How stress takes its toll
- Prolonged experiences of stress compromise
the immune system - Stress can slow down wound healing
- Cardiovascular system: Chronic activation of the sympathetic system & HPA axis can lead to the buildup of plaque on arterial walls, which increases risk of a heart attack
Ex: When participants were exposed to a cold virus, those reported experiencing chronic stressors were more likely to develop a cold in response to the virus.
Ex: Dental students’ wounds take longer to heal during exam period (vs. summer vacation).
Are all stressors created equal?
Stressors that are uncontrollable (harder to control or escapte) are more stressful .
Trier social stress test (TSST)
Lab paradigm for inducing physiological
and psychological stress.
- Consists of interview speech given in front
of panel of judges (about your candidacy for a job position), followed by surprise
mental math task
- Judges remain impassive, withhold feedback (“stone-faced)
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What makes laboratory stress paradigms stressful?
A meta-analysis of 208 laboratory studies of acute psychological stress identified two
key factors in eliciting a physiological stress response:
- Uncontrollability. In TSST: lack of social feedback, surprise math task, as you can’t gauge how you’re doing.
- Social-evaluative threat (possibility that the self could be negatively judged by
others). The key ingredienct (would not see same stress response without this). Tasks with a social evaluative component associated with an effect size 3X as large as effect size for tasks without such a component.
Stressors
The events that are most likely to be stressful.
Perceived stress
A subjective evaluation of stress (the event may stressful to some and not others) in response to events, depending on appraisal (shapes our perception of stress).
Stress appraisal theory
Appraisals of an event and our role in it shape our emotional experience of the event, and our physiological reactions to it.
- This theory postulates that stress is what happens when the demands of the situation exceed our ability to cope.
Two broad categories of appraisals: primary and secondary.
Primary appraisal
A person’s perception of the demands or challenges of a given situation.
- Is the event positive, negative, or neutral?
- If negative, to what extent is it harmful, threatening for the future, or challenging?
Ex A: Event is negative (who loves writing exams?) If I don’t do well on this exam, it will destroy my chances of getting into med school (high threat).
Ex B: Event is negative (who loves writing exams?) But it’s an opportunity to demonstrate how much I’ve learned and impress the prof (challenge). And if I don’t do well—well, it’s just one exam (low threat).
Secondary appraisal
A person’s perception of his or her ability to deal with the demands of a given situation.
- Are coping abilities and resources sufficient to deal with and overcome the harm, threat, or challenge posed by the event
Ex A: I’m just no good at this subject. I don’t have enough time to study.
Ex B: I’m good at this subject so I will be able to master
the material. I have plenty of time to study. My friend who took this course last year can help me go over any material I don’t understand.
Stress appraisals
Ultimately, the subjective experience of stress
results from the balancing of primary and
secondary appraisals.
- Perceived stress is high when the primary
appraisal of the situation’s demands exceeds
the secondary appraisal of your ability to meet
those demands.
E.g., High harm/threat + low coping = substantial stress
Challenge reactivity
A cardiovascular pattern of response whereby the heart pumps out more blood and the
vasculature dilates, allowing efficient
circulation through the body.
You feel as though you have the resources to meet the demands of the situation.
Threat reactivity
A cardiovascular pattern of response whereby the heart pumps out more blood but the
vasculature constricts, preventing efficient circulation through the body.
Can negatively impact health!
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Unit 1: Welcome To Psychology (Chapter 1)30
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Unit 2: Research Methods In Psychology (Chapter 2)84
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Unit 3: Genetics & Evolutionary Foundations Of Behaviour (Chapter 3)53
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Unit 4: Biological Bases Of Bahviour (Chapter 3)124
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Unit 5: Sensation & Perception (Chapter 4)105
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Unit 6: Learning (Chapter 6)101
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Unit 7: Consciousness (Chapter 5)87
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Unit 8: Memory (Chapter 7)80
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Unit 9: Motivation and Emotion (Chapter 9)96
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Unit 10 (Chapter 15)95
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Unit 11 (Chapter 12)81
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Unit 12 (Chapters 13 & 14)124
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Unit 13 (Chapter 10)35
