Stress Flashcards
What is stress, according to Sapolsky., (1994)?
- Anything that throws body out of homeostatic balance.
What are examples of sources of stressors?
- Environment (temp, noise)
- Physiological (food quality, water dep)
- Psychological (social subordination, novel situations)
What is considered stressful?
- Not defined from an outside event.
- Interpretation of an individual.
*what is stressful to someone, may not be stressful for someone else
What are the two different stress responses?
- Accute Stress Response
- Long-term Stress Response
What happens in the acute stress response?
- When something bad happens, the hypothalamus sends a neuronal signal.
- This activates the adrenal medullae to secrete adrenaline and nonadrenaline.
*nonadrenaline
What is norepinephrine?
- Always present in the body.
- Continuosly released into the blood stream.
- Narrows blood vessels to increase blood pressure.
*adrenaline
What is epinephrine?
- Only released when stressed.
- Increases heart rate and blood pressure.
- Brings more blood flow to brain/muscles.
- Prepares body for acute energetic response.
What do norepinephrine and epinephrine do?
- Stimulates the respiratory and cardiovascular systems.
- In body for an energetic release.
- Raises blood glucose levels.
Benschopp et al., (1996)
What study helps to illustrate the release of epinephrine and norepinephrine?
Topic: Stress Responses in Parachute Jumpers
Study Details: Measured epinephrine and norepinephrine levels at baseline, jump point, and post-jump.
Key Findings:
Stress responses are adaptive.
Epinephrine levels are lower on subsequent jumps compared to the first jump.
Conclusion: As the system learns it is not a survival situation, stress responses become less intense.
How does norepinephrine epinephrine link to fight or flight?
- Use the energy to confronting the stress.
- Or, use the energy to run away from it.
*stems from our evolutionary past
What are long-term stress responses?
Topic: Long-Term Stress Responses
Stress Process:
Epinephrine Release: Initial response to stressor.
CRH Release: Body releases Corticotropin-Releasing Hormone (CRH).
ACTH Stimulation: CRH triggers Adrenocorticotropic Hormone (ACTH) release from pituitary gland.
Cortisol Production: ACTH travels to adrenal glands and stimulates cortisol (glucocorticoids) production.
**Outcome: **Body manages long-term stress responses through this hormonal pathway.
What is the HXP Axis?
- Topic: HXP Axis
- Definition: The hypothalamic-pituitary-gonadal (HPG) axis is a set of interactions between the hypothalamus, pituitary gland, and gonads (ovaries/testes).
-
Functions:
- Reproduction: Regulates sexual development and reproductive processes.
- Hormonal Control: Oversees release of sex hormones like testosterone and estrogen.
-
Process:
- Hypothalamus: Releases gonadotropin-releasing hormone (GnRH).
- Pituitary: GnRH prompts pituitary to release LH and FSH.
- Gonads: LH and FSH stimulate gonads to produce sex hormones.
- Outcome: Crucial for sexual maturation, fertility, and reproductive health.
What are the two different effects of stress?
- Acute stress response adaptions.
- Pathological state assocaited with chronic stress.
List some examples of acute stress response adapations:
- Shift from energy store to energy use.
- Increased oxygen intake.
- Decreased pain perception.
List some examples of pathological state assocaited with chronic stress:
- Fatigue.
- Loss of libido.
- Impaired disease resitance; cancer.
Activational and Organisational effects:
Effects:
Activational: Glucocorticoids influence brain function and behavior in response to stress.
Organizational: During critical development periods, high steroid levels can permanently alter stress coping ability.
Outcome: Irreversible changes in stress response can result from elevated glucocorticoid exposure during development.
In rats:
Study to display prenatal stress:
Topic: Prenatal Stress and HPA Axis in Offspring
Effects:
Permanent Change: Stressing a pregnant rat permanently alters the HPA axis of its offspring.
Normal Response: Typical stress response involves a sharp peak of cortisol followed by a rapid decline.
Blunted Response: Offspring of prenatally stressed rats show a muted cortisol response to stress.
**Outcome: **Prenatal stress can lead to long-term changes in stress regulation in offspring.
In humans
Study to display prenatal stress (Weinstock., 1997):
- Women stressed in pregnancy are more likely to give birth to smaller babies.
- Reduced birth weight: growth hormones were suppressed because of cortisol.
- Developmental delays for children.
In rats
Study to display neonatal stress (Liu et al., 1997):
- Early stressful experience can positvely influence rats.
- Presenting rats after birth with mild stress **(separation from mother) were better able to cope with stressors as adults. **
In humans
Study to display neonatal stress (Gunnar et al., 2001):
Topic: Adoption Age and Cortisol Levels
Study Comparison:
Control: Canadian-born children.
Adopted at 8 Months: Showed cortisol levels similar to Canadian children.
Adopted After 8 Months: Strong correlation with higher cortisol levels (should be low).
**Key Insight: **Adoption at 8 months appears to be a critical window for normal cortisol regulation.
Stress and coping….
- There is a bi-directional relationship.
**- Stress affects behaviour, but behaviour can also affect stress responses **
What 4 ways can stress be coped with?
- Control
- Predictability
- Outlets for dealing with frustration
- Habituation
Stress and coping:
Control (Weiss., 1968)
Topic: Control and Stress Levels in Rats
Experiment:
**Setup: **Rats placed in containers with mild electric shocks; expected both to be equally stressed.
**Control Rat: **Given a lever to turn off the shock, exhibited lower stress levels.
**Key Insight: **Having control over a stressor can significantly reduce stress levels.
Stress and coping:
Predictibilty (Sapolsky., 1992):
Topic: Warning Signal and Stress in Rats
Experiment:
**Setup: **Rats placed in boxes with mild shocks.
Warning Signal: Rats given a light signal to indicate an upcoming shock.
**Results: **Rats with the warning signal did not develop gastric ulcers, unlike rats without the warning.
Key Insight: Warning signals can mitigate stress effects, such as preventing gastric ulcers.
