Health and Stress

Question 1

What did Selye (1950) propose about stress?

Answer 1

Stress response has a dual nature. Two main effects.

1. Short-term produce adaptive changes which help the animal respond to the stressor.
2. Long-term - Changes which negatively impact health.

Question 2

Describe the first system of the stress reponse

Answer 2

Hypothalamic pituitary adrenal (HPA) system

• Hypotalamus produces CRF
• Anterior pituitary gland - CRF triggers the release of ACTH
• ACTH stimulates the adrenal cortex to produce cortisol and corticosteriods
• Corticosteroid - hormone releases stored glucose from the liver for energy + controls swelling after injury.
• Measure stress by looking at glucocorticoids.

E.g. trier social stress test Kirschbaum et al. (1993).

• Baseline
• Give 5-minute speech as job application and spend 5 minutes counting back from 1,022.
• Saliva and blood samples collected. Increased levels of substances known to indicate the activation of HPAA
• Salivary cortisol peaks 10 minutes later, hGH peaks 40 minutes later. Serum cortisol, prolactin and ACTH peak immediately after test

Success - Gives objective measure of stress

Question 3

Describe the second system of the stress response

Answer 3

Sympathetic Nervous System

• System important because it becomes activated by stressors.
• When activated, epinephrine and norepinephrine are released from the adrenal medulla which prepares the body for a flight or fight response.
• As a result, there is increased blood flow to muscles, pupil dilation and glycogenesis. Need more energy, so provides us with this.
• After threat is gone, can take 20-60 minutes for body to return to normal. Good for evolution.
• Priming body for action means that you can effectively cope with threat. Critical role in surival, more likely to survive.

Question 4

Describe the case of gastric ulcers in response to stress

Answer 4

Lesions to lining of the stomach which happen to those who encounter stress often.

Are psychosomatic - psychological factors play a role.

However, changed when discovered that they caused by baceria.

Blaster (1996) - Stress mediates the susceptibility of the stomach wlal to be damaged by H.pylori causing ulcers.

Other research suggests that it is not enough to produce the disorder as some health subjects have signs of it (75%). Psychological treatments reduce the signs of the infection. Stress increases susceptibility.

Question 5

How does the immune system respond to stress?

Answer 5

Innate Immune System

• First to react
• Triggered when toll-like recpetors bind to molecules on the surface of the pathogens.
• Inflammation one of the first respinses to invasion of pathogens. Triggered by release of chemicals from damaged cells. Inflammation increases blood flow to sute carrying important cells called phagocytes.
• Cytokines important - attract lecukocytes and other phagocytes to infected area. Promote healing of damaged tissue.

Adapative Immune System

• Evolved more recently
• Slower
• Reacts against specific antigens
• Has a memory - once reacted against pathogen, reacts effecitvely against same in the future. Gives vaccinations preventative effect.
• Main cells are specialised leukocytes called lymphocytes which are produced in bone narrow.
• Two major classes

B-Cells - Anti-body mediated immunity happening in body fluids, outside cells.

T-Cells - Cell mediated immunity to attack cells that are compromised, inside cells.

Question 6

What are the effects of stress on the immune system?

Answer 6

Seen as disruptive, however this is not consistent with evolution as every organism encounter stress, important.

During acute stres, increased chance of skin-lesion interacting with pathogens. Why the immune system boosts during acute episodes of stress, cytokines released.

Segerstrom & Miller (2004) - Effects of stress on immune function depend on the kind of stress.

Acute stress can improve immune function to innate immune system.

Chronic stress negatively impacts adaptive immune system, no idea when will end. Suppression of the immune system, functional.

Question 7

How can exercise help to combat stress?

Answer 7

Exercise is an acute stressor which produces free-radicals that contriubute to oxidative stress.

Steptoe and Butler (1996)

• Habitual vigorous exercise associated with reduced emotional distress and positive emotional wellbeing.

Stewart et al. (1994) - Self-reported time exercising predicated range of positive health outcomes 2 years later. Reduced anxiety, depression and subjective wellbeing.

Cramer et al. (1990) - Effects of exercise over 15 weeks. Increased wellbeing, however anxiety decreased then began to increase again.

Question 8

How can socialising help to combat stress?

Answer 8

Cohen and Willis (1985) - Stress buffering hypothesis. The presence of a social support system helps shield an individual from the negative impact of stressful events.

Social baseline theory(Coan, 2008). Social proximity is a baseline condition for adaptive and healthy human functioning. Humans expect to live in groups. Out-sourcing some of our regulatory needs to close others is our expected state of being.

Beckes andCoan (2011) - Support theory. Human brain designed to assume it is embedded in a social network characterised by familiarity, joint attention, shared goals. Social proximity inhibits release of stress hormones and promotes good health. Social rejection a source of stress.

Jakubiak and Feeney (2016) - Social proxmity studied by looking at interpersonal touch. Two mechanisms suggested. Relational-cognitive pathway = feelings of security, support, trust. Neurobiological pathway = increase in oxytocin, reduced hormonal and phyiological reactivity to stressors.

Coan et al. (2016) - Handholding reduced neural response to a stressor. Spouse handholding associated with least unpleasantness.

Masters et al. (2009) - Reduced pain when looking at partner compared to stranger and when holding hand.

Question 9

What are the effects of loneliness on stress?

Answer 9

Social proximity is important for survival and stress reduction. Suggested that loneliness is an aversive state that motivates us to seek social interaction to promote our survival and health. Stigmatised.

Doane & Adam (2010) - Loneliness associated with increased cortisol awakening response next morning.

Cacioppo et al. (2015) - Socially isolated have increased activity of the HPA axis.

Don’t have access to stress-buffering influences of social interaction.

Holt-Lunstad, Smith and Layton (2010) - Increased numbs of social relationships led to decrease in risk of mortality.

Question 10

Wolf et al. (2007) Stress and Immune Function

Answer 10

Stress in mothers can aggregate asthamtic symptoms in children.

Asthma in children increases measures of stress in mothers.

Question 11

Does stress increase the susceptibility to disease?

Answer 11

No because..

• Immune system has many redudant components, disruption to one of them may have little effect.
• Stress produced effects may be short-lived
• Declines in some aspects of immune function may induce compensatory increases in others.
• Difficult to study, only correlational studies.

Cohen et al. (1991) - Stress questionaires then injection of virus or saline. Those who scored higher on stress scales developed colds.

Question 12

What are the effects of stress on the hippocampus?

Answer 12

• Area particularly prone to effects of stress. Might be due to inc number of glucorticoid receptors

Stress can..

• Reduce dendritic branching in hippocampus
• Reduce adult neurogenesis
• Modify structure of hippocampal synapses

Can be induced by corticosterone and blocked by adrenalectomy.

Question 13

Explain the early effects of stress on development

Answer 13

Liu et al. (1997)

• Handled rat pups groomed more by mothers.
• Unhandled rats which recieve a lot of grooming from mothers showed less glucocorticoid release than handled pups.
• When mothers are fearful, show poor grooming and this results in the rat showing this as a parent themselves.