Textbook Notes (280,000)
CA (170,000)
U Windsor (800)
46 (100)
Brown (10)
Chapter

46-333 Chapter Notes -Coronary Artery Disease, Occupational Stress, Natural Killer Cell


Department
Psychology
Course Code
PSYC 3330
Professor
Brown

Page:
of 36
Section 1 Two bodily responses to Stress:
S.A.M (Sympathetic Adreno-medullary Pathway)
This is the acute (immediate) response to stress (it uses electrical signals). Higher brain areas (Cortex)
detect and perceive something as a stressor, triggering the Hypothalamus, which in turn activates the
Sympathetic branch of the Autonomic nervous system, stimulating the Adrenal Medulla, producing
two hormones, Adrenaline and Noradrenaline, which cause the Fight or Flight response, which causes
bodily changes and has evolved for survival.
Bodily changes may include: an increase in heart rate (to carry around oxygen around the body quicker); an
increase in blood pressure (veins and arteries narrow so blood pumps faster); an increase in muscle tension
(which increases reaction time) and the dilation of pupils (helps one to be more aware of one’s surroundings).
H.P.A (Hypothalamic Pituitary Adrenal Axis)
This is the chronic (slow, long-term) response to stress. Higher brain areas (Cortex) detect and
perceive something as a stressor, triggering the Hypothalamus, which in turn release the hormone
CRF, which activates the Pituitary gland in the brain, releasing the hormone A.C.T.H, which activates
in the Adrenal Cortex this releases corticosteroids (e.g. cortisol) that cause the liver to release
glucogen (fats and sugar), which provide continued energy for the Fight or Flight response. In the
long term, corticosteroids can suppress the immune system.
How stress can affect illness:
Direct Effect
This is where stress directly causes an illness of the malfunction of the immune system. For example,
coronary heart disease has been shown to the have a link with the S.A.M response. It is caused by
increased heart rate and narrowed arteries (which are results of the Fight or Flight response,
brought about by the S.AM response) which cause increased fats and sugars blocking arteries, as
well as putting more pressure on the heart. High blood pressure and strokes are also linked to
stress.
Indirect Effect
This is where stress may make people more
vulnerable
to illness, as it may weaken the immune
system. Some people inherit a weak immune system and stress may make them even worse. Lifestyle
also affects the immune system and stress may cause such behaviours to increase. For example,
when one is stressed they may turn to drinking, drug and tobacco use, etc or change their sleeping
and eating habits or even going out all night partying. All these things can suppress the immune
system if done frequently. The relationship between stress and illness may be seen as very complex.
Research into stress and illness
Keicolt-Glaser et al (medical student study)
The aim of this study was to see if exam stress may affect the functioning of the immune system; it
was therefore a natural experiment, using a volunteer sample (which consisted of 75 first-year
medical students) and repeated measures. The procedure was as follows: blood samples were taken
of all the students one month before their exams (this was defined as a low stress period) and again
on the first day of their exams (this was defined as a high stress period). These blood samples
measured the participants’ immune functioning by counting the number of leucocytes (natural killer
cells & T cells) - if there was a high number, this meant a strong immune system. If they were low,
it meant the opposite. It was found that in the high stress period, the number of killer cells and T
cells were low, whilst in the low stress period, the number was high. There was, therefore, a negative
correlation between exam stress and immune functioning. It was concluded that there was indeed a
link between the two exam stress is associated with immunosuppression. However, stress is only
one factor that may affect the immune system.
A weakness of this study is the sample they were all first year medical students this is not
representative as the group cannot be generalised to other students, ages or groups. Also, they are
volunteers the sample is therefore biased as volunteers are ‘unusual’ or ‘extra-motivated’ it lacks
population validity, which in turn leads to an inability to generalise. However, Keicolt-Glaser has
carried out research using Alzheimer’s carers and married couples and found similar results this
makes the findings of this study more reliable and is in fact can be generalised to slightly more
groups.
It is also a natural experiment; therefore the study has high ecological validity and mundane realism
as the situation was real and was not manipulated by the experimenter. As it is such a natural
situation, there is also a significantly smaller chance of participants responding to demand
characteristics; it is unlikely that they were able to consciously affect their blood test. However,
this type of experiment essentially means that no extraneous variables that could potentially affect
the results were controlled therefore, we cannot be sure that the level of stress is what affected
immune functioning alone. There are many other factors, including lifestyle and genetics, which were
not considered this questions the validity of the results. It is also impossible to replicate the
experiment and therefore we cannot see if the results found in this study are reliable.
The findings of this experiment were merely a correlation, therefore it only proves that there may be
a relationship between the two co-variables this is positive in the sense that it avoids ethical issues
as no variables are being manipulated, merely measured the ‚participants were protected from
harm‛ as no stress was deliberately caused. However, correlations mean that it can never be
proved that the exam stress caused the change in immune functioning due to the other
(confounding) variables that have not been controlled or taken into account such as medical
conditions and lifestyle (such as sleep problems and eating habits etc.).
The method used to measure immune functioning has been deemed as inadequate the immune
system is complex - T-cells and natural killer cells are only one aspect it is therefore too simplistic
and difficult to know whether the immune system is weak from this alone different parts may be
stronger to compensate for it, such as fast wound healing.
Keicolt-Glaser (Alzheimer’s carers and married couples)
She tested the impact that conflict between spouses could have on the length of time wounds took
to heal. It was found that blister wounds on the arms of husbands and wives healed more slowly
after a conflicting discussion or argument this was seen more in women than in men.
She also found that carers of Alzheimer’s disease sufferers took significantly longer to heal minor
arm wounds. Looking after the relative or the patient (a major stressor) may have suppressed the
immune system which can be dangerous.
However, these studies use a very small and unrepresentative sample, therefore they lack population
validity and they cannot be generalised. They were also natural experiments, and therefore we
cannot prove cause and effect, nor see if the results are reliable as we cannot replicate them there
may be other factors genetics, the type of stress, personality, culture etc. that may cause the
findings.
Cohen et al (Common cold study)
This was a lab experiment and 394 volunteers were exposed to the cold virus. Their level of stress
was then assessed via a questionnaire. It was found that there was a positive correlation between
stress level and the likelihood of developing a cold.
However, questionnaires were used these may be unreliable as participants are liable to giving
socially desirable answers which therefore questions the validity of the results generated by the
questionnaire. Also, the findings were only a correlation, so it cannot be proved that stress caused
the cold as there are other variables that were not controlled. Volunteers were also used, so the
study is lacking in population validity and is not representative.
Marucha et al (dental students and biopsy study)
The effect that stress had on healing was tested on 11 dental student volunteers. They underwent a
small biopsy on the roof of their mouth at two occurrences; the first being at the beginning of their
summer holidays (defined as low stress) and the second six weeks before exams (defined as high
stress). The healing of the wound was monitored and recorded, using videos of the mouth. The rate
of reduction in wound size was measured at the two levels of stress. It was found that students were
40% slower to recover in the ‚high stress‛ period. This suggests that stress can affect how long it
takes a wound to heal as the immune system is suppressed.
However, this study uses a very small and unrepresentative sample, therefore it lacks population
validity and it cannot be generalised. They were also natural experiments, and therefore we
cannot prove cause and effect, nor see if the results are reliable as we cannot replicate them there
may be other factors genetics, the type of stress, personality, culture etc. that may cause the
findings.
Stressors Life Changes & Daily Hassles
Life Changes and research into it.
These are major changes or events in your life that tend to be rare or one-off’. They happen rarely
and would be considered quite ‚large‛; they require significant change, adjustment or transition and
to an individual this can cause stress. Examples include getting a divorce, a death of a relative or a
friend, redundancy or a pregnancy.
Dr. Holmes and Dr. Rahe noticed that the patients they treated had undergone both positive and
negative life events which all required transition, which would expend energy Holmes & Rahe
believed that this expenditure of energy is what is stressful and may affect health, causing illness.
The Social Readjustment Rating Scale (The SRRS) (Describe research into life changes and stress-
related illnesses)
Developed by Holmes & Rahe, this scale was designed to measure life changes as to how stressful
they are. It contains 43 life events which all have a score or (life change unit). Participants normally
have to ‚tick‛ all the events that have happened to them in the past year and add up the scores – if
the life change unit was above 150, it was predicted a 30% increase in the likelihood of developing a
stress-related illness if the life change was above 300, there was a 50% increase. Events included
‚Death of a Spouse (100), Divorce (73), Marriage (50), Christmas (12), Change in financial state (50)
and Jail (63)‛.
However, individual differences are not taken into account at all; the scores are practically arbitrary
and how stressful an event is may be subjective. For example, making an ‚Outstanding Achievement‛
was given a score of 25, yet many would not find this stressful at all. Just the opposite in fact, they
may find it elating. However, the scale insists this is stress anyway it cannot be applied to all
people.
The scale is also vague; it is unclear whether many of the events are positive or negative mostly it
just states ‚a change‛- for example, ‚a change in financial state‛ may be positive or negative.
Evidence suggests that only change that is undesired, unscheduled and uncontrollable is stressful,
but this is not taken into account.