Stress Part 2 Stress-related illness and the immune system. News reader idea!

Syllabus Stress-related illness and the immune system

Natural Immunity White blood cells (leukocytes). These non- specifically attack and ingest (absorb) invading pathogens such as virus and bacteria. These include macrophages, phagocytes and natural killer cells. – Quicker

Specific Immunity Lymphocytes. Recognise the invading pathogens and produce specific antibodies to destroy them. – Energy intensive – Takes time to develop

Consequences of the stress response Cardiovascular problems – if the blood pressure and heart rate are high all the time, the vessels would constantly be used and some parts may wear off after a while. This could cause cardiovascular problems as it could make you more likely to get a heart attack. Immunosuppression – when the ‘fight or flight’ response is activated, more adrenaline is released which allows more oxygen and glucose to travel to the muscles and brain, however this means that less glucose and oxygen will travel to the parts of the body that would not be involved in dealing with acute stress such as the immune system and digestive system. So the immune system will be suppressed and the person will be more likely to be ill. Stress: Occurs when the demands to do something is higher than the ability to cope with it.

Stress related illness and the immune system Kiecolt-Glaser et al (1984) did a natural experiment to investigate the effect of acute stress on illness levels. They used students as participants and measured their immune system activity a month before their examinations and measured it again during the examinations. They found that immune system activity decreased during the exams, presumably because there is more acute stress.

Stress related illness and the immune system Evans et al – showed how acute stress could boost immune system activity. They conducted an experiment which used students as participants; the students were given a small talk to give to other students which is a mild acute stressor. The amount of slgA (an antibody) during the time of the talk was higher than the amount of slgA before they had to give the talk.

Stress related illness and the immune system Kiecolt-Glaser et al (2005) – showed how chronic stressors negatively affect immune system activity. They did a laboratory experiment which used hostile couples and less hostile couples as participants. All of the couples were given blister wounds and the time it took for the wounds to heal was a measure of how much the immune system activity was. It took longer for the more hostile couples to heal their blister wound than the less hostile couples. This shows that chronic stressors reduce immune system activity.

Stress related illness and the immune system Kiecolt-Glaser et al showed that in general, the immune system of women are more affected by marital conflict than the immune system of men.

Stress related illness and the immune system Segerstrom and Miller did a meta-analysis and found that acute stress boosts immune system activity in general while chronic stress generally reduces immune system activity. Look at article from Daily Mail. Look at paper:

Stress and Illness Stress responses have an effect on digestive system. During stress digestion is inhibited. After stress digestive activity increases. This may affect the health of digestive system and cause ulcers. Adrenaline released during a stress response may also cause ulcers. Stress responses increase strain upon circulatory system due to increased heart rate etc. Stress can also affect the immune system by raising blood pressure.

Stress and Illness Hypertension (consistently raised blood pressure over several weeks) is a major risk factor in coronary heart disease (CHD) However, CHD may be caused by eating too much salt, drinking too much coffee or alcohol. Stress also produces an increase in blood cholesterol levels, through the action of adrenaline and noradrenaline on the release of free fatty acids. This produces a clumping together of cholesterol particles, leading to clots in the blood and in the artery walls and occlusion of the arteries. In turn, raised heart rate is related to a more rapid build-up of cholesterol on artery walls. High blood pressure results in small lesions on the artery walls, and cholesterol tends to get trapped in these lesions (Holmes, 1994).

indirect effect Stress can also have an indirect effect on illness as it is associated with all manner of bad habits (coping strategies), for example smoking, drinking alcohol to excess, poor diet due to lack of time, lack of exercise for the same reason, lack of sleep etc. All of these are likely to have an adverse effect on a person’s health so could cause some of the ill-effects attributed to stress per se.

Kiecolt-Glaser et al., (1984) Aim: To investigate whether stress of important examinations has an effect on the functioning of the immune system Procedure: This was a natural experiment. The researchers took blood samples from 75 first year medical students (49 males and 26 females), all of whom were volunteers. Blood samples were taken: (a) one month before their final examinations (relatively low stress), and (b) during the examinations (high stress) Immune functioning was assessed by measuring T cell activity in the blood samples. The students were also given questionnaires to assess psychological variables such as life events and loneliness.

Findings: The blood sample taken from the first group (before the exam) contained more t-cells compared with blood samples taken during the exams.t-cells The volunteers were also assessed using behavioural measures. On both occasions they were given questionnaires to assess psychiatric symptoms, loneliness and life events. This was because there are theories which suggest that all 3 are associated with increased levels of stress. Kiecolt-Glaser et al found that immune responses were especially weak in those students who reported feeling most lonely, as well as those who were experiencing other stressful life events and psychiatric symptoms such as depression or anxiety.

Conclusion: Stress (of the exam) reduced the effectiveness of the immune system. Evaluation: Difficult to unravel the relationship for certain. Does stress cause illness or does being ill make you more prone to stress? Also many of the studies do not take into account for the other factors which affect people’s lives. These can be drugs, alcohol, caffeine, nicotine, general health, diet, physical activity, sleep patterns, age and medication. Although many studies try to control these factors it is very unlikely to gain complete control.

Important There is a mechanism linking stress to the down regulation of the immune system is the action of corticosteroids in reducing lymphocyte (specific immunity) production and shrinking the thymus gland.

T cell: A type of white blood cell that is of key importance to the immune system and is at the core of adaptive immunity, the system that tailors the body's immune response to specific pathogens. The T cells are like soldiers who search out and destroy the targeted invaders. T cell are also known as T lymphocytes. The "T" stands for "thymus" -- the organ in which these cells mature. As opposed to B cells which mature in the bone marrow.