This system acts like an army, identifying and killing any intruders to the body. It contains cells distributed throughout the body to fight diseases. These cells are called white blood cells (leucocytes) which identify and destroy foreign bodies called antigens. The existence of antigens however leads to the production of antibodies. For example, if u have had measles before then your body will have produced antibodies as a result of the initial infection and these will help the leukocytes fight off any next measles infection. This implies that if u had measles before, you wouldn’t catch it again because of the presence of the antibodies in your body produced when u had measles. However, if u haven’t had measles before, you can get vaccinated to prevent you from having it in the future. Vaccination is when you are injected with a mild dose of disease so that your body can produce antibodies.
There are several kinds of white blood cells within the immune system such as T cells which destroys invaders, T-helper cells which increases immunological activity, B cells and natural killer cells which are involved in the fight against both viruses and tumours.
* Kiecolt - Glaser et at. (1984) carried out a study oh human responses to stress by using a naturally occurring situation - examinations. This involved blood samples from 75 voluntary medical students (49 males and 26 females). The samples were taken one month before their final examinations (the baseline sample) and again on the first of their final examination, after the students had completes two of their exams wherein the students’ stress levels should be at their peak. The students were also assessed using behavioural measures. They were given questionnaires to assess psychiatric symptoms, loneliness and life events.
After this study Kiecolt - Glaser et al ended with two key findings; one was that stress was associated with a lowered immune response in humans. The second was that there were a number of different sources of stress and factors that moderate it.
Psychoneuroimmunology (PNI)
- The field of research that investigates the link between stress and other psychological states.
- Schliefer et al. (1983) looked at functioning of the immune system in the husbands of women who died from breast cancer. The husbands’ immune system functioned less after their wives had died than before, showing the impact of bereavement on the immune system.
The endocrine system and immunosuppression
It is possible that the link between stress and illness is due to the effects of endorphins. They are biochemical substances that are like opium and are released at times of pain or anxiety however, they also suppress the activity of the immune system. When a person is under stress their endorphins are ready to help cope with any pain, but at the same time the endorphins reduces the body’s immune system.
However, the evidences which suggests that stress can directly produce changes in the immune system and can develop various physical illnesses are said to be not conclusive. First reason for this is that the functioning of the immune system in most stressed individuals is actually within the normal range. Another reason is that the immune system is very complex, and so the quality of an individual’s immune system is hard to access.
Indirect effects of stress on the immune system: Lifestyle
Stress may cause illness indirectly through aspects of a person’s lifestyle, such as alcohol consumption, smoking. In technical terms, stressed individuals may be more likely to expose themselves to pathogens. For example, adults are more likely to resume smoking having given up when they experienced a high level of stress in their lives ( Carey et al, 1993 ). Increased in alcohol consumption is caused by anxiety, fear, or depression and is used to reduce the level of tension.
The effects of stress in the form of negative life events was tested by Brown 1991. He compared students who were high in physical fitness and those in low physical fitness. The end result was that stress almost trebled the number of visits by the unfit students, but had little effect on visits made by those who were physically fit.
