The Immune System
Structures and mechanisms that allow the body to resist and fight off infection by antigens:
- Bacteria
- Viruses
Stress reduces the effectiveness of the immune system ability to fight antigens.
The immune system contains cells known as lymphocytes.
There are two types of lymphocytes:
B cells- produce antibodies which are released into the fluid surrounding the body’s cells to destroy the invading viruses and bacteria.
T cells (see picture opposite) - if the invader gets inside a cell, these (T cells) lock on to the infected cell, multiply and destroy it.
Stress and Immune Function
Short term suppression of the immune system is not dangerous.
However, chronic suppression leaves the body vulnerable to infection and disease.
A current example of this is AIDS - Acquired immune deficiency syndrome.
Here the immune system is suppressed leaving the vulnerable to illness.
Stress would just lead to frequent illness and infections.
Stress responses increase strain upon circulatory system due to increased heart rate etc.
This may increase a person’s risk of developing disorders of the heart and circulation e.g. coronary heart disease
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 gastric ulcers The executive monkey study by Brady seems to support this theory.
Kiecolt-Glaser et al., (1995)
Aim: To investigate whether stress of important examinations has an effect on the functioning of the immune system
Procedure:
This was a natural experiment using 75 medical students
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 exam.
Conclusion: Stress (of the exam) reduced the effectiveness of the immune system.