Stress and Immune Function: Psychology Study Notes

Stress and Immune Function

Immune System Overview

The immune system is a complex body system that protects against invading bacteria, viruses, and pathogens. It consists of various types of white blood cells, each with specialized roles in defending the body.

• Lymphocytes: A type of white blood cell crucial for immune responses. Major types include:

  • T Cells: Responsible for cell-mediated immunity, attacking infected cells directly.

  • B Cells: Produce antibodies that neutralize pathogens.

  • Natural Killer Cells: Destroy virus-infected cells and tumor cells.

Example: When a virus enters the body, B cells produce antibodies to target the virus, while T cells destroy infected cells.

Stress and Its Effects on the Immune System

Chronic stress can negatively impact immune function, making individuals more susceptible to illness. The body's response to stress involves the activation of the HPA axis (hypothalamic-pituitary-adrenal axis), which leads to the release of stress hormones such as cortisol.

• Activation of HPA axis: Increases cortisol levels, which suppresses lymphocyte production and activity.

• Suppression of lymphocytes: Reduces the body's ability to fight infections and diseases.

• Immune suppression: Chronic stress can lead to decreased immune function and increased vulnerability to illness.

Example: Students experiencing chronic academic stress may have lower lymphocyte counts, making them more prone to colds and infections.

Research Findings: Stress and Susceptibility to Illness

Studies have shown that individuals under chronic stress are more likely to develop illnesses. The provided bar graph illustrates the relationship between the number of stressors and the percentage of people who developed colds after exposure to a virus.

Number of Stressors	% Who Developed Colds
0	27%
1	34%
2	39%
3	45%
4+	50%

Interpretation: As the number of stressors increases, the likelihood of developing a cold also increases, demonstrating the suppressive effect of stress on immune function.

Example Question

Question: What part of the immune system is suppressed by the activation of the HPA axis?

• Correct Answer: Lymphocytes

Explanation: The activation of the HPA axis during stress leads to increased cortisol, which suppresses lymphocyte activity and production, weakening the immune response.

Additional info: The HPA axis is a central stress response system. Chronic activation can lead to long-term health consequences, including increased risk for infectious diseases and slower recovery from illness.