STRESS

Biological Psychology Miss Bird

Stress and illness

Immune system Psychiatric conditions Cardiovascular disorders

Stress and illness is broken down into 3 sections. In the exam if the Q asks for stress-related illness you can write about any of the 3 sections. However the examiner may be specific and ask for just the immune system so make sure you read the question carefully.

Stress-related illness: The immune system

Pollack (1988) - link between stress and illness. Evans et al (2000) – stress is associated with dysfunction of the immune system.

Reminder 1.

SAM – damage to lining of the blood vessels (heart disease - CVDs).

2.

PAS – increased cortisol levels, suppresses/weakens the immune system.

What is the immune system?

    Main function is to protect the body from infection. It consists of a system of cells which fight against intruders in the body.

It defends the body against bacteria, toxins, viruses and parasites.

These are known as antigens.

2. If an antigen enters your body, the immune system attempts to detect and eliminate it before it stays there and reproduces.

1. It creates a barrier that prevents antigens from entering your body.

How does the immune system work?

3. If the antigen starts to reproduce, the immune system is responsible for destroying it.

Components of the immune system

Lymph nodes Thymus Spleen Bone marrow Lymphatic tissue of the intestine

Cells of the immune system

LEUCOCYTES

     White blood cells.

Bone marrow. Specific type in immune response = lymphocytes. Type T and B cells (thymus and bone) detect and destroy antigens.

Natural killer (NK)cells defend against infection.

Cells of the immune system

ANTIBODIES

  A specific B cell is tuned to a specific antigen.

When that antigen is present in the body the B cell produces millions of specialised immune proteins to destroy it.

Cells of the immune system

MACROPHAGES

  These pick up and ingest foreign materials. They give antigens to other cells in the immune system to destroy them (B and T cells).

Two types of immunity

Th1 immunity

  Fights infection aggressively.

Active during the night.

Th2 immunity

   Second line of defence.

Specialised immunity in form of antigens.

Active during the day.

Two types of immunity

    These responses are counter-regulatory – one works during the day and one works during the night.

When one branch is active it produces chemicals called cytokines that block the action of the other branch.

This ensures that the body has a balance between the two types of immune response with Th2 active during the day and Th1 active during the night.

Stress can influence the balance between each branch of immunity.

Research into stress and immune system functioning

 Most studies of the relationship between stress and immune system functioning have focused on acute (short-term) stressors and have found a decrease in immune cell function.  However other research has focused on the effect of chronic (long-term) stressors and also found a decrease in immune system functioning (decrease in white blood cell functioning).

Independent task

 Read the 4 studies on stress and immune system functioning in your booklet, including the key study by Kiecolt-Glaser et al (1984).  Write down the key points (APFCE) of each study in the table on your worksheet.  You have 15 minutes.

Independent task

Complete the fill-in-the-gap exercise on the evaluation into stress and the immune system.

Use the words provided at the bottom of the page.

Exam focus (plenary)

    Answer the past-exam question on stress and the immune system.

You have 5 minutes. It is worth 4 marks.

This is to be done in silence.

Assessment

During week 2/3 of the spring term you will have your first assessment on the stress topic.

This will be a 12-mark essay Q on stress and the immune system.

12X2 – Friday 16 th January P2 single lesson.

12Z1 – Tuesday 20 th January P4 single lesson.