STRESS

1. HPA System

1.1. 1. Chronic Stress are perceived by the Hypothalamus. 2.Higher brain center (cortex) activates the hypothalamus. 3. Hypothalamus releases CRF – which travels through the blood to the pituitary gland. 4. Pituitary releases ACTH – which travels to the adrenal cortex. 5. Adrenal cortex releases corticosteroids (such as cortisol) into the bloodstream. 6. These hormones have an effect on the body. Such as an increase in blood pressure, sweating. increased production of glucose from glycogen in the liver, and weakens the immune system.

2. SAM system

2.1. 1. Acute stress (Immediate acting pathway) 2.Hypothalamus activates the SNS (sympathetic nervous system). 3 Activation of the SNS causes bodily arousal. (Rapid increase in heart rate, breathing rate, sweating, butterflies in the stomach,) 4. SNS also activates the adrenal medulla. 5. The adrenal medulla releases adrenaline and non adrenaline into the bloodstream. 6. These hormones have an effect on the body. 7. Prepares the body for "Fight or flight response".

3. GAS System

3.1. Alarm stage 1. The brain perceives the stressor and prepares the body for "Fight or flight response". 2. This is done by the hypothalamic-pituitary-adrenal axis as it releases ACTH triggering the release of adrenaline. 3. This causes heart rate and oxygen intake increases, so does the breathing rate. It stimulates the liver to release more glucose, and dilates the pupils to improve visual sensitivity, making the body prepared to act immediately. (If danger passes- body returns to normal/ If danger continues- goes on the resistance stage)

3.2. Resistance stage 1. Attempt to go back to normal functioning of the body by trying to repair from the alarm stage as there are still high level of arousal/ adrenaline. 2. If the stress disappears then the body goes back to normal. 3. But, If stress continues steroids start to interfere with the immune response and we are less able to fight infection. 4.If another stressor occurs, our body start to become exhausted.

3.3. Exhaustion stage 1. This is when the energy in the body to fight the stressor has been depleted. 2. Chronic stressor is more likely to deplete all of a person's energy that had been stored, which may result to serious illnesses as immune system will leave us prone to infection.

4. Immune system

4.1. 1)Viruses/Bacteria/ Allergies = Antigen. 2)The main type of immune cells are white blood cells - there are 2 of them (lymphocytes and phagocytes) 3) Phagocyte surrounds and engulfs the virus. 4)B cells- antibodies which are released into the fluid surrounding the body’s cells to destroy the invading viruses and bacteria. 5)T cells - if the invader gets inside a cell, these (T cells) lock on to the infected cell, multiply and destroy it. 6) The cells are able to recognise the attacker from previous, therefore a future infection can be fought quicker.

5. Stress related illness

5.1. Kiecolt-Glaser et al (1984) 1) They investigated the relationship between stress and immune system in 75 medical students, who were preparing for important examinations. (They were looking if the T cells increased/ decreased with stress) 2) Blood sample were taken, where natural killer cell (T cell) was measured one month before, during and one month after the exams. 3) They found out that due to the stress condition (exam), the day of the exams, their T cells reduced, making them more prone to illness as they do not enough T cells to fight off virus.

6. By Leena Gurung