The Stress Response
The Brain is the master orchestrator of the Stress Response- coordinating a survival response via the Hypothalamus (at the base of the brain), Pituitary gland (situated in the brain in close proximity to the hypothalamus) and the Circulatory system disseminating hormone messages throughout the body.
As we experience or even think about something stressful the brain triggers a cascade of chemical reactions in the body by secreting a series of releasing agents.
The Sympathetic Nervous System releases Adrenalin (epinephrine) and Noradrenalin (nor epinephrine), which are very fast acting, working within seconds. They instantly prepare the body to run, fight or freeze by causing;
Increased heartbeat and blood pressure
Increased blood flow to peripheral muscles
Increased blood clotting rate
Release of sugar into the blood
Increased breathing rate
Increased alertness of the senses
Increased sweating
Inhibited digestion
This activity will be backed up within minutes or over hours by Glucocorticoids released by the adrenal gland (above the kidney). Glucocorticoids have similar effects to adrenaline and nor adrenalin and work with them to produce the stress response.
The brain and Pituitary gland will also secrete morphine like substances called endorphins and encephalin which initially blunt pain perception.
Reproductive hormones such as oestrogen, progesterone and testosterone are inhibited, as are growth hormones.
As a knock on effect to this strenuous use of the body’s resources and particularly if they continue over time, other chemical changes occur causing mood and behavioural changes
IL6 – interleukin gives a decrease in immune response leaving us more vulnerable to infection
Nerve Growth Factor (NGF) is released – which can help with injury repair, but where no injury is present, stimulates growth of nerve fibres within the sympathetic nervous system and therefore makes our stress response more sensitive – a vicious circle.
Increase in concentrations of the chemical Glutamate in the spinal cord which allows the passage of more pain messages. It is therefore important not to eat or drink extra Glutamate at times of stress – often present as a flavour enhancer in fast food and also present in red wine.
Decrease in the production of Oxytocin the chemical which stimulates us to bond with others. Stress often leads to feelings of isolation and relationship difficulties
Decrease in production of Serotonin and Melatonin which are important ‘feel good’ chemicals modulating mood and important in a healthy sleep/wake cycle. Serotonin is an important messenger chemical in the gut controlling the waves of muscle contraction that allow the normal transit of food through the digestive tract. Serotonin is also linked disruption of pain perception and change in eating patterns.
