Give some examples of physical stressors
Injury, surgery, infection, shock, pain, exposure to cold, sustained exercise
Give some examples of emotional stressors/threats
Imprisonment, torture, exams
Which body systems are involved in stress?
Complex interaction between nervous system, endocrine system and immune system
What do the effects of stress depend on?
Duration and severity of the stressor
The effectiveness of any responses
What are the 3 stages of stress (the General Adaptation Syndrome)?
- Alarm reaction
- Resistance phase
- Exhaustion phase
Describe the alarm reaction in stress
Fight, flight or fight response
Physiological response to physical threat
Acute stress response
Describe the resistance phase of stress
Adapting to the stressor
Describe the exhaustion phase of stress
Occurs in severe, persistent stress
Responses are futile; systems fail
Pathological effects
What is the General Adaptation Syndrome?
A there-stage response that the body has to stress: alarm reaction, resistance phase, exhaustion phase
Which systems are involved in the alarm reaction (acute stress response)?
Neural: sympathetic nervous system
Hormonal: adrenal glands
Adrenaline (adrenal medulla)
Corticosteroids (adrenal cortex)
Describe the neural component of the alarm reaction
Sympathetic nervous system
- Increased cardiac output: increased heart rate, increased ventricular contractility
- Redistribution of cardiac output: increased flow to muscle, decreased flow to gut, kidney
- Metabolic effects: glycogen breakdown -> glucose release, mobilisation of fat stores -> release of free fatty acids
- Stimulation of adrenaline release
Describe the adrenaline hormonal component of the alarm reaction
Adrenaline is secreted by the adrenal medulla
Adrenaline release augments and prolongs the action of the sympathetic nerves: increased cardiac output, redistribution of cardiac output, metabolic effects
Decrease the corticosteroid hormonal component of the alarm reaction
Glucocorticoids are released from the adrenal cortex
Includes steroids such as cortisol
Cortisol is the main stress hormone
Its actions complement those of the sympathetic NS and adrenaline
May have harmful effects if secretion is persistently high
Decrease the actions of cortisol in the stress response
- Metabolic: increased energy production from glucose, amino acids and fats
Increased protein breakdown - Enhances the effects of adrenaline: ‘permissive’ effect
- Anti-inflammatory actions
- Immunosuppressive
Describe the effects cortisol has on the immune response
- Anti-inflammatory and immunosuppressant actions
- Can inhibit the release of prostaglandins and leukotrienes
- Inhibit macrophages and helper T cells
- Increased incidence of illness at times of stress
Describe corticosteroid therapy
- Some patients take corticosteroids as anti-inflammatory drugs (e.g. arthritis)
- Long-term corticosteroid therapy can disrupt normal control mechanisms
- The drug will suppress CRH and ACTH release, and the natural stress response is suppressed
Describe the HPA axis in the control of cortisol
- Hypothalamus releases corticotropin releasing hormone (CRH)
- CRH acts on anterior pituitary
- Anterior pituitary releases adrenocorticotropic hormone (ACTH)
- ACTH acts on the adrenal cortex
- Adrenal cortex releases cortisol
- Cortisol has negative feedback effect on release of CRH and ACTH
What is ‘stress analgesia’?
When pain is diminished by physical stress e.g. sports, battle
Due to release of endogenous opioids, peptides, enkephalins in the CNS
How can we assess stress?
Changes in heart rate and blood pressure
Give examples of stressors patients may experience at a visit to the dentist
- Stress depends on the severity of the treatment (extraction > scaling)
- Pain increases amount of stress
- Local anaesthesia is stressful
- Noise of dental instruments contributes to stress
- Masks and gowns add to stress
Describe the range of stress-induced changes to BP and HR
Systolic BP = +5-20 mm Hg
Diastolic BP = +4-8 mg Hg
HR = up to +20 bpm
When are the effects of stress greater in dentists?
When standing
With complex/difficult procedures
With anxious patients
What happens to the individual if the stressors continue to be present?
Either they cope - Adaptation phase
Or they don’t - Exhaustion phase
Describe how an individual adapts to the stressor (resistance phase)
With persistent exposure to stressor, the individual’s stress response diminishes
Stressor is no longer seen as a ‘threat’
The individual has become ‘resistant’ to the stressor
Generally happens if the individual’s responses are effective in removing the stressor (or its perceived threat)
