Stress Flashcards
What is a stressor?
A threatening/demanding event or situation
What is the stress response?
Physiological, psychological and behavioural changes
What 2 neuroendocrine systems are activated?
Sympathy-adrenergic system (SAS) and Hypothalamic-pituitary-adrenal axis (HPA)
What are features of the SAS?
rapid, short term response, mediated by catecholamines (adrenaline, noradrenaline)
What are features of the HPA?
longer term response, mediated by glucocorticoids (cortisol)
What communication does stress cause?
Bi-directional brain-body communication
What is the stress response also known as?
General Adaptation Syndrome
What are the 3 stages of GAS?
Alarm reaction, resistance stage and exhaustion stage
What happens in the alarm reaction stage?
Stressor is perceived by pituitary-adrenal system, SAS system prepares body for Fight or Flight, HPA system releases energy store
What happens in the resistance stage?
Body attempts to re-establish physiological balance, if stressor persists - stress hormones and arousal remains high
What happens in the exhaustion stage?
Prolonged stress eventually depletes resources and exhausts body’s defences and stress related illnesses develop
What physiological changes are associated with stress?
Increase blood pressure, rapid heart rate and rapid breathing
What does the SAS activate?
Brainstem nuclei, sympathetic nervous system and adrenal medulla
What releases adrenaline and noradrenaline into the blood?
Adrenal medualla
What does noradrenaline do?
Stimulates muscles, contraction redirects blood to essential organs and increases blood pressure
What is the effect of adrenaline?
- Raises heart rate
- Increases blood flow to muscles
- Reduces blood flow to skin and intestines
- Raises blood sugar
- Causes adipose tissue to release fat into blood
- Widens air passageways in lungs
- Dilates pupils
What is the effect of cortisol?
- Oxygen directed to brain
- Stimulates breakdown of fats
- Stimulates production of glucose
- Inhibits growth and reproduction
- Supresses immune system
- Contains inflammatory responses
- Enhances arousal, vigilance and cognition
What systematic stressors trigger a stress response?
- Nociceptors (pain)
- Inflammatory signals (infection)
- Stimulation of baroreceptors or osmoreceptors (blood pressure)
What neurogenic stressors trigger a stress response?
- Anticipatio/recognition of predators/competitors
- Dangers associated with novel environment
What happens with some species in terms of stress?
Interactions with conspecifics
What stressors can be difficult to avoid?
Job-related, financial worries, transport, transport, pandemic etc
What is Eustress?
Perturbation can be dealt with effectively, stress response quickly terminated once homeostasis restored
What is distress?
Chronic hypo-/hyperactivation of HPA axis, may be harmful and lead to abnormal behaviour
What are the characteristics of an individual challenged by a stressor?
- Genetic predisposition
- Past history/experience
- Age or stage of development
What is the Yerkes-Dodson law?
Arousal improved performance up to an optimal point, after this performance begins to decrease
What is released to dampen the SNS and HPA responses?
Oxytocin
When does Stress immunisation occur?
When exposure to mild stressors early in life builds greater resilience later on
