Lecture 7: The Psychobiology of Stress Flashcards
Why do we study stress?
Stress can effect psychological morbidity, physical disease, disease progression and performance.
How does stress get inside the body?
Something in the environment has changed and we need to respond to it. We see it as being stressful. Then activates 2 systems (Nervous and Endocrine) which interact with other systems (cardiovascular, digestive, immune and reproductive)
How many pathways are there?
Two
Where do the pathways originate and terminates?
Originate in Hypothalamus and terminate at the Adrenal Gland.
How do we activate the pathways?
When we interpret a stressor, we activate the hypothalamus which activates the 2 pathways
What is the Sympathetic Adrenal Medullary Axis?
The Hypothalamus sends a signal through the Nervous System to the inside of the Adrenal Medulla
What is the second process?
The Hypothalamus stimulates the Pituitary Gland which stimulates the Adrenal Cortex. This process is slower as involves the secretion of hormones.
What hormone is secreted by the Hypothalamus in the 2nd process?
Corticotropin releasing hormone and this stimulates the Pituitary Gland
What hormone is released by the Pituitary Gland?
Adrenocorticotropic hormone and this stimulates the Adrenal Cortex
(SAMA) What hormone is released from the Adrenal Medulla?
Adrenaline and Noradrenaline
What are the roles of Noradrenaline and Adrenaline?
Increased HR and BP, redirection of blood muscles/organs
Initiates the Fight or Flight response
What happens when you get a fright?
You release adrenaline and noradrenaline and start to initiate the pathways including the Pituitary Gland. Involves the secretion of hormones
What are the roles of Cortisol?
Maintenance of Fight or Flight response. Increased:
- Sensitivity if cells to adrenaline and noradrenaline
- Blood sugar levels
- Mental Alertness
What else does Cortisol do?
Switches off long term processes so resources can be directed to immediate threat
What are the long term processes?
Immune system Growth and Repair Digestion Reproduction Regulation of Sleep patterns
Why are stress responses essential in short term?
Mobilisation of resources to deal with immediate threat. Temporary increases on mental and physical abilities. Redirection of resources from long term processes to threat
Why are stress responses harmful in the long term?
If the stress doesn’t go away then long term processes are switched off
What can chronic stress lead to?
- Increased risk of ill health (immune)
- Inability to heal wounds (G+R)
- Increased risk of peptic ulcers (Digestion)
- Fertility problems (Reproduction)
- Development of insomnia (Sleep)
How to measure stress hormones?
Adrenaline and Noradrenaline - draw blood
Can measure hr, bp and skin (sweat)
Cortisol can be measured by a salivary swab
What is the Circadian (24hr) Cortisol Profile?
In first half of sleep cortisol is quite low
2nd half it begins to increase
When you wake in morning cortisol is high and begins to decrease during day
Reaches lowest when go to bed
What is the Diurnal (daytime) Cortisol Profile?
Usually measure cortisol in daytime - awake so can do swab
30-45 mins after you wake get a serge in cortisol - called the Cortisol Awakening Response (CAR)
Diurnal decline
Lowest levels at night time called ‘Evening Nadir’
How do you observe and activate the pathways in lab?
Controlled/lab stressors (usually acute stress). We know that individuals respond to acutely stressful stimuli. We can attempt to mimic these situations in the lab
How do you observe and activate the pathways outside the lab?
Real world stress (usually chronic/enduring). Can observe and measure outside lab and compare higher and lower stress groups of individuals as they experience higher or lower stress periods
What are some examples of controlled/lab stressors?
Public speaking, mental arithmetic, mirror tracing, stroop task, multitasking, noise/white noise, injections, watching gore, cold pressor, dental treatment
What are some examples of real world stressors?
High stress jobs, excessive lifestyle, major life events, stressful living conditions, exam periods, caregiving
Do students have elevated cortisol?
People who reported higher perceived stress wake up with higher cortisol levels. When they go to bed they have higher levels of cortisol than those with low stress
Why do students have more health complaints?
People who are more stressed are showing extra activation of the hypothalamic Pituitary Adrena. Evidence by higher secretion of cortisol in morning and night. Makes people more vulnerable to illnesses
Why look at ecstasy use and cortisol?
Problems reported by ecstasy users are also related to elevated levels of cortisol - impaired memory, sleep problems, depression and anxiety, ill health.
Many ecstasy users have high elevated cortisol, more stressed by multitasking
What are some advantages of combining methods?
Able to assess effects of a life stressor on daily cortisol section and in response to acute stress. Heavy ecstasy users have elevated cortisol and greater response to acute stress. Maybe elevated cortisol levels are responsible for problems experienced by ecstasy users.
