1. The Physiological Stress Response System – the relationship between mind & body
The IB Syllabus Says:
We will study: (The effect of psychological stressors (life events, daily hassles & workplace/occupational environment on physiological health) (we will also look at gender & cultural differences and stress management here)
We will study: (The interaction between personality/ cognitive style (Type A & Hardy
personality & stress related illness)

2. Background: The Nervous System
Consists of billions of nerve cells (neurons) which receive and pass on information within the nervous system
Miniscule cells (10 bn in the brain alone!)
Spaced out with little gaps called synapses in between them
Fire out chemicals to send information across the gaps.
Neurotransmitters = the chemical substances that allow communication between nerve cells.

3. The Nervous System
The CNS (Central Nervous System) includes the brain and the spinal cord and contains 90% of the bodies neurons
The PNS (Peripheral Nervous System) connects the CNS to the rest of the body – its divided into the Somatic Nervous system (which transmits information about body movements and external environment) and Autonomic Nervous System (which transmits information to and from the internal organs and glands)
The endocrine system also works alongside these

5. Stress A common topic – ‘I’m feeling stressed at the moment’
Stress – may be a reason for high prevalence of anxiety and depression, can also make us more vulnerable to colds and flu
Stress – not always negative – from an evolutionary perspective we need stress to survive but stress can become damaging

6. Key Terms - What is Stress?
Two ways to define stress:
1)A state of psychological tension and physiological arousal produced by a stressor (response to a stressor)
2) The lack of fit between the perceived demands of a situation and the person’s ability to cope (This is the transactional model -most popular model today – and we will be studying it in more detail) (if one feels they cannot cope – this leads to stress)

7. Key Terms - Stressor
Something in the environment (such as exams of work pressure, significant life events) that produces a stress response in a person (Selye, 1956)

8. How does it feel? How did you feel just before your exams last year?
Where did you feel it?
How were your emotions?

9. Background: How Does the Body Know it Has to Respond?
The body has 2 messenger systems:
1. Nervous System - travels through neurons (or nerve cells)
2. Endocrine System – hormones that travel through the blood

10. The body’s response to stressors
Two main responses – both involve the adrenal glands
Two adrenal glands – just above the kidneys each one made up from:
Adrenal cortex & Adrenal medulla: these release different types of hormones into the blood stream, and are controlled by two different pathways which are the hypothalamic-pituitary adrenal cortex (HPAC) pathway and hypothalamic-ANS-Adrenal medulla pathway (H-ANS-AM)

11. Location of important areas in the bodily response to stress
Relay center
between
CNS and
endocrine
System
Master gland
for releasing
hormones
Controls
The bodies
organs
The two
parts of the
adrenal gland

12. The hypothalamic-pituitary adrenal cortex pathway (HPAC)
Controlled by the hypothalamus and pituitary gland.
Hypothalamus is a small structure at the base of the brain
Pituitary gland ‘master gland’ as it releases many hormones into the bloodstream
The HPAC pathway is activated when higher brain centres evaluate a situation as stressful and instruct the hypothalamus to release the CRH hormone to stimulate the release of ACTH from the pituitary gland
The ACTH travels to the adrenal cortex and triggers the release of cortisol – a vital part of the stress response – mobilising energy reserves – heart rate & blood flow

13. The red arrows show the hypothalamic-pituitary adrenal cortex (HPAC) pathway
Stressor
Higher Brain Centres
(cortex & limbic systems)
Hypothalamus
CRH Hormone
Metabolic
effects on the body
(higher heart rate & blood
pressure to
get oxygen to muscles)
Brainstem
Pituitary gland
ACTH hormone in
bloodstream
Neural control
via autonomic
nervous system
cortisol
In bloodstream
Adrenal cortex
Adrenal medulla
adrenaline and
nor-adrenaline
In bloodstream

14. The hypothalamic- autonomic nervous system adrenal medulla pathway (H-ANS-AM)
The autonomic nervous system (ANS) is a network of nerve pathways running from the lower part of the brain (the brainstem) to the body’s organs.
Circulatory (blood) system
Various glands- including the
Adrenal medulla
Heart
Digestive system
The ANS is controlled by the higher brain structures, especially the hypothalamus

15. The autonomic nervous
system is
a part of the peripheral
nervous system
that  functions to
regulate the basic
visceral (organ)
processes needed
for the  maintenance
of normal bodily
functions.

16. this is done by the ANS without our conscious control
The role of the ANS is to maintain normal functioning of the body systems
e.g. when you run – the muscles need oxygen and energy, so carbohydrates and fats are converted into sugars and fatty acids in the bloodstream, and our heart rate and blood pressure increases
this is done by the ANS without our conscious control
To carry out these tasks there are two divisions to the ANS
The sympathetic subdivision
When activated: the body is
Aroused – heart rate and
blood pressure increase,
fats and carbohydrates are
mobilised, digestion slows
down ‘Sympathetic arousal’
Gets us ‘pumped up’
Stimulates the fight or flight
response
The parasympathetic subdivision
Heart rate and blood pressure return
to normal (decrease), d
igestion speeds up – calm
and bodily relaxation.
Phew – danger over, calms us down
again

17. The divisions of the Autonomic Nervous System
‘pumps up’
‘calms down’

18. Adrenaline– well known arousal hormone
The adrenal medulla is controlled by the ANS – and activation of the sympathetic branch triggers the release of hormones:
Adrenaline– well known arousal hormone
Nor-adrenaline– has similar effects
they increase heart rate and blood pressure – preparation for ‘fight or flight’
In stressful Situations the hypothalamus
activates
BOTH the HPAC and hypothalamic-ANS-Adrenal
medulla pathways

19. The green arrows show the hypothalamic-ANS-Adrenal medulla pathway (H-ANS-AM)
Stressor
Higher Brain Centres
(cortex & limbic systems)
Activates
The ANS sympathetic
subdivision
Via the brainstem
Hypothalamus
CRH Hormone
Brainstem
Pituitary gland
Metabolic
effects on the body
ACTH in
bloodstream
Neural control
via autonomic
nervous system
Cortisol
In bloodstream
Adrenal cortex
Adrenal medulla
Adrenaline and
Noradrenaline in
Bloodstream (increases heart
Rate & blood pressure)

20. The thin arrows show the
hypothalamic-ANS-Adrenal
medulla pathway (H-ANS-AM)
(colour in green)
The thick arrows show the
hypothalamic-pituitary
adrenal cortex (HPAC)
Pathway (colour in red)
Stressor
Higher Brain Centres
(cortex & limbic systems)
Activates
The ANS sympathetic
subdivision
Via the brainstem
Hypothalamus
CRH Hormone
Metabolic
effects on the body
(higher heart rate & blood
pressure to
get oxygen to muscles)
Brainstem
Pituitary gland
ACTH in
bloodstream
Neural control
via autonomic
nervous system
cortisol
In bloodstream
Adrenal cortex
Adrenal medulla
Adrenaline and
Noradrenaline in
Bloodstream (increases heart
Rate & blood pressure)
Activity: make your own diagram

21. Quick quiz…….
Give a step by step account of how the HPAC stress response pathway is activated
Give a step by step account of how the H-ANS-AM stress response pathway is activated

22. Question 1 mark scheme Gave full definition of abbreviation 1 mark
Mentioned higher brain center evaluating stressor 1 mark
Mentions hypothalamus and CRH hormone triggering pituitary gland 1 mark
Mentions ACTH hormone triggering Adrenal cortex to release cortisol in bloodstream
1 mark
5. Mentions effects of cortisol on body – increase in heart rate and blood pressure 1 mark
Total= 5 marks

23. Question 2 mark scheme Gave full definition of abbreviation 1 mark
Mentioned higher brain center evaluating stressor 1 mark
Mentions hypothalamus and Sympathetic subdivision of ANS and neural control via brainstem 1 mark
Mentions triggering of adrenal medulla to release adrenaline and nor adrenaline into bloodstream1 mark
Mentions effects of adrenaline/nor adrenaline on body – increase in heart rate and blood pressure 1 mark
Total= 5 marks

24. Models of stress
Selye (1956)– administered ‘noxious’ agents to rats and he found that they had same physiological response
Selye (1956) Called this ‘General Adaptation Syndrome’ (GAS)

25. Activating the body’s stress response
Selye (1956) identified the HPAC & hypothalamic-ANS-adrenal medulla (H-ANS-AM) pathways as the main components of the body’s response to stressors
He then thought about why they become activated
Both systems prepare the body for energy expenditure
Cannon (1914) called this the -
‘FIGHT OR FLIGHT RESPONSE’

26. ‘Fight or flight’
We have evolved from early humans – 10,000 years ago – and are behaviour is still adapted to that environment.
E.g. you see a Sabre toothed tiger – if not hunting – run for your life, if hunting attack
Same response – higher brain centres in the cortex and limbic system perceiving and evaluating the situation
Leads to the HPAC and hypothalamic-ANS-adrenal medulla pathway (H-ANS-AM) activation
Then when the emergency is over systems return to normal functioning

27. Fight or Flight Response
Increase
oxygen intake
Release stored
glucose
Divert resources
away from
digestion
Ready to expend energy,
either by fighting or by running away

28. Fight or Flight
Fido enters the classroom looking for trouble, you have 2 choices – run or take him on… For either of these options what would you need?
Energy!!!!
The Fight or Flight Response = the reaction of the nervous system in response to a stressful situation that produces energy to prepare the body extended and demanding amounts of effort

29. The Fight or Flight Response
An early evolutionary adaptation that is useful in dealing with physical threats
Helps us deal with short-term problems that can be solved by fighting or running
Unfortunately, many of the threats we face in our society do not fall into these categories…
in the modern world, most of the threats in today’s word a psychological, but dealing with these can trigger off the same response in the body as an attacking predator - so we become prepared for physical action with nowhere to go – this can have damaging effects in the long term

30. The General Adaptation Syndrome (GAS) (Selye, 1956)
The GAS has three phases
1st phase – The alarm phase, the presence of a stressful event is registered – could be a threat from an outside or physical stressor – such as an injury or illness affecting the body - the hypothalamic-pituitary adrenal cortex (HPAC) pathway and hypothalamic-ANS-Adrenal medulla pathway (H-ANS-AM) prepare the body for energy expenditure (fight or flight) – nowadays many of the stressors are psychological

31. The General Adaptation Syndrome (GAS) (Selye, 1956)
2nd phase is resistance – the body’s stress response is fully activated and coping with the stressor, so from the outside things appear to be back under control
The 3rd phase of exhaustion if the stressor is long lasting and chronic. Hormone levels are depleted, and stress related conditions such as raised blood pressure, ulcers, depression and anxiety may develop as stress systems become exhausted

32. Stress response systems activated
The three phases of the General Adaptation Syndrome (GAS) (Selye, 1956)
Phase 1: Alarm
Stress response systems activated
(HPAC & Hypothalamic ANS pathways)
Phase 2: Resistance
Body copes with stress
Phase 3: Exhaustion
Stress related illness may develop
Evaluation points?

33. Evaluation of GAS
Experimental support – first systematic attempt to explain the body’s response to stress based on experimental data – also the first to emphasise the role of the hypothalamic-pituitary adrenal cortex (HPAC) pathway and hypothalamic-ANS-Adrenal medulla pathways
Use of non human animals – Research carried out on rats, using physical stressors. Differences between the physiology of rats and humans, so its difficult to generalise his work to humans, however, his later work was done with humans
Individual differences- GAS ignores individual differences, e.g. Type A behaviour (Highly driven people who thrive in stressful situations). It assumes that we all respond the same way to stress, but personality and gender can also play role

34. Questions on stress:
What's the difference between the central and the peripheral nervous system?
Give a definition of stress
What is a stressor?
How does it feel to be stressed?
What are the two main messenger systems of the body?
What is the name of the model which explains stress stress that Selye (1956) introduced?
What are the names of the main pathways involved in the stress response?
When is the HPAC pathway activated?
Explain how the HPAC stress response pathway works.
What are the two divisions of the ANS?
What are the different roles of these two divisions?
Explain how the H-ANS-AM pathways works.
Complete your own physiology of stress diagram, clearly showing the HPAC and hypothalamic-ANS-Adrenal medulla (H-ANS-AM) pathways and explain them to each other (use colours/etc)
What is the name of the researcher who developed this model for stress?
When faced with a stressor, the body prepares for energy expenditure, Cannon (1941) called this the or response
Why is the fight or flight response activated?
What does the fight or flight response do to your body?
What are the three phases of the general adaptation syndrome response to stress?
Explain each of the GAS stages in detail
Make 2 evaluative points that relate to the GAS model of stress?