U3 / AOS 1 | Nervous System & Stress

central nervous system

the brain and spinal cord

brain

regulates and guides all parts of the nervous system

more specifically:

* vital body functions
* receiving information from the outside world via senses and coordinating appropriate responses
* higher order functions (planning, thinking and learning)
* emotions, personality, sense of humour, etc…

brain function process

receives information from senses

the information travels to the brain

brain considers and processes info, linking it to thousands of other bits of info

then, the brain decides what happens next by responding appropriately

spinal cord

a cable-like column of nerve fibres that is encased by a series of bones called vertebrae

contains all three neurons (sensory, motor and inter)

spinal cord function

sends sensory/afferent messages towards the brain through afferent tracts, and then receives motor/efferent messages from the brain through the efferent tracts

function of central nervous system

receives sensory information from peripheral nervous system (body)

processes that sensory information

sends motor information back to the peripheral nervous system

peripheral nervous system

everything else outside of the central nervous system, which is comprised muscles, organs and glands (MOG) broken into the somatic and autonomic nervous systems

peripheral nervous system function

sends sensory information to the central nervous system

receives motor information from the central nervous system

somatic nervous system

a network of neurons within the body that transmit info from receptor sites to the central nervous system, and then carries information into the muscles to initiate voluntary movement

autonomic nervous system

a network of neurons that carry information between the central nervous system, organs and glands to ensure they are regulated without conscious awareness

broken into three more nervous systems

* sympathetic nervous system, parasympathetic nervous system and enteric nervous system

sympathetic nervous system

prepares the body for action, to deal with a potential threat and then activates the fight-flight-freeze response

parasympathetic nervous system

maintains the body is a state of homeostasis; returning the body to a state of calm following stress and/or heightened arousal

homeostasis

self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival

fight-flight-freeze response

initiated by the sympathetic nervous system and prepares the body to confront a stressful situation to optimise chance of survival

neurons

building blocks of the nervous system with over 200 types and are different depending on their function

e.g. pain or soft touch

sensory neuron

afferent, registers pain, carries sensations and feelings

interneurons

communicated between neurons, works heavily in brain coordinating processes

motor neurons

efferent, carries information to create voluntary movement

spinal reflex

an automatic, unconscious response that is initiated by neurons in the spinal cord, independent of the brain

spinal reflex causes and processes

caused by:

* pain, aid, survival

how does it occur?

* intercepted by interneurons in the spinal cord

why does it occur?

* faster reaction time for a larger chance of survival

soma

cell body

neural communication

neurotransmission using electrochemical energy allows…

excitatory

increasing the likelihood that the neuron will fire an action potential

inhibitory

decreasing the likelihood that the neuron will fire an action potential

types of neurotransmitters and neuromodulators

epinephrine | fight or flight

norepinephrine | concentration

dopamine | pleasure

serotonin | mood

GABA | calming

acetylcholine | learning

glutamate | memory

glutamate

a type of excitatory neurotransmitter that sends signals to the other cells to create large brain networks

helps with formation and retrieval of memory; enabling learning as a result

GABA

a type of inhibitory neurotransmitter that blocks or inhibits brain signals

largely associated with calming feelings of anxiety, stress or fear

neuromodulators

where neurotransmitters have specific effects on a particular neuron, _________ work together with neurotransmitters to enhance the inhibitory and excitatory effects, and create more widespread impact

neuromodulators role

involved in enhancing signal transmission

effective on a group of neurons and their impacts can last longer

they are still chemicals, and are released in the same way as neurotransmitters

dopamine

a neuromodulator that is involved in drive, motivation and motor movement has been associated with addictive behaviours such as gambling

low levels can cause motor movement issues and diseases such as Parkinson’s

serotonin

a neuromodulator which is our mood stabiliser; playing and important role in wellbeing, happiness, digestion, metabolism and stress

irregular levels have been linked to mental health problems (depression and anxiety)

parkinson’s disease

associated with low levels of dopamine (hence problems with movement), and with high levels of GABA (which influences dopamine and blocks more messages)

neuroplasticity

the brain’s ability to change itself as a result of experience there is two types

* adaptive


* developmental

adaptive plasticity

response to an accident

e.g. brain damage

developmental plasticity

natural change in the brain over time

e.g. newborns, pregnancy

synaptic plasticity

the process of neuroplasticity at a single cell level

* neurons that fire together, wire together

long-term potentiation

the increase in synaptic strength through high frequency stimulation of the neural pathway

long-term depression

the reduction of the efficiency of synaptic connections due to inregular activation of synaptic connections

neural processes

proliferation

migration

formation (sprouting)

pruning

myelination

proliferation

happens when we are born, we create a lot of neurons

migration

the neurons move to areas where they are needed the most

myelination

if the connection is consistently used, the connection will be strengthened

synaptic plasticity

possible as a result of three specific neural processes

* sprouting
* rerouting
* pruning

sprouting

involves creation of new connections between neurons

rerouting

involves re-establishing neural connections by creating alternate pathways

pruning

involves removing old neural connections that are not adequately activated

memory trace

enables learning to occur which is supported by glutamate

synaptic gap / synaptic cleft

a minuscule space between the terminal buttons of the presynaptic neuron and the dendrites of the postsynaptic neuron

lock and key process

neurotransmitters only affect postsynaptic receptor sites that have the correct shape for that particular molecule

agonist

substances that bind to synaptic receptors and increase the effect of the neurotransmitter

antagonist

a chemical or drug that binds to receptors in the brain and prevents an agonist from having a reaction

noradrenaline (norepinephrine)

a neurotransmitter that increases alertness, arousal, attention and is able to constrict blood vessels; maintaining blood pressure during stress affects your sleep-wake cycle, mood and memory

acetylcholine

plays a role in arousal, memory, learning and neuroplasticity. helps engage sensory functions upon waking helps people sustain focus part of the brain’s reward system helps maintain REM sleep

neural synapse

the site where communication occurs between adjacent neurons

stress

a state of psychological and physiological state of tension in response to a stimulus

distress

a form of stress characterised by a negative psychological state

eustress

a form of stress characterised by a positive psychological state

acute stress

a form of stress characterised by intense psychological and physiological symptoms that are brief in duration

chronic stress

a form of stress that endures for several months or longer

yorkes-dodson law

a law which proves that there is a a relationship between level of arousal and performance

stressor

a stimulus (internal or external) that prompts the stress response

internal stressor

a stimulus from within a person’s body that prompts the stress response

* unrealistic thoughts, fears, phobias

external stressor

a stimulus from outside of a person’s body that prompts the stress response

* homework, SACs, work

fight-flight-freeze stress response

occurs due to the arousal of the sympathetic nervous system due to an encounter with a stressor more prominent during acute stress

can include any adaptive responses that gives the body all necessary resources to maximise survival

cortisol

known as our ‘stress hormone’ primary role is to increase glucose to help different bodily functions repair damage done through stress, and to help combat stress itself after experiencing a FFF response

* the hormone is released to help sustain high levels of energy


* common in chronic stress


* hormone levels 9 times higher when stressed

prolonged stress

when suffering from stress over a prolonged period, the physiological impacts can have a negative impact on your health and wellbeing

* more susceptible to health concerns
* physiological symptoms due to psychological factors = **psychosomatic illness**

hpa axis

when our FFF response is initiated, adrenalin is released

if stress continues, the adrenalin release also must continue

the amygdala in the brain picks up the signal that there is a threat, which triggers the ___ to take control

general adaptation syndrome

the process your body goes through when you are exposed to any kind of stress, positive or negative

the 4 stages:

* alarm reaction (shock)
* alarm reaction (counter shock)
* resistance
* exhaustion

alarm reaction (shock)

resistance to stress = below normal

the body acts as if it is injured

blood pressure and body temperature drop

alarm reaction (counter shock)

resistance to stress = above normal

sympathetic nervous system activates

FFF response activates

adrenalin is released

resistance

resistance to stress = above normal

cortisol is released and all unnecessary functions shut down

individual appears normal

exhaustion

resistance to stress = below normal

resources are depleted

immune system is weakened and prolonged release of adrenalin has negative effects on body

e.g. stomach ulcers, individual is susceptible to illness and disease

strengths of gas

evidence of relationship between stress and illnesshighlights a predictable pattern that can be measured in individuals

limitations of gas

research was not conducted on humans (rats)doesn’t account for individual differences and psychological factors

lazarus and folkman’s transactional model of stress and coping

states that stress involves an encounter (transaction) between an individual and their external environment a stress response depends upon the individuals interpretation (appraisal) of the stressor, and their ability to cope with it

transactional model

demands \> resources \= stress

primary appraisal

an individual’s assessment of the situation

is it positive, benign or stressful?

if it is stressful, what type of stress?

**harm/loss** = has happened

**threat** = could happen

**challenge**

secondary appraisal

an individual’s assessment of the available resources to deal with demands

**internal resources** = character, personality

**external resources** = support networks, money, time

reappraisal

an important step in this model, as the consideration of one’s resources can change their perception of a situation

strengths of lazarus and folkman’s transactional model of stress and coping

accounts for individual differences in responses to similar situations

responds to changes in an individual’s response through the reappraisal stage, and explains why differences can occur within an individual’s response to situations as well

limitations of lazarus and folkman’s transactional model of stress and coping

lack of empirical evidence due to the subjective nature of data collected

there is often overlap between primary and secondary appraisal stages, and they are less discrete and reoccur more simultaneously than the model suggests

enteric nervous system

the gut, or gastrointestinal tract, is involved in processing food, absorbing nutrients, and exerting waste within the gut, there are living organisms called microbiota that maintain gut health and functioning

foods such as yogurt, kimchi and miso are high probiotic foods that contain live microbiota

microbiota

gut creates its own microbiome due to all of the \___ living inside

enteric ns correlation to stress

mayer et al (2015) conducted a study on animals that had microorganisms from their gut removed in order to better understand the relationship between stress and gut health

these animals were found to secrete more stress hormones and showed anxiety-like behaviours

recent research shows that humans with unhealthy gut microbiota is linked to higher stress levels, anxiety disorders, cognitive decline and autism

gut brain axis

the bi-directional relationship between the gut and the brain through the enteric and central nervous systems

e.g. if someone has bowel inflammation, it can impact their brain function, and likewise, if someone has depression, it can impact gut health

vagus nerve

the most important nerve in our parasympathetic nervous system, playing a role in our mood, digestion, immune response and heart rate

coping

the process of dealing with stress

coping strategies

physical exercise = ✓, using adrenalin from stress; slows down cortisol

meditation / relaxation = ✓, reduces physiological responses

social support = ✓, demands less likely to outweigh resources = less stress

alcohol / drugs = ✖, dopamine hit = pleasure which can also create addiction

approach strategies

behaviours that attempt to decrease the stress by addressing or finding solutions to the problem

e.g. applying for jobs, starting homework

usually a healthy response

avoidance strategies

failing to engage or deal with the stress by protecting oneself from psychological distress

e.g. ignoring or denying the situation

typically maladaptive and unhealthy responses and ultimately resort in even more stress

self efficacy

the belief in our own ability and that our actions can influence outcomes

resilience

our ability to bounce back following adversity

context-specific effectiveness

when the coping strategy used is appropriate for the unique demands of the stressor

must be a good resolution for the situation, consider situational factors, personal characteristics and demands of the stressor

the coping strategy which is most likely to be effective will also take account of the personal characteristics of the individual involved

coping flexibility

the ability of an individual to replace an ineffective coping strategy with a different strategy that is more suited or effective in dealing with the stressor

↪ it includes the abilities to:

     – recognise whether the use of a flexible coping strategy

is appropriate for a specific situation

     – select a coping strategy that suits the situational

circumstances

     – recognise when the coping strategy being used is

ineffective

     – discontinue an ineffective coping strategy

     – produce and implement an alternative coping strategy

when required.

allostatic load

the cumulative burden of chronic stress and life event, when environmental challenges exceed the individual ability to cope, then allostatic overload ensues

coping

a dynamic process involving constantly changing thoughts and behaviours so we can manage the demands (internal or external) of stressors we appraise as taxing or exceeding our resources

coping skills

learnt behaviours or techniques that help us solve problems or meet the demands of a stressor

coping strategy

the behavioural and psychological responses a person makes to a stressor that are intended to manage the stressor and reduce the physical and psychological stress related to it

coping effectiveness

the degree to which a coping strategy or combination of strategies is successful in alleviating stress

emotion focused strategies

an approach strategy aimed at managing the emotional distress caused by a stressor by changing the unpleasant emotions associated with it

e.g. embarrassment, fear, anxiety, depression, excitement and frustration.

these strategies allow us to feel better but **do not** solve the source of our distress meaning it is overall less effective than problem focused strategies