Unit 3 AOS 1 Flashcards
Nervous System and Stress
what is the human nervous system?
A complex, highly organised communication system between the body’s internal cells and organs and the external world.
Three main functions of the human nervous system?
- Receive information
- Process information
- Coordinate/Respond to information
what is the CNS comprised of?
brain and spinal cord
what is the CNS main function?
to receive and transmits neural messages to and from the PNS, process it and to activate appropriate responses
what is the brain and what is its function?
A highly complex organ contained within the skull that coordinates mental processes and behaviour, and regulates bodily activity. The brain is responsible for everything we think, feel and do.
what is the spinal cord?
long, thin bundle of nerves that extends from the base of the brain to the lower back.
what is spinal cords function?
to enable neural communication between the brain and the rest of the body, also initiates spinal reflexes
what tracts is the spinal cord comprised off?
Afferent tracts, which transmit sensory (afferent) messages from the PNS to the brain [incoming message to brain]
Efferent tracts, which transmit motor (efferent) messages from the brain to the PNS [outgoing message from brain]
what is the memory tip for sensory and afferent tracts/neurons?
SAME
what is the PNS comprised of?
All network of neurons within the body, outside of the brain and spinal cord (CNS).
Comprised of muscles, organs and glands (MOG)
what is the PNS further divided into?
the somatic and autonomic nervous systems
two main roles of the PNS?
- Carries information TO the CNS from the body’s muscles, organs and glands (internal) and from the sensory organs (external). [Sensory function]
- Carries motor information FROM the CNS to the body’s muscles, organs and glands. [Motor function]
what is the autonomic nervous systems (unconscious) function?
- Controls involuntary movement and functioning
- autonomous self regulates activity of visceral muscles, organs and glands without conscious control (involuntarily)
- Network of neurons that carry neural messages between the CNS and visceral muscles , internal organs and glands
- Responsible for keeping our internal functioning at a stable level (called homeostasis) and preparing our bodies to deal with threatening situations (fight flight response).
- Regulates activity of visceral muscles, organs and glands (e.g heart, lungs, sweat glands etc)
- Relays info to internal organs
- Connects CNS to internal organs and glands, self regulating
what are the two sub divisions of the autonomic nervous system?
Sympathetic NS and Parasympathetic NS
what is the sympathetic nervous system and functions?
- prepares body for action
- Activates internal muscles, organs and glands to prepare the body for vigorous activity or to confront or flee a stressful/ threatening situation.
- activates the fight/flight/freeze response
- activated by a stressor or fear stimulus and enhances survival by providing an immediate response, in a split second, to any kind of emergency
- increases arousal
what is the parasympathetic nervous system and functions?
- calms body for action
- In times of minimal stress and in the absence of threat, it helps to maintain the internal body environment in a steady, balanced state of normal functioning (homeostasis).
- Counterbalances the activities of the sympathetic nervous system
- Restores the body to a state of calm/equilibrium (homeostasis) after threat/cause of stress is no longer present
- counterbalancing and homeostasis are the 2 main functions
Why can’t we just stay in the sympathetic nervous system all the time?
Your body’s resources would become depleted and the MOG would not be able to maintain that level of arousal
Which is more dominant day-to-day?
Sympathetic NS OR Parasympathetic NS?
Parasympathetic nervous system, it is involved in everyday activities and routines
however they are both active at the same time, however one system is usually dominant at any given time
when does the autonomic nervous system function?
continuously, whether we are awake, asleep, active, under anesthetic or even in a coma, therefore maintains our survival
what is the somatic nervous systems function?
- Controls voluntary movement
- Initiates skeletal muscle movement
- Specialises in control of voluntary movements and communication of information to and from the sense organs
- Conscious awareness or voluntary control
- relays info to and from skeletal muscles
- Carries messages from sensory receptors in the body to the CNS, and motor messages from the CNS to skeletal muscles
what is the somatic nervous system comprised of?
network of nerves within the body, connected to our sensory receptors and skeletal muscles
what is the somatic nervous systems function in reference to SAME?
- Carries sensory (afferent) information from sensory receptor sites (skin, muscles, joints and tendons) and carried along sensory neural pathways to the CNS.
- Carries motor (efferent) information from the CNS along motor neural pathways to skeletal muscles to control voluntary movements.
physiological sympathetic response for pupils?
dilates to let light in to improve vision
physiological sympathetic response for salivary glands?
decrease salivation as not necessary, result of increased hormone secretion
physiological sympathetic response for heart?
accelerates heart rate to pump blood faster, increases blood flow, to enable high levels of physical activity
physiological sympathetic response for bronchioles of lungs?
dilates/relaxes to take in more oxygen, to increase oxygenation, enabling high levels of physical activity
physiological sympathetic response for stomach?
decrease contractions/inhibits digestion to conserve energy for high levels of physical activity
physiological sympathetic response for liver?
increase in glucose release to energise the body
physiological sympathetic response for gallbladder?
inhibits the release of bile, conserving energy by not contributing to digestion
physiological sympathetic response for adrenal glands?
stimulates hormone secretion (stress hormones) to energise body (increase in heart rate and blood pressure and breathing rate, relaxation of intestinal muscle)
physiological sympathetic response for bladder?
relaxes and slows contraction rate, causes excretion, to conserve energy
physiological sympathetic response for intestine?
inhibits secretion to conserve energy
physiological sympathetic response for blood pressure?
increases for higher levels of oxygen for activity
physiological sympathetic response for sweat glands?
increases perspiration to cool body
physiological sympathetic response for sex organs?
stimulated due to increase hormones
physiological parasympathetic response for pupils?
contracts according to external light levels, gives near vision, allows for appropriate amount of light for adequate vision
physiological parasympathetic response for salivary glands?
increases salivation back to normal functioning from normal hormone increased secretion levels
physiological parasympathetic response for heart?
slows heart rate back to normal, steady and regular, supports optimal and balanced functioning
physiological parasympathetic response for bronchioles of lungs?
contracts, to enable a steady and regular breathing rate for optimal functioning
physiological parasympathetic response for stomach?
increases contractions/stimulates digestion, allows for normal functioning/digestion
physiological parasympathetic response for liver?
decreases the release of glucose back to normal, allows body to rest and prevents depletion of energy stores
physiological parasympathetic response for gallbladder?
stimulates release of bile, allows for normal digestion
physiological parasympathetic response for adrenal glands?
inhibits hormone secretion, allows body to rest
physiological parasympathetic response for bladder?
increases to contractions return to normal functioning, urination can be controlled
physiological parasympathetic response for intestine?
increases contractions, enables normal functioning and optimal functioning
physiological parasympathetic response for blood pressure?
decreased/slows pumping of blood, returns to normal functioning, enables a steady and regular blood pressure for optimal functioning
physiological parasympathetic response for sweat glands?
decreases respiration, regulates normal and optimal functioning
physiological parasympathetic response for sex organs?
unstimulated caused by inhibited hormone secretion
what is a neuron?
nerve cell that receives and transmits neural information
what is the nervous system composed of?
The nervous system is composed of billions of neurons arranged in neural pathways along which neural messages are transmitted.
what are the three types of neurons?
- motor neurons (efferent neurons)
- sensory neurons (afferent neurons)
- interneurons
what are motor neurons?
Motor neurons (also known as efferent neurons), which transmit neural messages about motor movement from the CNS to the PNS
what are sensory neurons?
Sensory neurons (also known as afferent neurons), which transmit neural messages about bodily sensations from the PNS to the CNS
what are interneurons?
Interneurons, which transfer neural messages between sensory neurons and motor neurons. The CNS, including the brain and spinal cord, is made up of interneurons
what is a conscious response?
A conscious response to a sensory stimulus is a reaction that involves awareness to external and internal stimuli.
Involve purposeful, voluntary and intentional reactions
examples of conscious responses?
walking, talking, waving, putting on a jumper, waving (somatic NS functions)
what is an unconscious response?
An unconscious response to a sensory stimulus is a reaction that does not involve awareness.
It is involuntary, unintentional, automatic and we cannot ordinarily control its occurrence
Regulated by the ANS
examples of unconscious responses?
functioning of your heart, digesting your food (regulated by the ANS)
differences of conscious responses to unconscious responses?
- Reaction involves awareness
- Paid attention to stimulus
- Voluntary or intentional reaction
- Often goal directed or purposeful.
- Can be more complex response
- Tend to vary
- Can be learnt
- Can control it
differences of unconscious responses to conscious responses?
- Reaction does not involve awareness
- Don’t have to pay attention for it to happen
- Involuntary or unintentional
- Reflexive or automatic, increasing chances of survival
- Most are simple responses
- Tend to occur in the same way each time
don’t require learning - May not be able to control it
what is a spinal reflexes?
A spinal reflex is an unconscious and automatically occurring response to certain stimuli without any involvement of the brain (initiated by neurons in the spinal cord, called interneurons), it is a reflex involving contraction of skeletal muscles
A motor response has occurred before the brain processes a conscious perception of pain
what type of response is a spinal reflex?
The spinal reflex is an adaptive response, it saves time in a situation which may be very harmful to an organism (lessens damage/injury)
what are the steps of the spinal reflex?
- Receptor site (skin) receives sensory stimuli (prick)
- Sensory neurons transmit the message along afferent pathways to the spinal cord
- Interneurons in the spinal cord relay the message to motor neurons
- Motor neurons transmit the message along efferent pathways to hand muscles causing a withdrawal reflex
- Whilst the spinal reflex is occurs, sensory neurons also carry the neural message further up the spinal cord to the brain
- The brain then consciously perceives/interprets the sensory information as pain (WHY? = adaptive / for survival purposes so you can learn from it)
what is the cell body (soma)?
contains nucleus, contains DNA
what are the dendrites?
receives messages from other cells
what is the axon?
passes messages away from the soma to other neurons, muscles or glands
what are the myelin sheath?
covers the axon of some neurons and helps speed neural impulses
what is action potential?
electrical signal travelling down the axon
what are the terminal buttons?
stores and secrete neurotransmitters
how are neurons arranged?
in neural pathways in the nervous system, where neural messages are transmitted
what is the synapse?
Where two neurons meet (axon terminals of the pre-synaptic, the synaptic gap, and the receptor sites on dendrites of the post-synaptic neuron)
what are neurochemicals?
chemical substances that transmit neural information
where are neurochemicals released?
They are released from the presynaptic neuron, travel across the synaptic gap and are received by the receptor sites on dendrites of the post synaptic neuron.
what are the two types of neurochemicals?
Neurotransmitters and Neuromodulators
how do neurochemicals bind?
Each neurochemical has a distinct molecular structure that corresponds to a specific receptor site. Therefore, it will only bind to its matching/complementary receptor site.
what are neurotransmitters?
Chemical molecules that have an affect on one or two postsynaptic neurons
features of neurotransmitters?
→ Enables rapid communication between neurons
→ Neurotransmitters are fast-acting, localised - at a single synapse - and short lived
→ Meaning the neurotransmitter is released into the synapse, attaches to postsynaptic receptors and any excess neurotransmitter is reabsorbed or broken down by enzymes
(glutamate and GABA)
what type of neurotransmitter is glutamate?
The primary excitatory neurotransmitters that stimulate postsynaptic neurons to perform their functions (increases likelihood of post synaptic neuron firing an AP)
- Enhances information transmission by making post-synaptic neurons more likely to fire
what type of neurotransmitter is GABA?
The primary inhibitory neurotransmitters that block, prevent, or suppress postsynaptic neurons from firing an AP
what are the two most common neurotransmitters in the CNS?
glutamate and GABA, neurons in virtually every brain area use these two chemical messages to communicate with each other
- Glutamate is the second most abundant neurotransmitter in the brain
what are the roles of glutamate?
- The release of glutamate is associated with learning and memory
- The excitatory effects of glutamate form and strengthen synaptic connections between neurons that are repeatedly activated during learning
These connections represent memories of what has been learned
Thus, glutamate enables synaptic plasticity
what happens is there is too much or too little glutamate in the brain?
Too much or too little glutamate can be harmful to neurons and brain functioning as a whole.
Abnormally high concentrations of glutamate can result in overexcitation of receiving neurons causing neuronal damage and/or death.
what are the roles of GABA?
- Regulates postsynaptic activation in neural pathways, preventing over-excitation of neurons
- To fine-tune and maintain neurotransmission at an optimal or ‘best-possible’ level
- Without the inhibitory effect of GABA, activation of postsynaptic neurons might get out of control causing uncontrolled activation which may result in seizures
- able to inhibit heightened awareness therefore reduces anxiety and important role in preventing seizures
- It is involved with the regulation of anxiety and is associated with calmness
how to glutamate and GABA balance each other?
- The inhibitory effect of GABA counterbalances the excitatory activity of glutamate and vice versa
- Consequently, GABA and glutamate have important roles in regulating CNS arousal
- An excess or over-production of particular neurotransmitters is associated with particular disorders
what are neuromodulators?
Chemical molecules that have an effect on multiple postsynaptic neurons. (dopamine and seretonin)
features of neuromodulators?
- Neuromodulators have widespread modulatory effects as they can influence large areas of brain tissue.
- Neuromodulators produces relatively long-lasting effects, as they modulate neural activity more slowly than neurotransmitters.
- Neuromodulators diffuse (spread) through large areas of the brain; they are slow acting but will bring about long-lasting change to neurons and synapses affected.
- Like neurotransmitters, they bind to their specific receptor sites to have an effect on groups of post-synaptic neurons.
how can neuromodulators can also affect neurotransmitters?
→ changing the responsiveness of the receptor sites of a particular neurotransmitter, further enhancing excitatory or inhibitory effects
→ Changing the neurotransmitter release pattern of the presynaptic neuron
what is dopamine responsible for?
Dopamine is a neuromodulator primarily responsible for voluntary motor movement, the experience of pleasure, and reward based learning.
where is dopamine produced?
Dopamine is produced in the substantia nigra, as well as the ventral tegmental area, both located in the midbrain.
what effect does dopamine have on the post-synaptic neuron?
Dopamine can have excitatory and inhibitory effects on the post-synaptic neuron, depending on the type of receptor sites present at the particular brain location
what roles does dopamine have?
- Coordinates voluntary motor movement
- Important role in reward based learning
- Plays a role in motivation and addiction
- Role of dopamine in thirst and drinking
- Plays a role in hunger and eating
how does dopamine coordinate voluntary motor movement ?
→ Dopamine produced in the substantia nigra enables smooth, coordinated muscle movement
how does dopamine play an important role in reward based learning?
→ When someone is rewarded for doing a behaviour, dopamine that is produced in the ventral tegmental area is released, which is associated with the feeling of pleasure.
how does dopamine play a role in motivation and addiction?
→ Rewarding behaviors that trigger the release of dopamine have a pleasurable consequence for the person, and therefore more likely to be done again. In this way, dopamine can motivate the person to engage in rewarding behaviours over and over. Therefore, addictive behaviours, such as gambling and drug use, often provide intense pleasurable rewards for people, motivating them to repeat a behaviour, and therefore resulting in an addiction.
how does dopamine play a role in thirst and drinking?
→ The process of sipping water releases dopamine in the reward pathway, procucing feelings of pleasure
→ This suggests that the act of drinking water itself is rewarding , not the actual hydration.
how does dopamine play a role in hunger and eating?
→ consumption of food releases dopamine and provides a sense of pleasure.
→ this increases the likelihood of eating food the next time we experience hunger
→ hunger results from a decrease of dopamine levels in the brain, this triggers the sensation of hunger, then when we eat, dopamine levels increase, we experience pleasure and this pattern is reinforced
→ when we eat something we have been craving, the brain releases more dopamine into the reward pathway
where is seretonin produced?
Serotonin is produced from the raphe nuclei, which are masses of neurons in the brainstem
what effect does seretonin have on the post-synaptic neuron?
Serotonin has inhibitory effects on the
postsynaptic neurons
what roles does serotonin have?
- Mood regulation and stabilisation
- Regulates the sleep-wake cycle
what role does serotonin have in mood regulation and stabilisation?
→ Appropriate levels of serotonin in the brain enable a person to experience stable and positive moods, promoting wellbeing.
→ Low levels of serotonin are linked with mental illnesses such as depression, resulting in prolonged negative moods, reduced interest in daily activities and feelings of extreme worthlessness or excessive guilt.
→ medications to treat depression increase serotonin levels or target serotonin receptors in the brain (antidepressants are a type of SSRI (a selective serotonin reuptake inhibitor) meaning they block/prevent the reuptake of serotonin after it has been released, resulting in greater than usual levels of serotonin being available. This results in an instant & immediate improvement in mood.
what role does seretonin have in regulating the sleep-wake cycle?
→ which is the 24 hour cycle of sleeping and waking. Serotonin influences both quality and quantity of sleep as well as feelings of alertness and wakefulness during the day
what other roles does seretonin have?
Depending on the receptor sites it binds to and the brain area it acts upon, serotonin can also play a role in appetite, digestion and arousal.
what is synaptic plasticity?
The ability of synaptic connections to change over time in response to activity or experience/learning.
what does synaptic plasticity include?
This includes the formation, strengthening or weakening of synaptic connections.
The experiences you have throughout your life modify neural synapses, causing them to physically change.
what is learning?
Learning is the process of acquiring knowledge, skills, or behaviours through experience.
what is memory?
Memory is the process of encoding, storing, and retrieving information that has been previously encountered.
when do learning and memory occur?
Learning and memory are processes that constantly occur throughout life.
We learn and form new memories every day as we experience, engage, and interact with the environment.
how is synaptic plasticity related to learning and memory?
Synaptic plasticity is the fundamental mechanism of memory formation that leads to learning.
When we form new memories, neural synapses in the brain physically change by establishing new neural pathways that incorporate these memories and represent what has been learnt.
These neural pathways that form during learning are referred to as memory traces, with each memory trace representing a different memory.
what are the mechanisms of synaptic plasticity?
- sprouting
- re-routing
- pruning
what is sprouting and how is it helpful?
- the ability of dendrites or axons to develop new extensions or branches.
This increases the reach of the neuron and enables the formation of new synaptic connections.
what is re-routing and how is it helpful?
- the ability of a neuron that is connected to a damaged neuron to create an alternative synaptic connection with an undamaged neuron.
The neuron abandons its connection with the damaged neuron and forms a new connection.
Thus, the synaptic connection is reestablished via an alternative route, restoring brain functioning.
what is pruning and how is it helpful?
- the elimination of synaptic connections that are not adequately activated or ineffective/weak/unused
When neural synapses are not used, they are removed or ‘pruned’.
This is necessary to allow for stronger and more essential synaptic connections, consequently enhancing the efficiency of brain functioning
what are the two forms of synaptic plasticity that underlie learning & memory?
- LONG TERM POTENTIATION
- LONG TERM DEPRESSION
what is long-term potentiation (LTP)?
Refers to the long lasting strengthening of synaptic connections, due to repeated stimulation of neural pathways, resulting in the enhanced functioning of neural pathways.
*involves sprouting and re routing
what does long-term potentiation (LTP) cause?
- Strengthens the likelihood of the neurons in this pathway firing again in future.
- This causes permanent functional and structural changes that lead to a memory being stored.
what is long-term potentiation (LTP) is associated with?
- Increased release of neurotransmitters
- Increased receptor sensitivity
- Changes to the structure of the relevant synapses
what are the structural changes in the synapse in LTP?
- Growth of more receptor sites on the post synaptic neuron’s dendrites.
- Growth of dendritic spines on the post synaptic neuron’s dendrites
- Synaptogenesis occurs, which is the creation of new synapses.
what are the functional changes in the synapse in LTP?
- Initially there is an increased release of neurotransmitters by the pre-synaptic neuron.
- Due to increased sensitivity of receptor sites (post), eventually less NTs are required for the post synaptic neuron to fire.
- More efficient/faster communication overall.
what is long-term depression (LTD)?
LTD is the long-lasting decrease in the strength of synaptic transmission which results from prolonged and repeated low level stimulation or a lack of stimulation
* involves pruning and re routing
what does long-term depression (LTD) cause?
- It also results in the postsynaptic neuron becoming less responsive.
- Thus, weakening the synaptic connection and therefore the effectiveness of the communication.
what is the importance/purpose of long-term depression (LTD)?
- Allows us to prune or eliminate useless/unwanted/unimportant memories.
- Allows us to create new memories and clear unwanted memories
- Allows us to adjust, edit or correct our thinking when problem solving, or our movements if performing a skill.
- Also provides a basis for blocking or eliminating inappropriate or unwanted feelings or behaviours.
what are the features of long-term potentiation (LTP)?
- enhanced/more efficient synaptic transmission
- post-synaptic neuron becomes more easily activated
what is the process of long-term potentiation (LTP)?
- results from repeated stimulation/activity
what is the purpose of long-term potentiation (LTP)?
- decreases the likelihood of forgetting (facilitates learning ad memory)
what are the features of long-term depression (LTD)?
- less efficient synaptic transmission
- post-synaptic neuron becomes less responsive
what is the process of long-term depression (LTD)?
- results from lack of co-ordination or sub-optimal stimulation
what is the purpose of long-term depression (LTD)?
- increases likelihood of forgetting
- enables thinking to be adjusted or corrected
what does LTD plus LTP equal?
more efficient neural pathways as a result of neural plasticity
what is stress?
A state of psychological and physiological arousal produced by internal or external stressors that are perceived by the individual as challenging or exceeding their ability or resources to cope
what is a stressor?
any person, situation or event that produces stress
what can be a stressor?
*Virtually anything can be a stressor and therefore a cause of stress to an individual
whats an internal stressor and example?
originate within the individual (cognitive or biological)
→ Results of personal problems, physical pain, a health scare,attitude, nervous system dysfunction
whats an external stressor and example?
originate outside the individual from situations and events in the environment (social or environmental)
→ Too much homework, being nagged by parents, being threatened by someone, victim of a crime
whats a stress reaction?
The physiological and psychological result of stress
what does psychological relate to in stress ?
mental processes (thoughts, feelings, perceptions)- ie. how you interpret a stressor. In this aspect, stress is a subjective experience; our individual interpretation of a stressor varies
what does physiological relate to in stress?
refers to bodily (biological) processes (e.g. physical symptoms of stress)
what is eustress?
a positive psychological response to a perceived stressor, indicated by positive psychological states such as feeling enthusiastic and motivated, excited, active and alert
features and examples of eustress?
- “good stress”
- Typically short term, and provides motivation to achieve a goal or reach peak performance
E.g. First date, going on a rollercoaster, getting an A+, going to a big party
what is distress?
a negative psychological response to a perceived stressor, indicates by the presence of negative psychological states such as anger, anxiety, nervousness, irritability or tension
features and examples of distress?
- Can be short term, but can also persist for weeks or months if not managed
- Waiting in a line when rushed, watching a horror movie, financial pressures, relationship problems, failing an exam, friendship breakdowns
how does the body and mind respond to the stress?
the physiological response is the same (sympathetic NS is dominant - known as a non specific stress response) however the psychological aspect is different
what is a physiological stress response?
- Relate to how the body reacts to a stressor
features of a physiological stress response?
- Usually experienced in similar ways between different between people and in response to different stressors
- The length of time that the stressor demands attention and/or effort to cope varies
what are the two biological stress responses?
- The flight-fight-or-freeze response to acute stress
- The release of cortisol during chronic stress
what is acute stress?
a form of stress characterised by intense psychological and physiological symptoms that are brief in duration
what is flight-fight-or-freeze?
an involuntary and automatic response to a threat that takes the form of either escaping it, confronting it or freezing
what is flight?
Organism flees/runs away from the stressor
what is fight?
Organism confronts/fights the stressor
what is freeze?
Organism experiences temporary immobility and shock in response to the stressor (organism keeps still & silent)
what are the features of fight or flight?
- Both Involve the activation of the sympathetic nervous system
- Prompt the release of adrenaline, noradrenaline and cortisol into the bloodstream from adrenal glands which allows the body to quickly flee or confront the threat
what are the features of freeze?
- Time to orient/ assess the stressor or hide (less liely to be seen)
- Involves the parasympathetic nervous system being dominant
- Some functions drop below normal – blood pressure, & heart rate, reduced mobility, reduced vocalisation (ability to make speech or sounds) (conserves energy)
- Can involve simultaneous activation of sympathetic, as the freeze response often only last seconds
what is cortisol?
The primary stress hormone
what is chronic stress?
ongoing demands, pressures and worries that are long-lasting
Resulting in increased arousal level that persists over a relatively long time
where is cortisol produced?
Produced by the adrenal glands (located above your kidneys)
what is cortisol involved in?
Involved in many biological functions eg. Metabolism, blood pressure, insulin release, CNS activation and overall immune function
what is the main effect of cortisol?
Main effect of cortisol is to energise the body by increasing energy supplies such as glucose
what is measuring cortisol used for?
The level of cortisol circulating in the bloodstream is commonly used as a measure of stress by researchers
what are the short term (adaptive) effects of cortisol?
its effects on the body are positive as it increases our chances of survival by preparing the body for action.
examples of short term (adaptive) effects of cortisol?
Increasing blood sugar levels, Improving metabolism, Energising the body, Reducing inflammation
what are the long term (maladaptive) effects of cortisol? (long)
prolonged or intense stress, results in negative effects on the body and a suppressed immune system as cortisol levels in the body are too high.
This is when additional physiological responses are required as the body cannot maintain the intensity of the FF reactions.
This is when the HPA axis is activated, which involves the hypothalamus, the pituitary gland and the adrenal cortex to secrete cortisol which persist longer than the initial FF response
examples of long term (maladaptive) effects of cortisol?
impaired cognition, high blood pressure and lowered immunity, high anxiety, brain fog, cardiovascular disease, diabetes and mental illnesses
what does GAS stand for?
Selye’s General Adaptation Syndrome
what is GAS?
The general Adaptation syndrome (GAS) is a three-stage physiological response to stress that occurs regardless of the stressor that is encountered.
what are the stages of GAS?
Stage 1: Alarm reaction - shock and counter shock (immediate response)
Stage 2:resistance (maximise resources to cope and adapt)
Stage 3: exhaustion (vulnerable and weak)
what happens in the alarm reaction phase?
general defensive reaction to the stressor, and results in a state of tension and alertness, and a readiness to respond to the stressor
what happens in the alarm reaction - shock phase?
- Occurs when the person (or animal) first becomes aware of the stressor.
- the body goes into a temporary state of shock, and its ability to deal with the stressor falls below its normal level.
- Physiologically, the body reacts as if it were injured; for example, blood pressure and body temperature drop, and a temporary loss of muscle tone is experienced.
what happens in the alarm reaction - counter shock phase?
- Then the body rebounds from this level with a reaction that Selye called counter shock.
- During counter shock, the sympathetic nervous system is activated and the body’s resistance to the stressor increases.
- The organism’s response is a fight–flight response 🡪 It becomes highly aroused and alert as it prepares to deal with the stressor.
- Adrenaline and cortisol are released into the bloodstream and the organism’s heart and respiratory system respond by accelerating. This supplies the muscles with more energy (glucose and oxygen), allowing the organism to ‘fight or flee’, as needed.
what happens in the resistance phase?
- If the stressor is not dealt with immediately, and the state of stress continues, energy is still required in order for the body to cope with and adapt to the stressor
- Body’s resistance to the original stressor rises above normal – individual will generally appears as though all is normal
- Physiological arousal remains higher than normal (but lower than the alarm-reaction stage)
- Cortisol levels increase to energise the body and repair damage, however, this compromises our immune system. (There is prolonged release of cortisol).
- It also significantly lowers our ability to resist additional stressors.
- This is because the body directs its resources to fighting the current stressor, meaning it may not have any resources left to fight off additional stressors (eg. infection).
- All unnecessary physiological processes are shut down. For example, digestion, growth, sex drive and menstruation stall.
Note: If the original stressor has been dealt with successfully the body will return to homeostasis, however, if not dealt with the individual moves into the stage of exhaustion.
what happens in the exhaustion phase?
- During the exhaustion stage, some of the alarm reaction changes may reappear, but the body cannot sustain its resistance and the effects of the stressor can no longer be dealt with.
- Because the organism has been trying to deal with the stressor for a prolonged time its resources have been depleted, its resistance to disease is very weak, and it becomes more vulnerable to physical and mental disorders.
- Immune system is left weakened and prolonged release of adrenaline has negative effects on the body
what is the exhaustion stage characterised by?
- Extreme fatigue
- High levels of anxiety
- Symptoms of depression
- Nightmares
- Impaired sexual performance
- Physical disorders such as hypertension, gastrointestinal problems and heart disease
- Physical wear and tear, especially in organs consistently trying to deal with the stressor during resistance stage; attributable to the immune-suppression and prolonged levels of cortisol in the bloodstream
In extreme cases, if the stress continues further, the organism may even die
strengths of GAS model?
- Further developed understanding of the link between stress and disease
- Identified biological processes associated with the body’s stress response
- Further develops understanding of the body’s resources to cope and that prolonged stress can deplete resources
limitations of GAS model?
- One size fits all model (assumes everyone has the same predictable and automatic physiological response)
- Does not explain individual differences
- Does not account for psychological / cognitive (subjective) aspects of stress 🡪 e.g. individual interpretations of stressors
- Does not explain why people experience different physiological reactions to chronic stress – e.g. some CVD & some skin rashes
- Selye’s model was primarily based on research on animals (limits generalizability to humans) – demonstrates why biological processes are overemphasized
what are psychological factors which influence how we respond to stressors?
- Prior experience with stressors and stress responses
- Attitudes
- Motivation
- Level of Self-esteem
- General outlook on life (e.g. optimism vs. pessimism)
- Personality characteristics
- Coping skills
- Perception of how much control we have over a stressful event/situation
what is the Lazarus and Folkman’s Transactional Model of Stress and Coping?
This model of stress describes and explain individual differences in how people respond to a stressor from a psychological perspective.
what are the two key psychological factors that determine the extent to which an event (or situation) is experienced as stressful in the Lazarus and Folkman’s Transactional Model of Stress and Coping?
- the meaning of the event to the individual
- the individual’s judgment of their ability to cope with it.
what does the Lazarus and Folkman’s Transactional Model of Stress and Coping propose?
Proposes that stress involves an encounter (‘transaction’) between an individual and their external environment, and that a stress response depends upon the individual’s interpretation (‘appraisal’) of the stressor and their ability to cope with it.
Furthermore, an individual’s appraisal of the situation and their resources for dealing with that situation determine whether or not they experience stress and the nature of their stress response.
Imbalance between a person’s appraisal of the stressor and their ability to meet those demands = STRESS
what is apprasial?
- Appraisal is not necessarily a conscious process.
- However, it is always subjective and therefore a highly personal process.
- It also depends on our estimation of our ability to cope with the stressor.
- Therefore, two individuals may assess the same potential or actual stressor differently.
what two different types of appraisal of an event is in the transactional model of stress and coping?
These are called primary appraisal and secondary appraisal, and they occur in a two-step sequence in response to a potential stressor
what is primary appraisal?
In a primary appraisal, we evaluate or ‘judge’ the significance of the event
what are the outcomes of primary appraisal?
The outcome of a primary appraisal is the decision about whether the event is: IRRELEVANT, BENIGN-POSITIVE or STRESSFUL
what happens after primary appraisal?
If we decide the situation is STRESSFUL, then we engage in additional appraisals that involve deciding if a situation is harmful, threatening or challenging.
what is harm/loss primary appraisal?
an assessment of how much damage has already occurred
what is threat primary appraisal?
an assessment of harm/loss that may not have yet occurred but could occur in the future
what is challenge primary appraisal?
an assessment of the potential for personal gain or growth from the situation
what is secondary appraisal?
We evaluate our coping options and resources and our options for dealing with the event.
what are coping options and resources described as?
The coping options and resources available may be internal (e.g. strength and determination) or external (e.g. money and support from family or friends).
what are coping strategies are categorised into?
Problem-focused or Emotion-focused
what is a problem-focused coping stratergy?
constructive strategies involving behaviour modification to deal with the situation. E.g. taking control, information seeking, evaluating pros and cons etc.
what is a emotion-focused coping strategy?
strategies that do not deal with the stressor but attempt to reduce the negative emotions associated with the stress. E.g. venting, crying, eating, denial, distraction etc.
what happens with coping strategies that leads to stress?
inadequate coping strategies
what happens with coping strategies that don’t leads to stress?
Coping resources are adequate
= NO STRESS
Or Eustress (initial potential stressor now seen as a challenge
what are the strengths of the Lazarus and Folkman Model?
- Focuses on psychological determinants of the stress response over which we have control
- Emphasises the personal nature and individuality of the stress response
- Views stress as an interaction with the environment in which the individual has an active role
- Explains why individuals respond in different ways to the same sorts of stressors
- Allows for the fact that stressors and the circumstances under which they occur can change over time
- Allows us to change our thinking about a stressor and our response
what are the limitations of the Lazarus and Folkman Model?
- Difficult to test through experimental research because of the subjective nature of individual responses to stress
- Individuals may not always be conscious or aware of all the factors causing them stress.
- We can experience a stress response without ever having thought about or appraised a situation/event.
- The model overlooks physiological responses
- The linear approach of the model does not allow for individual variation in progression through it’s stages
- Primary and secondary appraisals can interact with one another and are often undertaken simultaneously
- Primary and secondary appraisals are difficult to isolate for study as separate variables.
what are the similarities between the GAS and Transactional Model of Stress?
- both are models of stress response
- both have different stages
what are the differences between the GAS and Transactional Model of Stress?
- GAS biological and transactional is psychological
- tested on different species (GAS - rats, T- humans)
- GAS - one size fits all, T - subjective
- GAS - same reaction to all stressors, T - dependant on servereness of stressors
what is a coping strategy?
A coping strategy is a specific method, behavioural or psychological, that people use to manage or reduce the stress produced by a stressor.
how will coping strategies work?
Some strategies will ‘work better’ and therefore be more effective than others, depending on a range of factors, such as the nature of the stressor (e.g. acute or chronic, hassle or catastrophe), the individual (e.g. their appraisals, coping flexibility, personality, access to support) and the stressful event itself.
what is context-specific effectiveness?
A coping strategy is considered to have context- specific effectiveness when there is a match or ‘good fit’ between the coping strategy that is used and the stressful situation.
what do effectiveness of coping strategies depend on?
- A specific coping strategy can be more or less effective in different situations.
- It must consider the stressor, the physical environment (circumstances or context of the situation) and the individual involved.
- Effectiveness of coping strategies also depend on personal characteristics of the individual involved (e.g. personality, knowledge, access to social support)
what is coping flexibility ?
Coping flexibility to refers to the ability to effectively modify or adjust one’s coping strategies according to the demands of different stressful situations.
what is the abilities of coping flexibility?
- evaluate a coping strategy
- modifying an existing strategy
- discontinue an ineffective coping strategy or
- implement an alternative coping strategy when required
what does the model describe coping flexibility as?
It is an adaptive personality trait as it allows us to meet the challenges of different situations.
The model describes coping as a process that is responsive to situational changes rather than one that remains relatively stable across situations.
what do people with high coping flexibility do?
- Readily adjust their strategies to suit a situation.
- Tend to use a variety of strategies in different situations.
- Context-specific effectiveness tends to be high (use different types of coping strategies which are a good fit with the specific situational demands)
- Tend to experience much lower stress levels.
what do people with low coping flexibility do?
- Use the same type of strategy across different situations
- Continue to persist with an ineffective strategy.
- Context-specific effectiveness tends to be lower.
- Tend to experience higher stress levels.
what can coping strategies be categorised into?
Individuals coping strategies can be categorised into approach and avoidance coping strategies; these terms refer to the focus of an individual’s activity either toward or away from the stressor.
what do approach and avoidance coping strategies aim to do?
Both strategies aim to reduce stress levels and help an individual cope, however the method to achieve this differs
what does approach strategy mean?
DEAL DIRECTLY/ CONFRONT STRESSOR
what does avoidance strategy mean?
DO NOT DIRECTLY DEAL WITH STRESSOR
what are approach coping strategy features?
- Involves efforts to confront stressor and deal directly with its effects
- Activity is focused towards the cause of stress
- Focus on a solution to the underlying problem
- Approach strategies involve engagement with the stressor
positives of approach coping strategy?
- Allows the individual to feel in control of the situation, i.e. proactive.
- Considered a more adaptive and effective approach.
negatives of approach coping strategy?
- Initially may increase stress levels whilst the individual is directly engaged with the stressor and its causes.
- May require a lot of the individual’s energy and focus to deal with the stressor, thereby neglecting other aspects of their lives.
what are avoidance coping strategy features?
- Involves efforts to avoid a stressor and deal indirectly with it and its effect
- Activity is focused away from the stressor
- No attempt to actively confront it
- Involve behavioural or emotional disengagement
positives of avoidance coping strategy?
- Not all avoidance strategies are maladaptive or ineffective
- sometimes it allows for an individual to deal with one stressor at a time
- allows for energy conservation when nothing can be done
negatives of avoidance coping strategy?
- Maladaptive approach as it does not help people to develop effective strategies to use in the future.
- People who use these strategies are more likely to suffer from stress-related conditions.
- increased vulnerability to mental health problems and stress-related physical problems, such as hypertension and cardiovascular disease
- research suggests that individuals who engage in long term use of avoidance strategies are associated with substance use and beahvioural problems
what is the gut-brain axis?
The GBA refers to the network of bi-directional (two-way) neural pathways that allows communication between gut microbiota (bacteria in the gastrointestinal tract) and the brain.
what are psychologists interested in the GBA?
Psychologists are interested in how the GBA influences our mental wellbeing, stress & behaviour
what does the GBA consist of?
The GBA includes the CNS, the sympathetic and parasympathetic branches of the autonomic nervous system, the enteric nervous system (ENS), the vagus nerve and the gut microbiota.
what is the enteric nervous system(ENS)?
is the network of nerves in the gut, and is a subdivision of the autonomic nervous system
what is the vagus nerve?
the longest nerve in the body running from the brainstem to the intestines that enables communication between the gut and the brain (bi-directional)
- the longest cranial nerve that connects the gut and the brain, enabling them to communicate
what is gut microbiota?
living microorganisms in your gut that help maintain gut health and functioning, known to produce and release several neurotransmitters such as GABA, serotonin and dopamine
what is gut microbiome?
all the genes of the microorganisms that live in the gut
what is the enteric nervous system branched from?
A branch of the autonomic NS which manages the functions of the digestive system
what is the enteric nervous system made up of?
- 9 metres long including the oesophagus, stomach, anus and both the small and large intestines.
- Made up of 100-500 million neurons
what are the functions of the ENS?
- Controlling motility: the stretching & contracting of muscles in the GI tract that enable food to move through
- Detecting nutrients for the body to use
- Immune and defence responses (against toxic foods and bacteria)
- Maintaining the chemistry of the gut (hormones, digestive acids & neurotransmitters)
- Communicating with the CNS
how does communication occur in the GBA?
Communication between the gut and brain occurs through the vagus nerve
what are the nerve fibres in the GBA vagus nerve?
- 90% of the vagus nerve fibres are afferent (sensory) connections that send signals from the gut to the brain (e.g. pain, fullness, hormones)
- 10% send efferent (motor) signals from the brain to the gut (e.g. release of saliva and stomach acids, information about incoming food)
how many gut microbiota is there and where?
A system of 100 trillion bacteria and other microorganisms that in the GI tract.
what is a healthy gut microbiota?
one that is diverse; meaning there is a good balance of ‘good’ and bad‘ bacteria
what does a healthy gut microbiota indicate?
This is a strong indicator of good physical and mental health.
what is microbiota influenced by?
Microbiota is influenced by genetics, diet, metabolism, age, illness, geography, changes in diet, antibiotic treatment and stress (diversity of microbiota decreases with age)
what is dysbiosis?
When microbiota become less diverse (ie. no healthy balance of bacteria) this is known as Dysbiosis.
what can dysbiosis cause?
Dysbiosis can cause a range of digestive illnesses, suppressed immune system and can impact cognitive processes, feelings of stress, depression and some social behaviours.
how is information about dysbiosis communicated to the brain?
This information is detected directly in the gut, converted into action potentials and transmitted to the vagus nerve which then transmits it to the brain.
what foods help us achieve good gut health?
Foods such as yoghurt, kimchi, pickled vegetables, Sauerkraut, Kombucha, miso are examples of high probiotic foods which contain live microbiota
Fermented food is rich in probiotics
Conversely, antibiotics and fatty/processed foods strain our gut health
what are the features of the emerging research with GBA?
- Studies on the GBA are still new
- Links have been found links between gut health and psychological processes and behaviour
- Difficult to draw definitive conclusions, so we discuss this research by referring to possible connections between our gut and overall health
what are germ-free animals?
Germ-free animals are animals that have had microorganisms from their gut microbiota removed (most studies use mice)
what has research looked at so far in germ-free studies?
Effects of antibiotics, probiotics and faecal transplants (transferring poo from healthy mice to germ free mice
what are germ-free studies?
Germ-free animal studies compare certain behaviours and psychological processes in germ-free animals with non-germ-free animals
are germ-free studies related to humans?
although these studies demonstrate a gut-brain relationship they are not directly generalisable to humans
what are antibiotics?
Antibiotics are used to treat or prevent some types of bacterial infection. They work by killing bacteria or preventing them from spreading
what are probiotics?
Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota.
what do probiotics help do?
Help your body maintain a healthy community of microorganisms or help your body’s community of microorganisms return to a healthy condition after being disturbed.
what was the impact on social behaviour in germ-free studies?
- Germ-free mice exhibit less social interactions
- They displayed more antisocial behaviours such as avoiding other mice
- Transferring faecal matter from mice with healthy microbes improved these behaviours
what was the impact on cognition in germ-free studies?
- Germ free mice who were given long term antibiotic treatment showed poorer memory function
- In humans: studies have shown that gut microbiota can influence likelihood of experiencing cognitive decline & Autism SD
- Probiotic treatments resulted in improvements in memory and cognition
what is the bi-directional relationship with stress and gut microbiota?
Bi-directional relationship - experiencing stress negatively impacts the diversity of gut microbiota and having an unhealthy gut microbiota is linked to higher stress levels and a hyperactive HPA
Explains why often when you feel stressed you may experience digestive discomfort
Thus, stress is clearly linked to dysbiosis in the gut
what is a prolonged activation of the HPA axis has been linked to?
Prolonged activation of the HPA axis (due to chronic stress) has been linked to increase risk of GI disorders such as Crohn’s Disease, coeliac disease , IBS (these disorders are associated with a reduction in ‘good’ bacteria’ )
what is the HPA axis?
controls reactions to stress and regulates many body processes, including digestion, immune responses, mood and emotions, sexual activity, and energy storage and expenditure
what was the impact on stress in germ-free studies?
- Increase release of stress hormones in germ-free mice (therefore prolonged HPA axis activation)
- In both mice and human studies, it’s been repeatedly demonstrated that the positive use of probiotics and a healthy gut-friendly diet improve stress levels
what was the impact on depression and anxiety in germ-free studies?
- Germ free mice exhibited significant increases in anxiety-like behaviour.
- One study implanted microbiota from patients with major depressive disorder into germ-free mice which then exhibited depressive like behaviours.
- Human studies have also demonstrated that people suffering from mental disorders (inc. depression, anxiety & psychotic disorders) are more likely to have a disrupted microbiome
- Probiotic treatments showed improvement in mood and reduced distress levels in 30 days
- Gut related diseases such irritable bowel syndrome (IBS) and inflammatory bowel disease have shown to increase likelihood of experiencing a mental health disorder
psychological responses to stress?
anxiety, worry, mood changes, restlessness
does CNS have direct contact with the outside world?
The CNS does not have direct contact with the outside world – it relies on the PNS to carry messages to and from the CNS
what neurons do the somatic nervous system contain?
Contains sensory neurons and motor neurons
define homeostasis
Homeostasis in a general sense refers to stability or balance in a system. It is the body’s attempt to maintain a constant internal environment.
what happens when you need to react to a stimuli very quickly?
Sometimes we need to react so quickly that there is no time for conscious thought - these unconscious, automatic responses are reflexes involving contraction of skeletal muscles – they occur in the same way each time, and do not require learning
what is a spinal reflex an example of?
The spinal reflex is an example of a polysynaptic reflex arc (involves more than one synapse, ie. S-I-M). The other type is a monosynaptic, like a knee-jerk reaction.
what are the two types of effects neurotransmitters have?
Inhibitory or Excitatory
what is an AP?
an electrical impulse that travels down the axon of a neuron
what do excitatory neurotransmitters do?
Excitatory neurotransmitters stimulate postsynaptic neurons to perform their functions (increases likelihood of firing an AP)
what do inhibitory neurotransmitters do?
Inhibitory neurotransmitters block, prevent, or suppress postsynaptic neurons from firing an AP
what happens if there is low levels of GABA?
Low levels of GABA = hard to inhibit heightened awareness and activity therefore causing anxiety
what are the two main neuromodulators?
DOPAMINE and SEROTONIN
what are the psychological stress responses?
- eustress
- distress
what are the physiological stress responses?
- fight, flight, freeze response in acute stress
- cortisol in chronic stress
does the body know the difference between eustress and distress?
the body does not recognize the distinction between eustress and distress
All stressors produce a non-specific stress response
Whether a stressor involves eustress or distress, our body undergoes virtually the same physiological changes, (E.G. increased heart rate and breathing rates)
[ie. Both involve activation of sympathetic NS]
how did Hans test his GAS model?
Hans used rats
He exposed them to a lot of stress – constantly pulling their tails
Looking at the long-term effects of stress…
*Most of Selye’s research was done with rats that were exposed to a variety of stressors such as painful tail-pulling, prolonged exposure to heat or cold, mild electric shocks, bacterial infections, strenuous exercise and forced restraint.
what is the middle line in the GAS model?
Middle = normal resistance to stress (this is a typical pattern of humans)
what did Hans observe when testing rats for the GAS model?
Observations:
*adrenal glands were enlarged, stomach ulcers developed, weight loss occurred and there was a shrinking of vital glands of the immune system (such as the lymph glands).
*On the basis of these observations, Selye concluded that stress is a condition that is non-specific, and which can be brought on by either internal or external stressors.
And then compared their organs (stressed vs. non stressed)
Deteriorated organs
what happens after these strategies in the transactional model?
Following these strategies, we may re-appraise the situation depending on what resources may become available
what strategies should be used in stressful situations?
Many stressors and stressful situations are actually quite complex, so both approach and avoidance strategies may be used for coping.
