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NERVOUS SYSTEM FUNCTIONING, STRESS AS AN EXAMPLE OF PSYCHOBIOLOGICAL PROCESS
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what are the functions of the Nervous System
PRO
receiving - receiving sensory information from the internal and external environment
processing - processing sensory information (usually occurring in the brain)
organising - organising and coordinating an appropriate response to sensory information (action)
what are the 2 major divisions of the Nervous System
central nervous system
peripheral nervous system
both systems contain different structures and components that work together to create psychological and physiological responses to sensory information
what is the central nervous system
the system of the body that comprises of the brain and spinal cord, where it is responsible for processing and coordinating a response to sensory stimuli
what is the role of the brain in the central nervous system
it is responsible for receiving, processing and interpreting information that is received from the body’s sensory systems. the brain allows for sensory information to be interpreted and form a response via sending motor messages to the rest of the body via the spinal cord to coordinate an appropriate response to sensory information.
what is the role of the spinal cord in the central nervous system
is it responsible for the communication between the brain and rest of the body via receiving sensory information from the PNS and transmitting sensory messages to the brain for further processing and interpretation as well as allowing motor messages from the brain to travel to the muscles, organs and glands of the body to coordinate an appropriate response to information.
what would happen if damage to the spinal cord where to occur
damage to the spinal cord would cause information to be unable to flow between the brain and the rest of the body, which may result in a loss of sensitivity to the body’s sensory systems and/or loss of motor control.
what is the Peripheral Nervous System
this PNS refers to all of the nerves outside of the CNS, extending from the brain and spinal cord to the rest of the body such as muscles, organs and glands. these nerves carry sensory information from the body’s internal and external environment to the CNS as well as carrying motor information from the CNS to the rest of the body due to its connection to the spinal cord.
what are the 2 subdivisions of the Peripheral Nervous System
somatic nervous system
autonomic nervous system
what is the role of the somatic nervous systems in the peripheral nervous system
it is responsible for sensing stimuli and controlling voluntary skeletal muscular movement, hence it having both a sensory and motor role.
sensory role - the sensory neurons will receive sensory information from receptors located all over the body and transmit this information to the CNS.
motor role - motor neurons will receive commands from the CNS and transmit this information to skeletal muscles to coordinate voluntary movements.
along what tracks of the spinal cord does sensory and motor information travel along
SAME
sensory information runs along the afferent (ascending) tracts of the spinal cord to the brain
motor information runs along the efferent (descending) tracts of the spinal cord
what is the role of the autonomic nervous system
it is responsible for the control of activity levels of organs and glands within the body that are essential for survival and are self regulating. this is done via motor messages being sent from the brain to the body’s smooth muscles to control activity levels and sensory messages from the activity to the muscles being sent back to the brain.
what are the subdivisions of the autonomic nervous system
sympathetic nervous system
parasympathetic nervous system
endocrine nervous system
what is the role of the sympathetic nervous system
it is responsible for allowing the body to experience heightened levels of emotion during vigorous physically activity and when we perceive a threat. this allows our body to be prepared for action by increasing the activity levels of some bodily systems and slowing down others as well as sending messages to the adrenaline glands to stimulate the release of adrenaline and and noradrenaline hormones into the bloodstream.
what does the sympathetic nervous system have control over
MOG
muscles - increasing heart rate, respiratory rate and blood pressure
organs - causing pupils to dilate and allow more light to enter the eye to improve vision
glands - cause sweat glands to perspire more
what is the role of the parasympathetic nervous system
is that it is responsible for keeping the body’s internal systems at a balanced and in a healthy state by maintaining regular levels of homeostasis and vital unconscious function.
what does the parasympathetic nervous system have control over
MOG
muscles - decreasing heart rate and respiratory rate
organs - causing pupils to constrict
glands - allowing digestion to return to normal and causing sweat glands to inhibit perspiration
what is a conscious response
it is a response that involves awareness to sensory information, as there has been communication between the brain and somatic nervous system to coordinate voluntary movement.
what is an unconscious response
is a response that the Autonomic Nervous System is responsible for. this is when there is control over the involuntary muscles that regulate activity levels of organs and glands that are usually self regulating without conscious control.
what is a spinal reflex
it is a reflex that occurs in the spinal cord and opperates independently from the brain where this response helps to aid our survival and make rapid responses to stimuli that may be dangerous.
why is a spinal reflex considered to be part of the somatic nervous system
is because of how skeletal muscles are used as part of a response
what are the 3 types of specialised neurons in a spinal reflex
motor neurons
sensory neurons
interneurons
what is the role and function of a neuron
neurons are the basic building blocks of the NS and are specialised to receive, process and transmit neural information in both a chemical and electrical form all around the brain and body.
what is the order in which neural information will travel from one neuron to another
at the pre-synaptic neuron, the action potential (neural impulse) will move to the soma in an electrical form → through to the axon which is surrounded by myelin sheath → to the axon terminal where the action potential will prompt the release of neurotransmitter vesicles to release neurons in the synaptic clef → which will bind to receptor sites on the post synaptic neuron and then prompt th electrical form of the neural impulse to continue to flow
what is a neurotransmitter
a chemical messenger that transmits neural information from one nueron to another
what is the synapse
a microscopic gap between 2 neurons that allows them to communicate with one another
what does the synapse consist of
the pre-synaptic neuron’s axon terminal, the synaptic cleft, and the dendrites that are located on the post-synaptic neuron
what is the role of a receptor site
to hold a specific shape that will allow for specific neurotransmitters to bind to and allow for the neural message to continue to flow from the synapse into the post-synaptic neuron
what process may excite or inhibit the post-synaptic neuron
if many neurotransmitters have binded to receptor sites, this may excite the post-synaptic neuron and make it more likely to fire an action potential, however if not enough specific neurotransmitters binded to specific receptor sites this may inhibit the likliness for an action potential to fire.
what does action potential refer to
the electrical neural impulse that travels along a neuron
what is the process of re-uptake
the process of neurotransmitters that have not binded to specific receptor sites on the post-synaptic neuron, being reabsorbed back into the pre-synaptic neuron to be stored for later usage
what are 2 types of neurotransmitters
glutamate - excitatory synapse
GABA - inhibitory synapse
what is glutamate
a primary excitatory neurotransmitter that is involved in high speed neural transmissions that allow for action potential to be more likely to fire.
what is the function and role of glutamate
its function is to increase the speed of the transmission of neural messages between neurons and it plays a large role in cognition, learning, memory, behaviour, movement and sensation
what is GABA (Gamma amino butyric acid )
it is the primary inhibitory neurotransmitter which is extensively found throughout the NS to help calm the body by slowing down the rate of neural transmission and action potential and counteracting excitatory neurons.
what would occur is glutamate overpowered GABA
if there was a higher concerntration of glutamate compared to GABA, the rate of neural transmission will become overstimulated and lead to an increase of heart rate, respiratory rate and blood pressure.
what are the features of neurotransmitters such as glutamate and GABA
both of these neurotransmitters are fast acting, localised (acting in a single synapse) and short lived
what are neuromodulators
they are another group of neurotransmitters that diffuse over large areas of the brain and can affect more than 1 neuron at a time, where they are slow acting, but create long lasting effects to the brain’s neurons and synapse
what are 2 types of neuromodulators
dopamine
serotonin
what is the role of dopamine
it is a neuromodulator that is involved in signalling that an award is available
when is dopamine released
when participating in activities that anticipate a reward such as
motivating behaviour - eg searching for food and water
learning new behaviours that will bring about a reward
attending to and remembering environmental cues that link to a reward
how is dopamine associated with movement
it is responsible for initiating movement towards a reward which is known as approach behaviour and can explain impaired movement sympotoms associated with Parkin’s disease
what is serotonin
it is a neuromodulator that is produced in the CNS and intestines and is involved in pain, sleep and mood regulation
what would occur if an individual has lower levels of serotonin
lower levels of serotonin can lead to mood disorders, anxiety, and sleep disorders
differences between neurotransmitter and neuromodulators
neurotransmitter
targets a single neuron
is released in the synapse
are chemicals that are released by a pre-synaptic neuron to be transmitted to a post-synaptic neuron (transmit to an adjacent neuron)
are fast acting, localised (acting in a single synapse) and short lived
neuromodulator
targets multiple neurons
not released in the synapse (can diffuse around large areas of the brain)
work slowly, but have longer lasting effects on the neurons and synapse of the brain
chemicals released by neurons to alter the effectiveness of neural transmission by controlling the synthesis(absorption) and release of neurotransmitters
plasticity
moveable, mouldable, plastic
learning
refers to the process of gaining new knowledge and skills which can cause a relatively permanent change in behaviour ( or behaviour potential ) due to an experience
memory
refers to an active information processing system where information is received, organised, stored and recovered when needed.
when does memory first begin
when you take in information through the senses that can be from either the internal or external environment. then the nervous system will convert this sensory information to impulses in electrochemical form to send to the brain for further processing, interpretation and storage.
what is Hebb’s rule
when one neuron activates another or ‘fire’ together they become more closely wired and ‘wire’ together
when one neuron activates another a change occurs at the synapse which causes the synapse to strengthen.
synaptic plasticity
when we learn something new and store it as a memory, a relatively permanent and stable connection between neurons is made. where specific changes to the synapse between neurons occur known as synaptic plasticity, and cause neural connections to either strengthen or weaken.
how is glutamate involved in synaptic plasticity
when learning something new and storing it as a memory, glutamate is released each time a neural pathway associated with an experience is activated. since glutamate is an excitatory neurotransmitter it stimulates the activity in the neural pathway to help make memory strong
what is an excitatory neuron
allows for an increase in speed of a neural impulses to travel between 2 neurons, allowing an action potential to be more likely to fire.
what are the types of changes that occur during synaptic plasticity
structural changes - involve sprouting, pruning, and rerouting, such as the growth and removal of dendrite spines and filigree appendages , and the number of receptor sites found on a post-synaptic neuron
physiological changes - such as the ability for the post-synaptic neuron to be excited by neurotransmitters eg via neuromodulators, and changes in the amount of neurotransmitters released
what are processes that are involved in synaptic plasticity
long term potentiation (LTP)
long term depression (LTD)
long term potentiation (LTP)
refers to long-lasting, relatively permanent strengthening of synaptic connections which result from repeated activation of the neural pathway. which leads to a long-lasting increase of excitability at the synapse and will not occur if insufficient stimulation is present
what are the changes that occur to the pre and post synaptic neuron during long term potentiation
more glutamate will be released into the synapse from the pre-synaptic neuron which allows for an increase of excitation in the post-synaptic neuron
repeated activation for a neural pathways always for the creation of more receptor sites on the surface of the post-synaptic neuron, which allows both the pre and post synaptic neuron to be able to transmit neural messages more efficiently
what is long term depression (LTD)
refers to a change between neurons that is long-lasting, and provides relatively permanent weakening of the synaptic connection between neurons, due to persistent weak stimulation of a neural pathway.
when does Long term depression occur
when the efficiency of synaptic transmissions between neurons are reduced
when messages sent from the pre-synaptic neuron are weak due to a reduced release of glutamate, causing action potential to be less likely to fire in the post-synaptic neuron
what role does long term depression play
helping to weaken and remove unused and unstimulated synapses (known as synaptic pruning), which helps the brain to become more efficient as it only contains synapses that are important for brain functioning
pruning
refers to the removal and weakening of unused and unstimulated synapses and neurons to fine-tune neural networks and help the brain to become more efficient
rerouting
refers to the establishment of new synaptic connections and neural pathways between an undamaged neuron that was once connected to a now damaged neuron, so this undamaged neuron connects to a new undamaged neuron
sprouting
refers to the growth of new dendrites spines on a post synaptic neuron, and the growth of filigree appendages on pre-synaptic neruons which lead to the creation of synaptic-genesis.
what is stress
stress is a psychobiological process, a state of mental, emotional and physical tension when perceiving something as a threat or challenging to the body’s ability to cope.
what are psychological symptoms the body experiences when under stress
expiring unique and subjective thought and emotions such as anxiety, fear, excitement and anticipation
what are some biological symptoms the body experiences when under stress
MOG
increased muscle tension, increase Hr,RR and BP
causing pupils to dilate
activate sweat glands to increase perspiration
what is a stressor
an object, event or person that is perceived as threatening or challenging, creating stress
how is stress motivational
stress encourages the body to take action and enhances the body’s chance of survival
what is an internal stress
factors that originate inside of the body, which can be both biological and psychological (psychobiological)
examples of biological internal stressors
these refer to stressors that affect your physical wellbeing, such as nutritional health, pain, illness and adequate sleep
examples of psychological internal stressors
these refers to stressors that affect your thoughts and behaviours due to a persons psychological mindset and expectations. this can cause people to experience feeling worried, anxious, having negative self talk and low self esteem, comparing themselves to others, and experiencing feelings of anger, fear or negative attitudes
what are external stressors
these are stressors that originate outside of the body such as the social ,cultural and physical environmental conditions that are often unable to be controlled
example of external stressors
daily pressure - meeting deadlines, conforming to society, conflicts
bullying / harassment
adjusting to new cultures such as schools, workplaces and countries
extreme hot or cold temperatures
global events eg pandemic
acute stress
is a form of stress where the body has an immediate response to a perceived threat which is often short lived and intense causing the body to becomes highly aroused. this can be caused by the demands and pressures of everyday life regardless of whether the stressor is challenging or threatening the body’s ability to cope
how is acute stress beneficial
acute stress can allow to body to become energised and motivated to take action and remain highly alert
how can acute stress lead to chronic stress
if a person is continuously exposed to the same or multiple different stressors for a prolonged period of time it can cause symptoms of chronic stress to from.
what is chronic stress
is the body’s response to a persistent and long-term stressor which can lead to both psychological and physiological harm. this can be caused by ongoing demands, pressures and worries about things we believe we do not have under control or feel as if it wont come to an end.
examples of how chronic stress can impact the body
chronic stress can not be as intense as acute stress but has detrimental effects to the body over a prolonged expose to a stressor, such as causing
suppression to the immune system
upsetting the digestive and reproductive system
increasing risk of heart attack and stroke
becoming more prone to psychological conditions such as depression, anxiety and other mental health conditions
constant feelings of unease, despair, and hopelessness
what is a stress response
a set of psychological and biological responses that automatically occur once the sympathetic nervous system is activate in response to perceiving a threat.
what is the fight-or-flight-or-freeze response
it is an adaptive and automatic bodily response that occurs without conscious awareness when the body detects a stressor, and helps to body to survive by acting in the most effective way possible
what is the fight response
this involves dealing with the stressor directly
what is the flight response
this involves evading or escaping the stressor
what is the freeze response
this involves the body becoming immobilised and minimising movement and vocal sound to avoid detection
how is the fight-or-flight-or-freeze response activated
this is activated once the sympathetic nervous systems becomes dominant over the parasympathetic nervous system, as signals are sent to the adrenal glands to stimulate the production and release of adrenaline (epinephrine), noradrenaline (norepinephrine) and cortisol hormones into the bloodstream to ensure the body experiences heightened alertness and that muscles are prepared for fast and powerful movement.
how does the freeze response differ to both the fight and flight response
the freeze response activates both the sympathetic and parasympathetic nervous system, whereas both fight and flight activate only the sympathetic.
sympathetic NS - becomes dominant when preparing the body to be able to spring into fast and powerful action
parasympathetic NS - becomes dominant when storing the body’s energy levels such as reducing HR, blood pressure, and muscle tension (through movement) and reducing vocalisation such as speech and sound
what is the role of cortisol in chronic stress
when a stressor persists and leads to body to believe it is still under threat over a prolonged period of time and leading to the development of chronic stress, the body releases a hormones known as cortisol from the adrenal cortex which causes the body to stay alert over long periods of time.
what are the benefits of cortisol
increases the body’s energy levels and increases levels of blood glucose
increases heightened alertness by producing more glucose in the brain
diverts energy from non-essential bodily functions such as digestion to allow for the body to conserve energy
increases the body’s ability to repair tissue
disadvantages from cortisol
high levels of cortisol found within the bloodstream over a prolonged period of time can be detrimental to the body such as
suppressing the immune system, causing you to become more prone to a cold and contagious illness
increasing risk of cancer and other autoimmune systems
increasing the risk of psychological conditions such as depression and anxiety
what is the Gut Brain Axis (GBA)
is a network of neural pathways that connect the CNS and ENS as biodirectional communication occurs through the gastrointestinal tract and brain.
how does biodirectional communication between the CNS and ENS occur
via the usage of the vagus nerve and gut microbiota
what does GBA include
CNS
ENS
sympathetic and parasympathetic branches of the ANS
gut microbiota
vagus nerve
what is the Enteric nervous system (ENS)
it is a branch of the autonomic nervous system, that consists of nerve cells that line the gastrointestinal tract, and control the activity of the digestive system
what type of neurons is the Enteric Nervous System made up of
200 - 600 million motor, sensory and interneurons
what are interneurons
nerve cells that are located in the spinal cord that connect motor and sensory neurons by relaying information between them and initiate an adaptive motor response without the input from the brain to allow for a quick response to stimulus.
how is the communication between the CNS and ENS biodirectional
as afferent sensory messages are sent from the ENS to CNS and efferent messages are sent from the CNS to ENS via the usage of the vagus nerve and gut microbiota
what is the role of the Enteric Nervous System
to control motility of the intestine (giving it ability to stretch and contract to move materials along the digestive tract)
allowing communication with the CNS primarily through the vagus nerve and gut microbiota
immune defence
regulating fluids and blood flow within the ENS
detecting nutrients
maintaining chemistry within gut (hormones, digestive enzymes)
what is the vagus nerve
is a nerve that connect the brain to organs that are within the autonomic nervous system via nerve fibres that directly link to organs such as the heart, lungs, intestines and oesophagus, which is control many crucial bodily functions such as heart rate, mood, digestion, and immune response
what is gut microbiota
it is a highly diverse and dynamic system of almost 100 trillion bacteria and other microorganims living within the human gastrointestinal tract, in which it has a symbiotic relationship with humans
how has gut microbiota evolved over time
gut microbiota has been able to evolve and respond to changes in the internal and external environment to maintain health and wellbeing
how can gut microbiota being influenced
via
change in diet
illness
antibiotic treatment
age
stress
genetics metabolism
how does gut microbiota play a role in biodirectional communication between the CNS and ENS
gut microbiota is involved in the production of neurotransmitters which ultimately allow for the biodirectional communication between the CNS and ENS to occur, whilst research has also found that neurotransmitters produced in the gastrointestinal tract has influence neural activity and cognitive functioning of the brain.