Nervous Systems Flashcards
(92 cards)
1
Q
central nervous system
A
brain and spinal cord
Processes info received from our internal and external environment and activates appropriate responses
2
Q
brain
A
a complex structure that receives and processes sensory stimuli from the body and coordinates responses, including voluntary movements, emotions and conscious thought.
3
Q
spinal cord
A
dense bundle of nerve tissue that runs from the brainstem to the lower middle section of the spine
Two major functions:
- Receive sensory information from the body (via the PNS) and send to the brain for processing
- Receive motor information from the brain and send it to body (via the PNS), to control muscles, glands, organs
4
Q
damage to the spinal cord
A
If the spinal cord is severed, the somatic nervous system below the point of severance becomes paralysed because the “bridge” between the CNS and the PNS can not be crossed
- Such damage has permanent consequences because the nerves in the spinal cord can not regenerate (grow back)
5
Q
Peripheral Nervous System
A
the entire network of nerves located outside the CNS (autonomic and somatic).
- carries messages between the CNS and the muscles, organs and glands throughout the body.
6
Q
somatic nervous system (def, sensory function and motor function)
A
carries sensory (afferent) info to the CNS and motor (efferent) info to the body
7
Q
autonomic
A
is a sub-division of the peripheral nervous system that controls the body’s internal environment in an autonomous or self-regulated manner.
occurs without conscious/voluntary effort
E.g digestion, heart rate, respiration
8
Q
sympathetic
A
Activates internal muscles, glands and organs to prepare the body to deal with vigorous activity or a stressful/threatening situation
Activated by a stressor or fear stimulus
- Enhances survival by producing an immediate response –“fight or flight”
9
Q
parasympathetic nervous system
A
In times of minimal stress and in the absence of threat, helps to maintain the internal body environment in a steady, balanced state
Counterbalances the activities of the sympathetic system.
Restores the body to a state of calm (homeostasis)
10
Q
enteric
A
A subdivision of the autonomic nervous system; it consists of nerve cells lining the gastrointestinal tract and controls the digestive system
11
Q
conscious response
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any response that requires awareness
The response will usually be a voluntary, ‘intentional’ reaction
E.g scratching an itch, throwing a ball etc
12
Q
unconscious response
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any response that does not require awareness
It is involuntary, unintentional, and automatic and we cannot ordinarily control its occurrence
E.g shivering, sneezing, spinal reflex
13
Q
spinal reflex
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An unconscious, involuntary and automatically occurring response to certain stimuli without any involvement of the brain
14
Q
steps of spinal reflex
A
Eg: touching a sharp object
- sensory receptors respond to the stimulation
- send message that is carried by the sensory neurons to interneurons in the spinal cord
- interneurons in the spinal cord relay the message to motor neurons
- motor neurons carry the message along a motor pathway to the muscles causing a withdrawal reflex. The hand is moved away before pain is perceived
- While the spinal reflex occurs, sensory neurons are also carrying the message further up the spinal cord to the brain
- The message is received in the brain (the area that processes this type of sensory info) and pain is perceived
15
Q
neurotransmitters
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A chemical substance produced by neurons that carries messages to other neurons or cells within the nervous system, including; muscles, organs and glands. (Excitatory and Inhibitory)
16
Q
excitatory neurotransmitter
A
increase the likelihood that the post-synaptic neuron will fire an action potential or neural impulse
E.g Glutamate
17
Q
Inhibitory neurotransmitter
A
decrease the likelihood that the post-synaptic neuron will fire an action potential or neural impulse
E.g GABA
18
Q
glutamate
A
the primary excitatory neurotransmitter in the nervous system and is associated with enhanced learning and memory
19
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GABA
A
the primary inhibitory neurotransmitter
fine-tunes neurotransmission in the brain and maintains neurotransmission at an optimal, or ‘best possible’, level.
Associated with anxiety, specific phobias and Parkinson’s disease
20
Q
Glutamate and learning
A
stimulates connections between neurons.
Glutamate is released when a neural pathway associated with an experience is activated or stimulated.
E.g: as you read and form a memory, glutamate will be released in the neural pathway associated with this concept in your brain.
Each time you retrieve this memory, this pathway will probably be strengthened and if you don’t this neural pathway will probably become weaker over time
21
Q
agonist
A
mimic the effect of a neurotransmitter. E.g. a GABA agonist may make it MORE likely that GABA inhibits neurotransmission
22
Q
antagonist
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slow down the effects of a neurotransmitter. E.g.
a GABA antagonist will reduce its inhibitory effect
23
Q
neuromodulator
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a subclass of neurotransmitters that alter the strength of neural transmission, by increasing or decreasing the responsiveness of neurons to neurotransmitter signals.
E.g Dopamine and serotonin (can work together)
24
Q
dopamine
A
a multifunctional neurotransmitter with both excitatory and inhibitory effects that is involved in many CNS functions such as pleasure, movement, attention, mood, cognition and motivation.
Dopamine is a neuromodulator because it reinforces the neural activity in regions of the brain associated with these functions
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Dopamine and the reward pathway
The reward pathway refers to a group of structures in the brain that are activated by rewarding or reinforcing stimuli
Controls our responses to natural rewards e.g food, sex, social interactions, and an important determinant of motivation.
When we are exposed to these rewarding stimuli, the brain increases the release of dopamine along this reward pathway in the brain, which modulates the brain activity of the structures along it.
The more dopamine released within the reward centre, the more a stimulus is sensed as a reward
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influence of dopamine - thirst
Dopamine release is coupled with the gulping motion and drinking behaviour (drinking is a learned behaviour)
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influence of dopamine - hunger and eating
The consumption of food releases dopamine and gives us feelings of pleasure, therefore increasing our chances of eating food the next time we experience hunger
The brain receives signals from several hormones that indicate when food is needed or not. These signals modify dopamine output from the brain’s reward pathway, controlling our motivation for food
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influence of dopamine - addiction
Whenever we see a reward worth chasing, our brain produces higher levels of dopamine, motivating us to complete the task, no matter how unhealthy or difficult the task might be.
Theory suggests that most addictions are caused by the brain’s inability to produce dopamine naturally without the behaviour or the substance that someone is addicted to
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seratonin
an inhibitory neurotransmitter that also acts as a neuromodulator.
In the brain, it modulates virtually all human behavioural processes, (e.g. mood, perception, reward)
The serotonin pathway originates in the brainstem and extends to almost all areas of the cerebrum including the cerebral cortex
30
influence of serotonin - mood
- serotonin levels are high = mood improves
- However, there are a lot of other chemical processes happening in the body, so it is difficult to establish a cause-and-effect relationship.
balanced serotonin levels = calm, focused, happy and stable moods
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influence of serotonin - sleep
- lower levels of serotonin = disruptive rhythm of being awake and asleep
- Research generally shows that if the brain lacks serotonin, a person will have a reduced pressure to sleep when required, thus increasing restlessness and wakefulness when they should be sleeping
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influence of serotonin - aggression and impulsivity
- higher serotonin level = people waiting longer for rewards, thus reducing impulsivity.
- Research indicates that low levels of serotonin in the brain can affect communication between specific structures within the limbic system responsible for regulating emotions, increasing aggressive and violent behaviours
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learning
involves the acquisition of new information, behaviour or abilities through experience.
For learning to have occurred, the new knowledge or skill must be retained in memory
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Herbs rule
HERBS RULE = NEURONS THAT FIRE TOGETHER, WIRE TOGETHER
- When a neurotransmitter is repeatedly sent across the synaptic gap, pre and postsynaptic neurons are repeatedly activated at the same time
- This changes the structure of the synapse, strengthening the connection between these two neurons at the synapse
- When this connection is strengthened, they are more likely to fire together again, and their signals are more efficient in the future
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long term potentiation
the long-lasting strengthening of synaptic connections, resulting in enhanced or more effective synaptic transmission
The effect of LTP is to improve the ability of two neurons to communicate with each other
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long term depression
the opposite of LTP.
LTD is a long-lasting decrease in the strength of synaptic transmission
This results from lack of stimulation of pre and postsynaptic neurons, or prolonged low-level stimulation
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sprouting
The creation of new extensions on a neuron allows it to make new connections with other neurons. This occurs through the growth of nerve endings (‘sprouts’) on axons or dendrites
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rerouting
New connections are made between neurons to create alternate neural pathways.
These alternate ‘routes’ may be entirely new neural pathways or connections to other pathways in the brain
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pruning
The elimination of weak, ineffective or unused synapses (and therefore connections to other neurons).
Experience determines which synapses will be retained and strengthened and which will be pruned
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stress
a psychobiological process,
a state of mental, emotional and physiological tension in response to a stressor
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stressor
any event that causes stress or is perceived as a threat and a challenge to our ability to cope
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internal stressors
originates within an individual
can be both psychological and biological
E.g: Physical pain, having high expectations of yourself, feelings etc
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external stressor
originate outside of an individual including environmental and sociocultural events
E.g: Loud noises, extreme temperatures, loss of significant relationships etc
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acute stress
occurs because of a sudden threat and lasts for a relatively short time. E.g sitting an exam
- Acute stress can have negative effects such as elevated blood pressure or reduced motivation to persist with a task, but it can also be beneficial (e.g. releasing adrenaline).
- linked with the FIGHT-FLIGHT-FREEZE response
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chronic stress
stress that continues for a prolonged period of time.
- It involves ongoing demands, pressures and worries that are constant and long-lasting.
- Chronic stress is linked with the release of cortisol, and larger effects on both our psychological and physical wellbeing
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acute stress - fight, flight, freeze
Without our awareness or conscious control, we respond to an immediate threat by activating the fight-or-flight-or-freeze response.
It is an acute physiological stress response and is considered to be adaptive, in that it minimises possible harm, and enables us to deal with the stressor most effectively by instinctively adopting one of three options.
In fight or flight responses, you experience similar physiological responses, such as increased heart rate, sweaty palms and dilated pupils as a part of an acute stress response. This is because the fight or flight response is activated by the sympathetic subdivision of the autonomic nervous system
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benefits of increased heart rate, breathing rate and blood pressure
To quickly transport oxygenated blood to the muscles in our extremities to prepare them for action
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benefits of dilated pupils
to increase the amount of light entering the eye to potentially see more clearly
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benefits of slowed digestion rate and decreased salivation
to divert energy to where it is needed most, such as the muscles in our extremities
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benefits if increased sweat production
To keep the body cool when increased energy is expended
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benefits of increased muscle tension
to prepare our muscles for action
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acute stress - freeze response
thought to have adaptive value.
When attacked by a predator, some animals freeze or ‘play dead’.
It is also thought that freezing is a way for the nervous system to prepare to immediately shift into fight or flight action.
Freezing is not considered to be a passive state but rather a parasympathetic brake on certain body systems
53
chronic stress - cortisol
In times of prolonged and chronic stress, another stress hormone called cortisol is produced and released from the adrenal cortex, the outer layer of the adrenal glands.
Cortisol allows the body to continue to stay on high alert over long periods of time and regulates a wide range of processes throughout the body, including metabolism and the immune response.
It is released directly into the bloodstream and transported throughout the body
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benefits of cortisol
- boosting our energy levels
- heightening our alertness
- increasing the body’s ability to repair tissue
- diverting energy from non-essential bodily functions
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negative implications of cortisol
Cortisol suppresses the immune system, making us more susceptible to colds and contagious illnesses.
When we experience ongoing chronic stress, our risk of cancer and autoimmune diseases, as well as psychiatric conditions such as anxiety and depression, increases
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The Gut-Brain Axis
refers to the connection between the central nervous system (CNS) and the enteric nervous system (ENS).
this relationship is bidirectional
E.g, feeling "sick to your stomach -> emotions affecting our gut
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communication between the ENS and the brain
- enteric NS communicates with the brain via afferent (sensory) nerves (to the brain) and efferent (motor) nerves (from the brain).
- occurs via the vagus nerve and gut microbiota.
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vagus nerve
connects the brain (CNS) to organs within the ANS
afferent info is sent via the vagus nerve from the gut to the brain, e.g you are full, stop eating
efferent info is sent via the vagus nerve from the brain to the gut, e.g start secreting acid, food coming
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gut microbiota
includes over 1000 types of microbe species that are in our gut
these microbes get nutrients from the food we eat and can produce energy, nutrients and in some cases, neurotransmitters
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gut-brain axis and GABA
Some microbiota produce GABA.
less of this certain microbiota = less GABA
less GABA = more anxiety + depression symptoms
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stress, gut microbiota and our nervous system
- stress causes changes in gut microbiota and deficiencies in certain bacteria, which have been linked to anxiety and depression
- specific gut microbiota associated with stress has been shown to increase anxiety-related behaviours
- stress exposure early in life or in adulthood can change an organism’s microbiota composition
- the types and variety of microbe populations we have in our gut can shape our stress responsiveness
- treatment with healthy microbiota can reduce anxiety-like behaviour and reduce stress responsiveness in humans and mice.
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Selye's GAS Model
- Selye – stress is a non-specific condition, brought on by internal or external stressors and can produce the same reaction (sympathetic nervous system activated)
- Selye’s research was conducted with rats and he observed that despite the variety of stressors rats were exposed to, the physiological arousal pattern was generally the same
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Selye emphasised 2 elements when describing GAS
- It is non-specific, meaning it is the same irrespective of the type of stressor the organism is exposed to.
- It is identical within all members of a species, in his case rats.
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stage 1
- Alarm Reaction – occurs when the person (or animal) first becomes aware of the stressor.
Experienced in 2 stages: shock and countershock
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stage 1: shock
the body’s ability to deal with the stressor falls below the normal level. The body reacts as if it were injured, body temperature drops. People are most vulnerable in this stage (fainting, heart attacks)
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stage 1: counter shock
the sympathetic nervous system is activated (fight-flight response), body’s resistance to stressors increases. Adrenaline is released into the bloodstream, heart and respiratory system rates increase = more energy for muscles (glucose, oxygen)
If the stress is not dealt with immediately and continues, we enter the Resistance Stage
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stage 2
Resistance – the body’s resistance to the stressor rises above normal
- Intense arousal of alarm reaction diminishes, and physiological arousal remains above normal. All unnecessary physiological processes are shut down – (digestion, menstruation, testosterone production)
- Cortisol released into the bloodstream – energises the body
- However, cortisol weakens immune system activity
- Ability to deal with the initial stressor in this stage increases, however resistance to other stressors may decline (illness/disease).
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stage 3
Exhaustion –
- Due to the prolonged stress, the body’s resources have been depleted and it becomes vulnerable to diseases and mental disorders
- extreme fatigue, high levels of anxiety, nightmares, impaired sexual performance, hypertension, gastrointestinal problems and heart disease
- ‘Wear and tear’ due to immune suppression and prolonged levels of cortisol in the bloodstream as cortisol interferes with the body’s ability to fight disease and protect itself
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scARE
Shock
Countershock
Alarm reaction
Resistance
Exhaustion
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strengths of the GAS model
- The model suggests a predictable pattern of responses that can easily be tested in a lab, identifies various biological processes that occur as a part of the stress response (hormone secretion and immune system depletion)
- It is one of the first theories to suggest that stress can weaken the body's resistance to illness.
- There is research and evidence to suggest that the three stages of GAS exist and that the body's non-specific response to a stressor is a physiological reality (at least in rats).
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limitations of the GAS model
- Humans and rats are physiologically different. E.g, human stress responses tend to be more complex and variable. Therefore, Selye's GAS model cannot be simply generalised to humans
- It does not account for individual differences in stress responses. E.g, many different types of disorders are associated with high-stress levels, such as hypertension (high blood pressure), post-traumatic stress disorder and major depression.
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Lazarus and Folkman's transactional model of stress and coping
- Stress involves an encounter (transaction) between an individual and their external environment, and the stress response depends upon the individual’s interpretation (appraisal) of the stressor and their ability to cope with it
- The environment can influence the individual, the individual can influence the environment
- When there is an imbalance between a person’s appraisal of the demands of the situation and their estimation to meet those demands = stress response
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primary appraisal
In the primary appraisal, individuals evaluate/judge the significance of the situation/event
a)Make a decision about the event: is it irrelevant, benign-positive or stressful
b)If the situation is stressful, additional appraisals take place:
- Harm/loss: how much damage has already occurred
- Threat: what harm/loss may occur in the future
- Challenge: assessment of personal gain/growth from the situation
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secondary appraisal
In the Secondary Appraisal, individuals evaluate their coping options/resources, and options for dealing with the stressful situation
For example, if somebody has decided that an upcoming SAC is a stressful situation, their coping resources are their teacher, studying, etc.
Coping options and resources can be internal or external
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Strengths of L&F transactional model of stress and coping
- the model acknowledges the psychological determinants or causes of the stress response
- it emphasises the personal nature and individuality of the stress response, accounting for why individual responses to an event vary widely
- it suggests that because stress involves an interaction with the environment, the individual has an active role in their own stress response and can therefore learn to respond and manage it
- the model allows for the fact that stressors and the circumstances under which they occur can change over time and that our thinking about a stressor and our response to it can also change
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Limitations of L&F transactional model of stress and coping
- It is difficult to test through experimental research because of the subjective nature of individual responses to stress
- Individuals may not always be consciously aware of all the factors causing them stress or the thought processes that take place internally when experiencing stress
- It does not allow for individual variation in progression through its stages, as primary and secondary appraisals have been found to interact with one another and often occur simultaneously
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coping
a process involving cognitive and behavioural efforts to manage specific internal and/or external stressors that are appraised as taxing or exceeding our resources in a stressful situation
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coping strategy
a specific method, behavioural or psychological, that people use to manage or reduce the stress produced by the stressor.
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whether the coping strategy works or not is influenced by 2 factors
- coping flexibility
- context-specific effectiveness
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coping flexibility
The ability to effectively adjust one’s coping strategies according to the demands of different stressful situations
The more flexible our selection of coping strategies = more effective coping and greater wellbeing
Includes the ability to:
- Recognise whether a flexible coping approach is suitable for a specific situation
- Recognise when coping strategies are not effective and discontinue it
- Implement an alternative coping strategy when required
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individuals with high coping flexibility
quickly recognise and adjust their coping strategies if they are ineffective. These individuals tend to use a wider variety of coping strategies across situations, and match the strategies to the demands of the situation
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individuals with low coping flexibility
tend to rely on the same, limited coping strategies across different situations, and persist with them, even if they are ineffective. Essentially, these individuals are not flexible and are predictable when dealing with stress
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context-specific effectiveness
when there is a match between the coping strategy that is used and the stressful situation
- Eg: Taking positive action to deal with a stressor in some contexts would be effective, whereas wishful thinking or mentally distancing themselves from the stress may be effective in other contexts
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approach and avoidance strategies
‘approach’ and ‘avoidance’ refer to the orientation or focus of an individual’s activity either towards or away from the stressor. The aim of both approach and avoidance strategies is to reduce stress levels and increase the ability to cope, but the method by which this is achieved differs.
85
approach strategies
involve confronting the stressor directly
E.g
- seeking advice from an expert
- talking through your problems with a friend or family member
- accepting responsibility for a problem or reframing a situation
- developing a plan to increase your sense of control
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avoidance coping strategies
involve evading a stressor and dealing with it indirectly
E.g
- procrastination
- napping or oversleeping
- substance use or abuse
- denial
- use of distractions such as television or computer games.
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approach strategy benefits
- approach strategies are generally considered to be more adaptive and effective than avoidance strategies
- people who rely more on approach strategies to cope with a stressor tend to experience fewer psychological symptoms and can function more effectively than people who rely more on avoidance strategies
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approach strategy limitations
- initially or in the short term, approach strategies may increase stress levels while the individual is directly engaged with the stressor and its causes
- an approach strategy may require a lot of the individual's energy and focus to deal with the stressor, which means they might neglect other aspects of their lives
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avoidance strategy benefits
- it allows you to conserve energy to focus on other stressors that can be changed
- ignoring a stressor for a couple of days while focusing on other things can provide 'time out' from a stressor while minimising potential stress from another source
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avoidance strategy limitations
- avoidance strategies tend to be maladaptive
- excessive reliance on avoidance strategies tend to be associated with several negative consequences, e.g increased vulnerability to mental health problems and stress-related physical problems, such as hypertension and cardiovascular disease
- long-term use of avoidance strategies can also contribute to other problems, e.g delinquency, socially inappropriate behaviours and substance use
- the strategies tend to only be helpful in the short term, and their long-term use can prevent people from responding to stressors in constructive ways
- delaying actually dealing with a stressor can also have negative consequences and might be detrimental when action is needed
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exercise as a coping strategy
- Physical activity that is usually planned and performed to improve/maintain physical condition
- Physical activity (aerobic is best) = good mental health/wellbeing
- Exercise increases energy demands – uses up the stress hormones (cortisol) in the bloodstream
- Endorphins are produced during exercise, this (with serotonin and dopamine) improves mood
- Regular exercise reduces the reactivity of the sympathetic nervous system
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why is exercise an avoidance strategy?
exercise is usually an avoidance strategy because it does not directly deal with the stressor a person is facing. However, this is not the case when the stressor is exercise related. E.g wanting to lose weight or training for a marathon
