U3A1 - How does the nervous system enable psychological functioning?

natural transmission

sensory - afferent
motor - efferent

sensory neurons

• somatic ns

• carry/relay sensory information from sensory receptors in the body to the spinal cord

• can feel texture and feeling like the feeling of fur when petting a dog

interneuron

• transmits info within the central ns

• relays messages between sensory and motor neurons within central ns

motor neurons

• somatic ns

• carry and relay motor info from the spinal cord muscles for voluntary bodily movements

central nervous system key functions

transmission and reception of the neural information to and from the peripheral nervous system, brain, spinal cord

central nervous system brain

• involved in organising, interpreting and integrating neural information

• any process that involves perception, memory and decision making are a function of the brain

central nervous system spinal cord

• extends from the base of the brain down the length of the spine

• primarily acts as a relay station between the brain and peripheral nervous system

peripheral nervous system

• somatic

• autonomic, parasympathetic, sympathetic

• enteric

somatic nervous system

carries sensory info to the central nervous system and motor information from the cns to initiate the voluntary movements

autonomic nervous system

• carries neural messages between the cns and internal muscles, organs and glands

• self regulating in controlling involuntary and autonomic functions

parasympathetic and sympathetic in autonomic nervous system

• both active at the same time however one system is usually dominant at any given time

• sympathetic dominates/more active during emotional arousal

• parasympathetic is dominant/more active during rest and digestion

parasympathetic nervous system

• calms body down after arousal

• maintains homeostasis

sympathetic nervous system

prepares body for actions by activating visceral muscles, organs, and glands for vigorous activity or to deal with a stressful or threatening situation

enteric nervous system

• controls the digestive system, directly

• two way connection with cns, working together to control the digestive system

• completes some functions independently of the brain

enteric nervous system roles

• detecting the physiological condition of the gastrointestinal tract

• integrating info about the state of the gastrointestinal tract

• controlling gut movements

• nutrient management

• regulating gastric secretions

• interacting with the immune and endocrine systems

conscious response

• a reaction to a sensory stimulus that involves awareness

• brain and spinal cord involved

• usually voluntary/intentional

• writing, sitting down, dancing, kicking

conscious response steps

• sensory neurons carry the sensory information of seeing something to the spinal cord

• interneurons in the spinal cord sends information to the brain

• the brain would process this information as a voluntary, conscious response

• the brain sends a neural message to the skeletal muscles so that she can do the action via motor neurons

unconscious response

• a reaction to a sensory stimulus that does not involve awareness

• only the spinal cord involved

• involuntary

• heart rate

spinal reflex

• an unconscious, involuntary process that serves an adaptive function to prevent damage and improve survival

• instead of sending the info all the way to the brain before the movement occurs it crosses over via interneurons in the spinal cord to enable motor neurons to activate the reflexive response

• quickly removing hand from a hot pan

unconscious response steps

• sensory neurons carry the sensory info of feeling extreme heat at the hand to the spinal cord

• interneurons in the spinal cord send/relay a signal via motor neurons to initiate an automatic/unconscious motor response of moving hand away from the heater

neurons

an individual nerve cell that is specialised to receive, process, and/or transmit info, acting as the primary functional units of the nervous system

dendrites

an extension of a neuron that has receptor sites to detect and receive neurotransmitters from other neurons

axon

a single tubelike extension that transmits neural information away from the cell body to axon terminals

axon terminals

store and release neurotransmitters to other neurons

synaptic transmission

the process of neurons communicating with other neurons

key structures for synaptic transmission

synaptic gap, synaptic neurons, post synaptic neurons

synaptic gap

the gap between neurons

synaptic neurons

neurons that release the chemicals into the synapse

post synaptic neurons

the neurons that receive the chemicals from the synapse

synapse

• where synaptic transmission occurs

• axon terminals of pre synaptic neurons

• synaptic gap

• the dendrites of the post synaptic neurons

neurotransmitters

chemicals released by a pre synaptic neuron to send signals to the post synaptic neuron

neurotransmitters role, target, speed of action, examples

• to transmit chemical signals to the adjacent neuron

• a single post synaptic neuron

• fast acting

• glutamate, GABA

neuromodulators

type of neurotransmitters that alter the strength of a neural transmission by increasing or decreasing the responsiveness of neurons to neurotransmitter signals

neuromodulators role

to alter the neural transmission of neurons by controlling the synthesis and release of neurotransmitters

neuromodulators target, speed of action, examples

• broad areas, groups of neurons

• moderately slow but last longer

• dopamine seratonin

GABA

• primary inhibitory neurotransmitter

• supresses or slows down post synaptic neuron activity, decreasing the likelihood of firing

• essential in maintaining neurotransmission at an optimal level

glutamate!!

• primary excitatory neurotransmitter

• enhances information transmission by making post synaptic neurons more likely to fire

• essential in the formation of long term memory and learning

glutamate and GABA together

• the inhibitory action of GABA counterbalances the excitatory activity of the glutamate and vice versa

• consequently, GABA and glutamate have important roles in regulating CNS arousal

dopamine

• excitatory or inhibitory effect on neurons

• the brain has several dopamine producing areas and neural pathways, known collectively as dopaminergic systems

• reward seeking behavior, coordinating movements

reward seeking behavior - dopamine

• the release of dopamine results in feelings of pleasure and euphoria

• dopmaine is released when we perform certain behaviors leading to a desire to repeat the behavior

• good for reward based learning

• can be harmful with gambling and illicit drugs which can lead to harmful additions

• high levels is linked to hallucinations an delusions in schizophrenia

coordinating movements- dopamine

• neurons in substantia nigra, midbrain produce dopamine which travel to the primary motor cortex to coordinate muscle movements

• when neurons damaged it results in slower, fewer and/or irregular dopamine messages about voluntary motor activity being sent to other muscles

• results in extreme muscle rigidity and stiffness, parkinsons

seratonin

• inhibitory effect

• produced in the brainstem and travels through the serotonergic system

• mood stabiliser, sleep wake cycles

mood stabiliser - seratonin

• allows us to feel calm and have a stable mood

• low levels are associated with mood disorders such as depression, anxiety disorders like OCD

sleep-wake cycles - serotonin

• works with the pineal gland to produce melanin

• increased levels of serotonin reduces the amount of rapid eye movement in sleep

synaptic plasticity

the ability of the synapse to change over time, changing its structure and function by rewiring itself

long term potentiation (LTP) definition

long lasting strengthening of synaptic connections

how does ltp occur

repeated stimulation by neurotransmitter between pre and post synaptic neurons

what does long term potentiation look like

1. increase in the amount of neurotransmitters

2. greater effects of neurotransmitters at the receptor sites

3. result in sprouting and rerouting

long term potentiation role in learning

the more we use the info being remember the more the LTP process strengthens the pathway, making it easier to retrieve that information

long term depression definition

long lasting weakening in the strength of synaptic neurons

how does long term depression occur

lack of stimulation by neurotransmitter between pre and post synaptic neurons

what does long term depression look like

1. neurons being less responsive to neurotransmitters

2. pruning

role of long term depression in learning

• enables old memories or unused connections and pathways to be cleared out

• may allow us to connect our thinking when solving a problem or to adjust our movements when learning a new motor skill

sprouting

• the growth of additional axons or dendrites to enable new connections with the other neurons

• enable increased and more flexible neural connections

rerouting

in response to damaged synaptic connections, healthy neurons develop alternate neural pathways to compensate for the damage and restore brain functioning

pruning

the elimination of weak, ineffective, unused synapses and therefore connections to other neurons to encourage increased efficiency of neural communication

stress

a state of psychological or physiological arousal produced by internal or external stressors that are perceived by the individual as challenging or exceeding their ability to cope

stressor

a stimulus that contributes to stress

internal stressor

• originates within the individual

• personal problem that causes concerns about the potential consequences

external stressor

• originates outside of individual from situations and events in the environment

• having too much homework

acute stress

• stress that lasts for a relatively short time

• body can bounce back quickly

• can be beneficial to help us deal with challenges

• for example, waiting for an exam to start

• fight, flight, freeze

fight flight freeze response

• an involuntary physical reaction that occurs in response to a sudden and immediate threat, helping us deal with the threat at hand and minmise harm

fight flight response

• confronting and fighting off threat

• escaping and running away to safety

• when we response by fighting or fleeing a stressor the sympathetic nervous system is dominant over parasympathetic

freeze response

• keeping absolutely still and silent, avoiding detection

• both sympathetic and parasympathetic ns are active but parasympathetic more dominant

• conserves energy until the threat has passed or the organism can act

chronic stress

• stress that continues for a prolonged period of time

• likely harmful for psychological and physical health

• can be debilitating and overwhelming

• for example social isolation and loneliness

cortisol

• a stress hormone produced by the adrenal glands

• acts more slowly and is longer lasting than adrenaline and noradrenaline

cortisol in chronic stress

• keeps body at an elevated level of arousal

• energises the body by increasing energy supplies and enhancing metabolism

• diverting energy from non essential bodily functions such as digestion and immunity

excessive amount of cortisol over a prolonged time

• impaired immune system functioning

• increased vulnerability to disease and infection

• slow healing

• psychological problems such as impaired cognitive performance