brain learning and motivation: neural communications Flashcards
typical neuron structure
neutrons are basic building blocks of nervous system
nucleus cell membrane dendrites sona *cell body Myelin sheath node of ranvier axon axon terminals
informaion passing through neutrons
information passes down neutron by electrical impulse
information is transmitted within neutrons
through axonal conduction
information transmitted between neutrons
through synaptic transmission
how they communicate
the neuron generates an electrical impulse that travels down the axon and into the axon terminals
3 main neuron types
sensory
motor
interneuron
purkinje neutron found by
costandi
Ramon V Cajal in 1899
neuron structure: soma
the ell body
neuron structure: dendrites
specialised receiving units that collect messages from neighbouring neutrons and send them on to the cell body
neuron structure: Axon
cunducts electrical impulses away from cell body to other neutrons muscles or glands
neuron structure: Myelin Sheath
series of fatty wrappers formed by Glial cells
surrounds axons of neutrons that communicate over long distances in nervous system
allow fast propagation of action potentials along those axons
MS
De-Myelination occurs
neuron structure: nodes of Ranvier
Gaps between the Glial cell wrappers of Myelin Sheath around axons
nodes are crucial to the speed of electrical impulses along Myelinated axons
electrical signal is slow even in Myelinated neutrons its around 1-91m per sec
the ways in which neutrons pass information
electrical impulses
chemistry
Myelinated neurons appearance
white matter
whitish appearing particles and paths in the brain
composed of Myelinated neurons in particular Axons
gray matter
the absence of myelination gray matter is: Dendrites cell bodies unMyelinated axons ...these are the nervous systems microcircuitry
Glial cells
act as a guide wire for growing neurons
provide a supportive scaffolding for mature neutrons
form Myelin Sheath and blood brain barrier
the blood brain barrier
protects the brain from:
noxious substances
some drugs
blood vessels in brain
selectively permeable barrier
have a protective lining
allows in nutrients but keeps out toxious substances
prescription drugs for brain conditions must be able to pass through barrier
Neuron communication: Axon membrane
Axon membrane is semi permiable so some chemicals can pass through freely others cat
When Axon membrane is stable there is an excess of positive ions on outside making a negative charge difference
recording voltage within a neutron
an electrode is inserted into axon
the other records from Axons outside
at rest a -70 millivolt different ewill be detected
at firing the voltage will shift slightly before returning to resting voltage
Neuron communications: electrical communications and voltage changes
when membrane is stimulated it deeplarises
and sodium ion channels open
this leads to an action potential
ion movement leads to an excess of positively charged particals inside the membrane
this produces a positive voltage swing
the excitation spreads leading to propagation of the action potential along the axon
immediately there is a refraction period
potasium channels open causing hyper polarisation
electrical communications: hyperpolarisation
more negatively charged inside than the resting potential
electrical communications: duing refractory period
cells are less sensitive to stimulation than they are normally
electrical communications; return to resting potential
there are pumps that actively use energy to move sodium ions out of the neutron for every two potassium ions it puts in
At rest, again there are rela;vely more sodium ions outside the neuron and more potassium ions inside that neuron
electrical communications: sequence of events of action potential
neuron membrane is disturbed
sodium channel opens and sodium floods in
when voltage reaches -55 the neutron fires sending a wave of electrical impulse along the neutron
sodium channels close and potasium opens reversing depolarisation
potasium channels close
ack to resting potential
electrical communications: propagation is muc faster if …
axon is myelinated
Depolariza$on proceeds down the axon by a number of skips or jumps because ion cannels only open at the nodes of ranvier
electrical communications: action potential and the all o none law
Once it’s launched, further increases in s;mulus intensity have no effect on its magnitude.
interneural communication
at axon terminal the electrical signal causes the release of specialised chemicals these chemical (neurotransmitters) travel across synapse to next neutron
chemical communications: synapse
the unction between two neutrons consisting of the presynaptic membrane
post synaptic membrane
and synaptic cleft between them
chemical communications: neurotransmitters
make communication between two neutrons possible by:
crossing synapse
latching onto receptors on postsynaptic cel
triggering a response in the ell
some neurotransmitters are deactivated shortly after being discharged, this is done by “clean up: enzymes
they are also more commonly reused by a process called synaptic repute
different kinds of neuro transmitters
chemical communications:lock and key model
proposes that:
transmitter molecules will affect the postsynaptic membranes if the molecules shape fits into certain synaptic receptor molecules
chemical communications: posysynaptic transmission
depending on the type of receptor that is activated the attachment of the neurotransmitters either:
excites or inhibits
the generations of an action potential in the postsynaptic cell
chemical communications; excitatory/inhibitory
the resulting chemical changes are graded and can be either excitatory or inhibitory
whether the neutron fires depends on the sum of these effects
chemical communications: neurotransmitters and drugs
can impede or enhance the action of neurotransmitters
Drugs: agonists
enhance efect of a neurotransmitter
can:
increase release of neurotransmitters, amphetamine doe this
block reputake of neurotransmitters this happens with prosaic and cocaine
can mimic specific neurotransmitters by binding to postsynaptic receptors and either activating them or increasing effects of neurotransmitters main effect of nicotine
drugs:antagonist
impede effect of neurotransmitter
can:
block release of neurotransmitters, main effect of AMPT
destroy neurotransmitters in synapse,
mimic a spacific neurotransmitter binding to postsynaptic receptors enough to block any more neurotransmitter binding, main effect of propanelol (beta blocker) and halloo (antipsychotic drug)
amphetamine
agonist increases the release of neurotransmitters in particular: dopamine neophhephrine
cocaine and prosak
agonist
blocks repute of neurotransmitters
nicotene
agonist
mimics spacific neurotransmitters and either:
activates them
or increases neurotransmitters effects
AMPT
antagonist
blocks release of neurotransmitters
propranalol and Hadol
mimic a spacifi neurotransmitter and bind to postsynaptic receptor enough to stop further binding
neurotransmitters: seratonin
usually inhibitory involved in many mechanisms of: sleep arousal aggression mood appetite overproduction causes OCD
: selective seratonin reuptake inhibitors
reduce uptake of the neurotransmitter from the synapse
prosak Zolott and Paxil:
increase serotonin turnover in brain and
find wide use as treatments for depression, obsessive compulsive disorder etc…
neurotransmitters: GABA
gama-amibo butyric acid
most widely distributed inhibitory transmitter in central nervous system
implicated in anxiety disorders and depression
alcohol and synapses
alcholo has multiple effects on neutrons italters: neutron membranes ion channels receptors enzymes
it bind directly to receptors for: acetylcholine seratonin GABA glutamide
alcohol and the GABA receptor
alcohol binds to GABAreceptors and amplifies the hyperpolarization effect of GABA
neutron activity is further diminished
this accounts for some of the sedative affects of alcohol
hyperpolarization
occurs when the strength of an electric field across a cell membrane increases
if the changes in the negative potential do not reach the -50mv action potential they are said to be…
graded potentials
action potentials occur in…
axons
dendrites
cell bodies
adrenal glands secrete hormones that regulate the …
metabollic processes
the key mechanism of the action potential is…
the action of the sodium and potassium channels in the cell membrane
when sodium ions flood into cell this is…
depolarisation
overactivity of serotonin is ascociated with
obsessive compulsive disorder
Sperrys ecperiment
selected participants who were right handed show localisation of the brain and that verbal abilities were located on the left hemisphere
researchers use these kinds of brain damage to investigate the function of different areas of the brain
degenerative disead tumour vascular infectious disease trauma epilepsy
the association cortex is involved in…
many important mental function such as: perception
langage
thought
why researcher might use an EEG
to explore the possibility of abnormal activity within the brain
amphetamine increases the activity of …
Dopamine
Noephephrine
for a neuron to fire theorised must be…
+40 mv compared to the outside
the brain is made up of…
fluid
fat
protein
an inhibitory neurotransmitter causes…
negative chloride ions from the exterior to flow in
positive potasium ions t flow out of the neuron
the neurotransmitter endorphin is the best known…
neuromodulator
synaptic vesicles are…
chambers within the icon terminals where neurotransmitter molecules are stored
example of a neuropsychological test
trail making test used to test memory and planning
james olds 1953 study…
dopamine produced rewarding behaviour in rats
