Foundations of neuroscience week 6 Flashcards
Neurons have several maim parts common to all human cells
Soma
Nucleus
Membrane
Dendritic are covered in
Dendritic spines
Dendritic spines
Small protruding structures found on thr surface of dendritic in neurons
Acts
Acts as a receiving point for chemical release by other neurons
Neuronal azons are coated in
Myelin
Myelin sheath
Is a insulting material derived fringe specialized giap cells
Acts
To speed up action potentials (the electrical signals of neurons)
There are some (fewer) __ in the brain
Unmyelinated neurons
Schwann cells
Are glial cells that produce myelin but can only myelinate a single axon; they are located in the peripheral nervous system
Oligodendrocytes
Are glial cells that produce mylin, and can myelintlate mutiple; they are located in the central nervous system
Myelin is produced by
Glial cells
In the vrain myelin is produced by
Oligodendrocytes
Nodes of ranvier
Gaps in myelin
what happens when myelin is damaged
neuron signaling slows down
this is the cause of
multiple sclerosis
multipe sclerosis
a chronic disease of the central nervous system (thought to be an autoimmune disease) caused by the loss of myelin around neuronal axons
membrane
a lipid bilayer surrounding neurons, controlling ion flow, signal reception and cell communication for neuron function
in neurons the membrane plays a crucial role in
regulating electrical activity of the cell
embedded in the membrane are
proteins
such as
ion channels
resting potential
is the baseline electrical charge across a neurons membrane when at rest
the extracellular fluid
the difference in charge between inside the cell and outside the cell
this electrical charge is about
-70 millivolts
this charge is maintained by two key features
ion channels
sodium potassium pump
ion channels
specialized proteins in the cell membrane that selectively allow specific ions like sodium, potassium, calcium and chloride to pass through
sodium potassium pump
a cellular protein that actively transports sodium ions out of cells and potassium ions into cells, maintaining ion balance essential for cell function
these two mechanisms maintain the __ negative charge inside of the neuron
-70m charge
this charge is relative to the
extracellular fluid (cytoplasm)
The resting potential is required for
action potentials to occur
what is required for action potentials to occur
the resting potential
action potential
is a very brief shift in a neurons electrical charge that travels along an axon
during an action potential there is
there is a sudden reversal in the electrical charge of the cell
__ from the extracellular fluid rush into the cell
Ions
the electrical charge from inside the neuron rapidly, reverses from about
-70mv to about +30mv
this reversal is called
depolarization
action potential typically beginds near
the soma of the neuron
it then
propagates down the length of the axon rapidly
this is aided by
myelin
it increases the speed so
this charge can propagate down the length of the axon
this allows
individual neurons to send information over quite long distances ( the length of their axon
when an action potential begins __ executed
full executed
what happens when simulation of a neuron reaches a certain threshold
it triggers a full- strength action potential while sub-threshold stimuli do not produce any response
what is the all-or-none law
neurons either fire an action potential or they don’t
since action neurons only have on and off states intensity of stimuli
must be codded
action potentials can occur at very
high rates
some neurons can fire action potentials
tens or hundreds of times per second
faster firing =
more intense
after the reversal of the neurons charge there is
a brief period before it can reset back to normal resting potential
during this period its is not possible for
the neurons to fire again
absolute refractory period
the minimum length of time after an action potential during which another action potential cannot begin
neuronal axons out to __ with other neurons
communicate
those axons often reach the __
dendrites of another neuron
we call the first neuron
pre-synaptic
we call the second neuron post-synaptic
the neuron receiving a signal
pre-synaptic
the neuron sending a signal
post-synaptic
the neuron receiving a signal
when neurons form a connection with other neurons
synapse
synapse
is a specialized junction or connection between two neurons that allows for the tranelectrochemical signals
it is where __ and __ occur in the nervous system
communication and signal transmission
it enables
neurons to transmit information to other cells
most neurons dont __ each other
touch
synaptic gap
the small space between the axon terminal of a pre-synaptic neuron and post-synaptic neuron
what happens here
chemicals are released form the pre-synaptic neuron onto the post-synaptic heron
allows for
neurons to communicate chemically
the primary mechanism by which neurons communicate is
through chemical transmission
neurons send __ across the synaptic gap
molecules
neurotransmitters
chemical messengers that facilitate communication between neurons
there are 8 key stages in neurotransmission
1) synthesis
2) transportation and storage
3) release
4) binding
5) deactivation
6) autoreceptor activation
7) reuptake
8) degradation
in order for neurotransmitters to be released, they
they must first be produced
neurotransmitters are produced within
neurons from precursor molecules
synthesis
the process by which the body produces neurotransmiters which are essential for nerve cell communication
where are neurotransmitters stored
stored in containers called vesicles
synaptic vesicle
a small structure within a neuron that stores neurotransmitters, releasing them into the synaptic cleft to facilitate communication with other neurons
neurotransmitters produced in the cell body of a neuron must then be
transported to the axon where they will be released
the release of neurotransmitters is triggered by action
action potentials
action potentials travel
down the axons length
when they reach the end there are
axon terminals
when the action potential reaches an axon terminal it causes
neurotransmitters to be release into the synaptic gap
exocytosis
the process of moving molecules form within a cell to the exterior of the cell
neurotransmitters travel across the synapse and bind to the post-synaptic cell causing
some biological change/activity in the post-synaptic cell
receptors
proteins on the surface of neurons that neurotransmitters bind to, allowing for the transmisson of signals between the nerve cells
what happens when a reurotransmitter reaches a post- synaptic neuron
neurotransmitters bind to a receptor which can excite or inhibit the neuron that they bound to
this makes it
either more or less likely to fire an action potential
excitation
occurs when neurotransmitters increase a neurons potential for firing an action potential
inhibitition
happens when neurotransmitters decrease a neurons potential for firing an action potential
after binding the effects of neurotransmitters must be
neutralized
this occurs when
the neurotransmiteer unbinds from these receptors
prevents
neurotransmiters from having neveer0-ending effects in the synapse
deactivation
the process of terminating or reducing the effect of a neurotransmitter in the synaptic cleft to ensure controlled neural signaling
what happens to neurotransmitters left unbound in the synaptic gap
there are three main prcoesses by whihc neurotransmitters are elmintaed form the synapse
1) diffusion
2) reuptake
3) degradation
diffusion
neurotransmitters simply drift out of the synaptic cleft where they are absorbed by glial cells
some neurotransmitters also bind to the neuron that
released them
autoreceptors
receptors on the releasing (pre-synaptic) neuron
reuptake
the reabsorption of a neurotransmitter by the presynaptic neuron after it has been released into the synaptic cleft
some neurotransmitters may also be removed form the synaptic gap by
being reabsorbed by the pre-synaptic neuron
enzymes can facilitate deactivation by
breaking apart neurotransmitter molecules
enzymatic degradation
when enzymes in the synaptic cleft break down neurotransmitter molecules into inactive byproducts terminating their signaling effect
neurons produces many
different types of neurotransmitters
some neurotrasnmitters are only produced by
specific small groups or neuorns in the brain
neurotransmitters share four common properties
1) they are synthesized in the neuron
2) they are stored in the synaptic terminals
3) they are released when a neuron has an action potential
4) they are deactivated/removed form the synapse after neurotransmisson
the primary inhibitory neurotransmitter in the brain
GABA
when it binds to GABA receptors it
neuronal excitation when it binds to GABA receptors
the primary excitatory neurotransmitter in the brain
glutamate
when it binds to glutamate receptors it
increases neuronal excitation when it binds to glutamate receptors
serve as the
the most abundant-common neurotransmitter in the brain that serve these two functions
both are narrowly or widely distributed throughout the brain
widely
many anti-anxiety drugs work by
targeting GABA
two examples
Benzodiazepines valium/diazepam
works by
suppressing CNS activity
this is because
GABA is a primarily inhibitory neurotransmitter ( reduces GABA is a primarily inhibitory neurotransmisson/arousal)
monoamines
are a group of GABA is a primarily inhibitory neurotransmitter
say 3 examples
dopamine, noradrenaline (norepinephrine) and serotonin
dopamine is involved in
moment and reward (pleasure)
give two examples when its released
eating, sex, etc.
noradrenaline
mobilize the brain and body for action, increases attention and vigilance; released during stress/fear (fight-or flight response)
serotionin
involved in many complex behaviours/cognitions
gives three examples of cognitions its involved in
sleep, mood, memory
dopamine is secreted
small group of neurons in the brains
when these become damages it leads to
parkison’s disease
parkinsons disease
a progressive neurological disorder characterized by symptoms like tremors, slowness of movement, muscle stiffness and balance problems
many antidepressant drugs target
serotonin
give an example
Selective serotonin reuptake inhibitors
SSIs function by
blocking serotonin reuptake which leaves more serotonin in the synaptic gap
Norepineprhine is synthesized form
dopamine
acts as
a neurotransmitter and as a hormone
Drigs fro attention deficit disroders typically traget
NE
Give an example
Amphetamines
Amphetamines ___ Ne levels in the ___
increase brain
Acetylcholine is the only
transmitter between motor neurons and voluntary muscles
required for
all movement
primary neurotransmitter of the
parasympathetic nervous system
some posions block acetylcholine give two examples
atropa belladonna (deadly nightshade)
