neurons- types Flashcards
how they communicate, synaptic transmission, summation, neurotransmitters, types and structure of neurons
nerve impulses are triggered in the
cell body
where do small waves of positivly charged particles enter the neurone
at the dendrites
if the charge particle entering the dendrite is weakly positive will a nerve impulse occur
no
A neuron only generates a nerve impulse if (2)
there is a change in voltage in the cell body and the change is large/strongly positive so the necessary voltage is created for a nerve impulse to be triggered
where do nerve impulses travel from and to
dendrites to axon terminals
the electrical signals are actually
changes in voltage
how does voltage change
if there are more or fewer charged particles inside the neurone
where are sensory neurons located
near our sensory receptors
sensory neurons send information towards the
cns
sensory neurons receive information from our
sensory receptors
where are the sensory receptors
eyes, skin, tongue, nose and ears
the axon terminals on a motor neuron are positioned next to
next to the muscles
relay neurons can process and transform what type of info
sensory information
do sensory neurons have large dendries to receive sensory information
no
what is the first stage of synaptic transmission
the nerve impulse arrives at the pre synaptic terminal and causes the synaptic vesicles to travel down to the pre synaptic membrane
what is the second stage of synaptic transmission (after the sv travels to psm)
the synaptic vesicle and pre synaptic membrane fuse causing neurotransmitters to be released into the synaptic cleft
what is the third stage of synaptic transmission (after N are released into sc)
the neurotransmitters diffuse across the synaptic cleft towards the post synaptic terminal and then bind to post synaptic receptors
explain the process of synaptic transmission (4)
electrical impulses (action potentials) reach presynaptic terminal
they trigger the release of neurotransmitters from synapse vesicles
neurotransmitters diffuse across synaptic cleft
they bind to receptors on the postsynaptic membrane
inhibition/excitation
neurotransmitters bind to
receptors on the post synaptic membrane
what do the recpetors on the post synaptic membrane usually do?
block the positivley charged ions from entering the dendrite/post synaptic neuron
how do neurotransmitters effect the receptors
they open a gate allowing (small) +charged ions to enter the post synaptic terminal
When positively charged particles flow into the post-synaptic neuron, they cause…
a small positive change in voltage (in the dendrites/post synaptic neuron)
what causes more positively chareged particles to flow into dendrites and what effect does this have on voltage
if there are more neurotransmitters bound to the receptors then more will flow in this will result in a greater change in the voltage
If the change in voltage is big enough, then a …….. i triggered in the cell body
a nerve impulse/action potential
the more neurotransmitters are released by the pre synaptic neuron the more neurotransmitters will…
bind to receptors
The more neurotransmitters are released by the pre-synaptic neuron the bigger the change
in voltage
The more neurotransmitters are released by the pre-synaptic neuron the more likely
a nerve impulse is triggered
The more neurotransmitters are released by the pre-synaptic neuron the more + charged
particles will enter the neuron
what happens to a post synaptic receptor when a neurotransmitter bind to it
it changes shape to allow flow into the post synaptic terminal
The more positively charged particles flow into the post-synaptic terminal the more likely….
it is that a nerve impulse is generated at the cell body
once the neurotransmitter binds to the receptor and +charged particles have flowed into the post synaptic membrane, what happens
the neurotransmitter is released back out into the synaptic cleft
once the neurotransmitters are released back into the synaptic cleft, what would happen if they stayed in the cleft
they would keep binding to the receptors, transferring more +charged particles and creating more impulses
what is the process of reuptake
reuptake proteins on the pre synaptic membrane suck up the free neurotransmitters in the synaptic cleft back into the pre synaptic terminal so that they can be used again
after synaptic transmission what are the 3 ways that the neurotransmitters are cleared from the synaptic cleft
reuptake
diffusion
breakdown
most neurotransmitters can bind to various…..
types of receptors eg serotonin can bind ot 10
SSRI antidepressants inhibit …… in order to prolong
inhibit reuptake in order to prolong the effect of neurotransmitters
the quicker the reuptake of the neurotransmitter the ………
shorter the effects on the postsynaptic neuron
excitatory synaptic connection do what to neural activation in the CNS
increase
Most of the time, only a small amount of neurotransmitter is released into the synapse. This means that…
A small number of positively charged particles flow into the post-synaptic neuron.
There will be a small change in voltage in the post-synaptic neuron.
summation is when successive changes….
Summation is when successive changes in voltage add up in the post-synaptic neuron.
when multiple small changed in voltage add up together
summation occurs when multiple ……… occur in the …….. neuron ……
Summation occurs when multiple nerve impulses occur in the pre-synaptic neuron, in quick succession
OR multiple nerve impulses occur at multiple synapses at the same time.
a process that makes it more likely a nerve impulse will be triggered
the post synaptic neuron may also form
multiple other synapses with other neuron
inhibitory neurotransmitters cause
negatively charged particles to enter the post synaptic neuron (inhibitory postsynaptic potential IPSP) = less likely the neuron will fire an impulse
l
Excitatory neurotransmitters cause
positively charged particles to enter the post-synaptic neuron (excitatory postsynaptic potential EPSP) = increasing the likelihood that the postsyanptic cell will fire
egs of excitatory neurotransmitter
glutamate, noradrenaline
eg of inhibitory neurotransmitter
GABA
do inhibitory synaptic connections increase or decrease neural activity in the cns
decrease
ipsp can do what to epsp if a neuron can receive them both
they can cancel them out but epsp and ipsp can summate, for an impulse so occur there needs to be more excitatory neurons
Both inhibitory and excitatory neurotransmitters will bind to the post-synaptic receptors, allowing for both negatively and positively charged particles to enter the neuron. These opposite charges will summate, cancelling each other out, making a nerve impulse less likely to occur.
whether a nerve impulse occurs depends on the …..
balance of excitatory and inhibitor neurotransmitters binding to the post synaptic receptors
what is the name of the neurotransmitter which is released by neurons controlling our muscles causing muscle movements
acetylcholine
Acetylcholine makes nerve impulses more likely to happen, so it is an
excitatory neurotransmitter
dopamine is released between neurons that help control the brains …..
what type of neurotransmitter is it
response to reward
can be excitatory or inhibitory
serotonin is released between neurons that help control
what type of neurotransmitter is it
mood
can be excitatory or inhibitory
which is the main inhibitory neurotransmitter used in the brain
GABA
what affect will gaba have on neural transmission
it will cause negatively charged particles to enter the posy synaptic neuron causing a negative change in voltage making it less likely than an impulse will be fired
When positively charged particles flow into the neuron, this causes a change in voltage called an
excitatory post synaptic potential
When negatively charged particles flow into the neuron, this causes a change in voltage called an
inhibitory post synaptic potential
what are neurons
cells that make up the nervous system which conduct electrical impulses
dendrites …… signals from …. or sensory ….
dendrites receive signals from other neurons or from sensory receptors
what is the cell body/what happens
it is the control centre of the neuron
what is the axon
it conducts the nerve impulses away from the cell body and towards the other neurons
relay neurons are also called
interneurons
which neurons are multipolar and which are unipolar
motor and relay are multipolar
sensory is unipolar
which neurons have a myleinated axon
sensory and motor
which has a longer axon, motor or relay neuron
motor
what does a unipolar neuron mean
only has one extension from the cell body
what does multipolar neuron mean
many dendrites surround the cell body
information can only travel in one direction at a synapse, explain why neurones can only transmit info in one direction at a synapse (3)
the synaptic vesicles containing the neurotransmitter are only present on/released from presynaptic membrane/at the axon terminal of the synapse of the presyanptic neurone
the receptors for the neurotransmitters are only present on the post synaptic membrane at the synapse
it is the binding of the neurotransmitter to the receptor which enables the signal/info to be passed/transmitted to the next neurone
diffusion of neurotransmitters mean they can only go from high to low conc, so can only travel from the presynaptic to postsynaptic membrane
