Neurotransmitters Flashcards
What does depolarisation of the cell lead to?
Depolarization of the
presynaptic terminal opens ion
channels, allowing calcium (Ca2+) into the cell
When Ca2+ is released, what does it trigger?
the Ca2+ triggers the release of neurotransmitter from vesicles by
exocytosis from the presynaptic
neuron into the synaptic cleft.
Once the neurotransmitter is released, what does it bind to?
Neurotransmitters bind to adjacent cell at the
receptor sites attached to ion channels or G
protein-coupled receptors
what happens when the ion channels open?
The channels open allowing the movement of ions
into or out of the postsynaptic cell, which alters its
membrane potential thereby transmitting the signal
from the presynaptic to the postsynaptic cell
what are the two types of receptors that neurotransmitters bind onto once they cross synaptic cleft?
1.) Ionotropic: Ligand-gated ion Channels (LGIC)
They are ion channels
2.) Metabotropic: G-protein coupled receptors
(GPCR) They mediate the opening of ion channels.
describe fast transmission due to Ligand-gated ion channels
Neurotransmitters bind directly to a channel protein
and mediate the flow of ions across the membrane
for a brief time (Fast Neurotransmission).
describe slow transmission due to G-protein coupled receptor
Neurotransmitters bind to G protein-coupled receptor and activate
a second messenger system mediating the opening of ion
channels for a longer period of time (Slow Neurotransmission)
what is post-synaptic potential?
The potential change produced in post-synaptic cell
what are the two types of post-synaptic potential?
1.) Excitatory Post-Synaptic Potential (EPSP): voltage changes
that enhance the likelihood of an action potential forming
2.) Inhibitory Post-Synaptic Potential (IPSP): voltage changes
that reduce the likelihood of an action potential being produced
which type of post-synaptic potential do Na+ and Ca2+ produce?
Na+ and Ca++ influx always produce an Excitatory PSP
(depolarization of the membrane
which type of post-synaptic potential does K+ produce?
K+ efflux always produces an Inhibitory PSP (Hyperpolarisation
of the membrane)
which type of post-synaptic potential does Cl- produce?
Cl- flux (in or out) typically produces an IPSP
Hyperpolarisation of the membrane
give an example of excitatory neurotransmitter
glutamate acetylcholine histamine dopamine adrenaline
give an example of inhibitory neurotransmitter
gamma-aminobutyric acid (GABA)
serotonin
acetylcholine
what is spatial summation?
Spatial summation occurs where multiple neurones can fire impulses to one receiving neurone, where one of those impulses alone will not be sufficient to produce an action potential on the post-synaptic neurone, but if they all fire simultaneously, the impulse will continue along the post-synaptic membrane.
