synaptic transmission Flashcards
are chemical or electrical synapses more common in the CNS?
chemical synapses , but electrical synapses are present esp in regulation of the synchrony of breathing
________connects glial cells
gap junctions
which neurotransmitters are Ca2+ dependent?
chemical neurotransmitters
What happens when Chemical synapse channels open ?
Ca 2+ moves down then gradient inward and a t snare and v snare fusion event occurs ( promoting exocytosis) of the Neurotransmitter
Calcium entry through presynaptic voltage gated calcium channels causes?
neurotransmitter release
calcium entry is ____(speed)_______and calcium clearance is ___________(speed)_______
entry is fas because it involves voltage and ligand gated channels but clearance is slower because it involves exchangers and transporters
what is synaptic facilitation?
when there is lots of Ca2+ from the first action potential and by the time the second action potential occurs there Ca2+ builds up and allows more neurotransmitter release in response. This occurs in the PRESYNAPTIC Membrane
It is not the same as temporal summation in the POSTSYNAPTIC membrane
where are small neurotransmitters synthesized?
the presynaptic terminal
where are neuropeptides synthesized?
the cell body
when there is low frequency stimulation what type of neurotransmitter is released?
preferentially small monocle neurotransmitters are released because there will be a localized increase in Ca2+
when there is high frequency stimulation what type of neurotransmitter is released?
both types: small molecule and neuropeptide because there is a more diffuse increase in Ca2+
which neurotransmitters are harder to get rid of?
neuropeptides
what does it mean that neurotransmitter release is quantal?
with each neurotransmitter release there is an exponential increase in miniature end plate potentials
Gaba A receptors cause influx of ______in the cell?
Cl-
ESPS ( excitatory postsynaptic ___________the probability that an action potential will be triggered.
increase
what is the normal intraneuronal potential?
-65 milivolts
why do we need 100s of ESPS and ISPS ?
because dendrites are leaky and thin so when a neuron is excited you need lots of theses because if too few there will not be an effect.
***the CNS especially needs a lot of ESPS/ISPS
Temporal and Spatial summation determine the probability that ________?
an action potential will be generated
the PSPs produced by each synapse sum together in space and time to determine the response of the ________ _________
postsynaptic neuron
what type of neurotransmitter receptors does glutamate bind to?
both ionotropic and metabotropic
what happens to the time the channel is open when barbiturates like pentobarbital is present?
it increase the channel open time
what do GABA A receptors mediate?
fast IPSP via the flow of Cl - ions down their electrochemical gradient
what type of channel is a GABA receptor channel?
ligand gated
Why are GABA B receptor channels slower in transducing signals than GABA A ?
because GABA B is g-protein linked rather than ligand gated.
metabotropic receptors are slower at transducing signal b/c?
they are g-protein linked rather than ligand gated.
When does AMPA fire?
always because it is ligand gated
When does NMDA fire?
when there is enough stimulus ( i.e. high enough membrane potential: voltage @ - 40 mv )is high enough to remove the Mg2+ block
therefore it doesn’t fire at resting potential - 80 mv, because it is both ligand gated and voltage dependent
