64 Questions
What is the electrical motive force equation for the postsynaptic current at ionotropic receptors?
Isyn = gsyn (Vm - ERev)
What is the reversal potential (ERev) for GABAergic synapses?
ERev = -65 mV
For glutamatergic synapses, what is the value of ERev?
ERev = PNa x ENa + PK x EK; ENa = 60 mV; EK = -90 mV; PNa = 0.6; PK = 0.4
What determines each ionic current at the receptor channel?
Iion = gion (Vm - Eion)
At what membrane potential could a glutamatergic synapse produce an IPSP?
If Vm is below Erev (for that synapse) I > 0
What is the value of ENa for glutamatergic synapses?
+60 mV
What can change the polarity of an EPSP?
The membrane potential at the time the EPSP is produced
Which equation represents the ionic current for each receptor channel?
$Iion = gion (Vm - Eion)$
At what membrane potential could a GABAergic synapse produce an EPSP?
$If Vm > Erev = 0 mV$
What are postsynaptic currents a sum of at ionotropic receptors?
$IK$ and $INa$
Which neurotransmitter is synthetized in the endoplasmic reticulum and packed in the Golgi apparatus before being transported to nerve terminals?
Dynorphin
What is the process by which vesicles release their content called?
Exocytosis
In the context of neurotransmitter release, what is necessary for synaptic transmission?
Voltage-dependent Ca2+-channels
What are the homologs of postsynaptic potentials (PSPs) in neurons?
Miniature postsynaptic potentials (minis)
What is the product of two factors that determine the amount of synaptic current (Isyn) at ionotropic receptor channels?
The permeability of the ionotropic receptor channel (gsyn)
What is the indivisible unit of synaptic transmission?
Quantum
At what membrane potential do excitatory postsynaptic potentials (EPSPs) occur?
$Vm < Erev$
What type of flow results in inhibitory postsynaptic potentials (IPSPs)?
- charges
What is the process called where vesicle membrane fuses with presynaptic membrane for release of neurotransmitters into synaptic cleft?
Exocytosis
Which neurotransmitter is synthetized by enzymes at nerve terminals and transported to empty vesicles at nerve terminals?
Adrenaline
What determines the polarity of an excitatory postsynaptic potential (EPSP)?
The voltage across the membrane (Vm)
At what membrane potential do inhibitory postsynaptic potentials (IPSPs) occur?
$Vm > Erev$
What is the fundamental difference between electrical and chemical synapses?
Electrical synapses are faster and bidirectional, while chemical synapses are slower and unidirectional.
If a postsynaptic potential (PSP) reaches the threshold to generate action potentials, which type of synapse is most likely involved?
Axo-axonic synapse
What determines the amplitude of a postsynaptic potential (PSP) in electrical synapses?
The number of gap-junctions linking the two cells
Which type of synapse allows many postsynaptic potentials to summate to reach the threshold to generate action potentials?
Dendro-dendritic synapse
What is the main feature of an electrical synapse?
Bidirectional transmission
In chemical synapses, what is the function of axo-dendritic, axo-somatic, axo-axonic, and dendro-dendritic synapses?
Indicating the specific locations of transmission
What is the role of connexons in electrical synapses?
Forming channels for gap junctions
What determines the amplitude of a postsynaptic potential (PSP) in chemical synapses?
The type of neurotransmitter released
Which type of synapse involves gap junctions and allows for ion flow between connected cells' cytoplasms?
Electrical synapse
If a synaptic integration leads to reaching the threshold to generate action potentials, which type of synapse is most likely involved?
Axo-dendritic synapse
What type of synapse allows for bidirectional transmission and rapid transmission?
Electrical synapse
What determines the amplitude of a postsynaptic potential (PSP) in electrical synapses?
Coupling efficiency
What is the main function of connexons in electrical synapses?
Electrically coupling cells
What are the four types of axo- synapses in chemical synapses?
Axo-dendritic, axo-somatic, axo-axonic, dendro-dendritic
What determines the amplitude of a postsynaptic potential (PSP) in chemical synapses?
Type and quantity of neurotransmitter released
What is the role of ion flow at the postsynaptic membrane in chemical synapses?
Generating postsynaptic potentials (PSPs)
What is the function of gap junctions in electrical synapses?
Allowing ion flow between connected cells' cytoplasms
What determines the polarity of an excitatory postsynaptic potential (EPSP)?
Influx of cations (e.g., Na+)
What determines the polarity of an inhibitory postsynaptic potential (IPSP)?
Efflux of anions (e.g., Cl-)
What type of synapse involves the formation of gap junctions and allows for the electrical coupling of cells?
Electrical synapse
What is the equation for the reversal potential (Erev) for glutamatergic synapses?
ERev = PNa x ENa + PK x EK
What is the value of the reversal potential (ERev) for glutamatergic synapses?
0 mV
What is the equation for the ionic current through each receptor channel at ionotropic receptors?
Iion = gion (Vm – Eion)
What determines the polarity of an excitatory postsynaptic potential (EPSP) at any synapse?
If Vm < Erev (for that synapse)
What determines the amplitude of a postsynaptic potential (PSP) in electrical synapses?
The conductance and the difference between the membrane potential and the reversal potential
What could cause a glutamatergic synapse to produce an inhibitory postsynaptic potential (IPSP)?
If Vm > Erev = 0 mV
At what membrane potential could a GABAergic synapse produce an excitatory postsynaptic potential (EPSP)?
If Vm < Erev = -65 mV
What is the role of connexons in electrical synapses?
They allow for ion flow between connected cells' cytoplasms
What are the postsynaptic currents a sum of at ionotropic receptors?
The ionic currents of the receptor channel (e.g., IK and INa)
What is the main feature of an electrical synapse?
Direct electrical coupling between cells
What is the size of a quantum at the synapse where 10 spontaneous mini EPSPs recorded are 5 mV, 10 mV, 2.5 mV, 5 mV, 2.5 mV, 2.5 mV, 2.5 mV, 7.5 mV, 5 mV, 2.5 mV?
2.5 mV
Is the size of a quantum determined at this synapse applicable to all synapses?
No
What is the process that activates exocytosis of synaptic vesicles for neurotransmitter release?
Arrival of an action potential
What is the primary mechanism for the release of neurotransmitters into the synaptic cleft?
Exocytosis
What is the indivisible unit of synaptic transmission?
Quantum
How is the amount of synaptic current (Isyn) at ionotropic receptor channels determined?
By the permeability of the ionotropic receptor channel (gsyn)
What is the value of the quantum for a synapse if 10 spontaneous mini EPSPs recorded are 8 mV, 16 mV, 4 mV, 8 mV, 4 mV, 4 mV, 4 mV, 12 mV, 8 mV, 4 mV?
4 mV
What is the process by which synaptic vesicles release their content called?
Exocytosis
What is the primary mechanism for neurotransmitter release, which is activated by the change in intracellular calcium concentration?
Exocytosis
What determines the amplitude of each mini EPSP in the context of the quantal hypothesis?
Quantum
What is the process by which vesicle membrane fuses with the presynaptic membrane for the release of neurotransmitters into the synaptic cleft?
Exocytosis
What is the primary factor that determines the amount of synaptic current (Isyn) at ionotropic receptor channels?
Permeability of the ionotropic receptor channel (gsyn)
This quiz covers the types of synapses, neurotransmitter release at synaptic terminals, and the forces driving ion flow at the postsynaptic membrane. It also includes information on the flow of information at a synapse and the different types of synapses, such as electrical synapse.
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