Lecture 5: Synaptic Transmission and Neurotransmitters
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Questions and Answers

What is the electrical motive force equation for the postsynaptic current at ionotropic receptors?

  • Isyn = gsyn (Vm + ERev)
  • Isyn = gsyn (Vm - ERev) (correct)
  • Isyn = gsyn (Vm / ERev)
  • Isyn = gsyn (Vm * ERev)

    • What is the reversal potential (ERev) for GABAergic synapses?

  • ERev = PCl x ECl
  • ERev = PNa x ENa + PK x EK
  • ERev = 0 mV
  • ERev = -65 mV (correct)

    • For glutamatergic synapses, what is the value of ERev?

  • ERev = 0 mV
  • ERev = PCl x ECl
  • ERev = PNa x ENa + PK x EK; ENa = 60 mV; EK = -90 mV; PNa = 0.6; PK = 0.4 (correct)
  • ERev = -65 mV

    • What determines each ionic current at the receptor channel?

    <p>Iion = gion (Vm - Eion)</p> Signup and view all the answers

    At what membrane potential could a glutamatergic synapse produce an IPSP?

    <p>If Vm is below Erev (for that synapse) I &gt; 0</p> Signup and view all the answers

    What is the value of ENa for glutamatergic synapses?

    <p>+60 mV</p> Signup and view all the answers

    What can change the polarity of an EPSP?

    <p>The membrane potential at the time the EPSP is produced</p> Signup and view all the answers

    Which equation represents the ionic current for each receptor channel?

    <p>$Iion = gion (Vm - Eion)$</p> Signup and view all the answers

    At what membrane potential could a GABAergic synapse produce an EPSP?

    <p>$If Vm &gt; Erev = 0 mV$</p> Signup and view all the answers

    What are postsynaptic currents a sum of at ionotropic receptors?

    <p>$IK$ and $INa$</p> Signup and view all the answers

    Which neurotransmitter is synthetized in the endoplasmic reticulum and packed in the Golgi apparatus before being transported to nerve terminals?

    <p>Dynorphin</p> Signup and view all the answers

    What is the process by which vesicles release their content called?

    <p>Exocytosis</p> Signup and view all the answers

    In the context of neurotransmitter release, what is necessary for synaptic transmission?

    <p>Voltage-dependent Ca2+-channels</p> Signup and view all the answers

    What are the homologs of postsynaptic potentials (PSPs) in neurons?

    <p>Miniature postsynaptic potentials (minis)</p> Signup and view all the answers

    What is the product of two factors that determine the amount of synaptic current (Isyn) at ionotropic receptor channels?

    <p>The permeability of the ionotropic receptor channel (gsyn)</p> Signup and view all the answers

    What is the indivisible unit of synaptic transmission?

    <p>Quantum</p> Signup and view all the answers

    At what membrane potential do excitatory postsynaptic potentials (EPSPs) occur?

    <p>$Vm &lt; Erev$</p> Signup and view all the answers

    What type of flow results in inhibitory postsynaptic potentials (IPSPs)?

    <ul> <li>charges</li> </ul> Signup and view all the answers

    What is the process called where vesicle membrane fuses with presynaptic membrane for release of neurotransmitters into synaptic cleft?

    <p>Exocytosis</p> Signup and view all the answers

    Which neurotransmitter is synthetized by enzymes at nerve terminals and transported to empty vesicles at nerve terminals?

    <p>Adrenaline</p> Signup and view all the answers

    What determines the polarity of an excitatory postsynaptic potential (EPSP)?

    <p>The voltage across the membrane (Vm)</p> Signup and view all the answers

    At what membrane potential do inhibitory postsynaptic potentials (IPSPs) occur?

    <p>$Vm &gt; Erev$</p> Signup and view all the answers

    What is the fundamental difference between electrical and chemical synapses?

    <p>Electrical synapses are faster and bidirectional, while chemical synapses are slower and unidirectional.</p> Signup and view all the answers

    If a postsynaptic potential (PSP) reaches the threshold to generate action potentials, which type of synapse is most likely involved?

    <p>Axo-axonic synapse</p> Signup and view all the answers

    What determines the amplitude of a postsynaptic potential (PSP) in electrical synapses?

    <p>The number of gap-junctions linking the two cells</p> Signup and view all the answers

    Which type of synapse allows many postsynaptic potentials to summate to reach the threshold to generate action potentials?

    <p>Dendro-dendritic synapse</p> Signup and view all the answers

    What is the main feature of an electrical synapse?

    <p>Bidirectional transmission</p> Signup and view all the answers

    In chemical synapses, what is the function of axo-dendritic, axo-somatic, axo-axonic, and dendro-dendritic synapses?

    <p>Indicating the specific locations of transmission</p> Signup and view all the answers

    What is the role of connexons in electrical synapses?

    <p>Forming channels for gap junctions</p> Signup and view all the answers

    What determines the amplitude of a postsynaptic potential (PSP) in chemical synapses?

    <p>The type of neurotransmitter released</p> Signup and view all the answers

    Which type of synapse involves gap junctions and allows for ion flow between connected cells' cytoplasms?

    <p>Electrical synapse</p> Signup and view all the answers

    If a synaptic integration leads to reaching the threshold to generate action potentials, which type of synapse is most likely involved?

    <p>Axo-dendritic synapse</p> Signup and view all the answers

    What type of synapse allows for bidirectional transmission and rapid transmission?

    <p>Electrical synapse</p> Signup and view all the answers

    What determines the amplitude of a postsynaptic potential (PSP) in electrical synapses?

    <p>Coupling efficiency</p> Signup and view all the answers

    What is the main function of connexons in electrical synapses?

    <p>Electrically coupling cells</p> Signup and view all the answers

    What are the four types of axo- synapses in chemical synapses?

    <p>Axo-dendritic, axo-somatic, axo-axonic, dendro-dendritic</p> Signup and view all the answers

    What determines the amplitude of a postsynaptic potential (PSP) in chemical synapses?

    <p>Type and quantity of neurotransmitter released</p> Signup and view all the answers

    What is the role of ion flow at the postsynaptic membrane in chemical synapses?

    <p>Generating postsynaptic potentials (PSPs)</p> Signup and view all the answers

    What is the function of gap junctions in electrical synapses?

    <p>Allowing ion flow between connected cells' cytoplasms</p> Signup and view all the answers

    What determines the polarity of an excitatory postsynaptic potential (EPSP)?

    <p>Influx of cations (e.g., Na+)</p> Signup and view all the answers

    What determines the polarity of an inhibitory postsynaptic potential (IPSP)?

    <p>Efflux of anions (e.g., Cl-)</p> Signup and view all the answers

    What type of synapse involves the formation of gap junctions and allows for the electrical coupling of cells?

    <p>Electrical synapse</p> Signup and view all the answers

    What is the equation for the reversal potential (Erev) for glutamatergic synapses?

    <p>ERev = PNa x ENa + PK x EK</p> Signup and view all the answers

    What is the value of the reversal potential (ERev) for glutamatergic synapses?

    <p>0 mV</p> Signup and view all the answers

    What is the equation for the ionic current through each receptor channel at ionotropic receptors?

    <p>Iion = gion (Vm – Eion)</p> Signup and view all the answers

    What determines the polarity of an excitatory postsynaptic potential (EPSP) at any synapse?

    <p>If Vm &lt; Erev (for that synapse)</p> Signup and view all the answers

    What determines the amplitude of a postsynaptic potential (PSP) in electrical synapses?

    <p>The conductance and the difference between the membrane potential and the reversal potential</p> Signup and view all the answers

    What could cause a glutamatergic synapse to produce an inhibitory postsynaptic potential (IPSP)?

    <p>If Vm &gt; Erev = 0 mV</p> Signup and view all the answers

    At what membrane potential could a GABAergic synapse produce an excitatory postsynaptic potential (EPSP)?

    <p>If Vm &lt; Erev = -65 mV</p> Signup and view all the answers

    What is the role of connexons in electrical synapses?

    <p>They allow for ion flow between connected cells' cytoplasms</p> Signup and view all the answers

    What are the postsynaptic currents a sum of at ionotropic receptors?

    <p>The ionic currents of the receptor channel (e.g., IK and INa)</p> Signup and view all the answers

    What is the main feature of an electrical synapse?

    <p>Direct electrical coupling between cells</p> Signup and view all the answers

    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?

    <p>2.5 mV</p> Signup and view all the answers

    Is the size of a quantum determined at this synapse applicable to all synapses?

    <p>No</p> Signup and view all the answers

    What is the process that activates exocytosis of synaptic vesicles for neurotransmitter release?

    <p>Arrival of an action potential</p> Signup and view all the answers

    What is the primary mechanism for the release of neurotransmitters into the synaptic cleft?

    <p>Exocytosis</p> Signup and view all the answers

    What is the indivisible unit of synaptic transmission?

    <p>Quantum</p> Signup and view all the answers

    How is the amount of synaptic current (Isyn) at ionotropic receptor channels determined?

    <p>By the permeability of the ionotropic receptor channel (gsyn)</p> Signup and view all the answers

    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?

    <p>4 mV</p> Signup and view all the answers

    What is the process by which synaptic vesicles release their content called?

    <p>Exocytosis</p> Signup and view all the answers

    What is the primary mechanism for neurotransmitter release, which is activated by the change in intracellular calcium concentration?

    <p>Exocytosis</p> Signup and view all the answers

    What determines the amplitude of each mini EPSP in the context of the quantal hypothesis?

    <p>Quantum</p> Signup and view all the answers

    What is the process by which vesicle membrane fuses with the presynaptic membrane for the release of neurotransmitters into the synaptic cleft?

    <p>Exocytosis</p> Signup and view all the answers

    What is the primary factor that determines the amount of synaptic current (Isyn) at ionotropic receptor channels?

    <p>Permeability of the ionotropic receptor channel (gsyn)</p> Signup and view all the answers

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