Neurophys 2- Action potentials and Synaptic transmission
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Questions and Answers

Which neurotransmitter binds to the ionotropic receptor resulting in ion channel opening for sodium and calcium?

  • GABA
  • Glutamate (correct)
  • Serotonin
  • Dopamine

    • Which neurotransmitter is most important for inhibitory functions in the spinal cord?

  • Glutamate
  • Dopamine
  • Acetylcholine
  • Glycine (correct)

    • Which neurotransmitter is associated with excitatory functions in the autonomic nervous system?

  • Norepinephrine (correct)
  • GABA
  • Dopamine
  • Epinephrine

    • Which neurotransmitter binds to the nicotinic receptor resulting in sodium channel opening?

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

    Which neurotransmitter is the most common excitatory neurotransmitter of the CNS?

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

    Which neurotransmitter is associated with the neuromuscular junction and widely expressed throughout the brain as an excitatory neurotransmitter?

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

    What determines the membrane potential of a cell?

    <p>The relative permeability of the membrane to each ion and the concentration of the ion on either side of the membrane</p> Signup and view all the answers

    Why is the membrane potential of a neuron close to, but not the same, as the equilibrium (Nernst) potential for K+?

    <p>The permeability of the membrane to each ion has to be taken into account, which affects the overall membrane potential</p> Signup and view all the answers

    What can cause channels to open or close?

    <p>Voltage, stretch, intracellular and extracellular messengers</p> Signup and view all the answers

    What is required for the production of an action potential?

    <p>Presence of sodium voltage-gated channels</p> Signup and view all the answers

    Where do action potentials occur?

    <p>The axon, axon hillock, and the synaptic terminal</p> Signup and view all the answers

    What is the threshold membrane potential for the opening of Na+ voltage-gated channels?

    <p>-55 mV</p> Signup and view all the answers

    During the depolarization phase, what drives Na+ into the cell?

    <p>Negative electrical force inside membrane</p> Signup and view all the answers

    What happens during the absolute refractory period of the neuronal action potential?

    <p>When the inactivation gate of Na+ VGC is closed</p> Signup and view all the answers

    What determines the conduction velocity of action potentials along a fiber?

    <p>Size of the axon diameter</p> Signup and view all the answers

    What type of channels are mainly involved in generating graded potentials?

    <p>Ligand-gated or mechanically gated ion channels</p> Signup and view all the answers

    What is the main characteristic of the conduction of graded potentials?

    <p>Decremental; permit communication over short distances, degrade over long distances</p> Signup and view all the answers

    What determines the size of graded potentials?

    <p>Strength of stimulus</p> Signup and view all the answers

    What is the role of EPSPs and IPSPs in the integration of graded potentials at the axon hillock?

    <p>EPSPs depolarize, while IPSPs hyperpolarize the membrane potential, affecting the likelihood of an action potential</p> Signup and view all the answers

    Where do action potentials mainly arise and propagate?

    <p>Arise at trigger zones and propagate along the axon</p> Signup and view all the answers

    What is the main difference between the conduction of graded potentials and action potentials?

    <p>Graded potentials exhibit decremental conduction, while action potentials propagate and permit communication over longer distances</p> Signup and view all the answers

    Which type of axons exhibit saltatory conduction?

    <p>Myelinated axons</p> Signup and view all the answers

    What is the speed of impulse conduction for C fibers?

    <p>0.5-2 m/sec</p> Signup and view all the answers

    What is the role of v-SNAREs and t-SNAREs in vesicle release?

    <p>The regulate release of neurotransmitter into the synapse</p> Signup and view all the answers

    What mediates calcium entry for vesicle release in chemical synapses?

    <p>Voltage-gated calcium channels in the presynaptic terminal</p> Signup and view all the answers

    Both graded potentials and action potentials can summate

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

    Both graded potentials and action potentials have refractory periods

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

    Graded potentials are longer in duration than Action potentials

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

    If graded potentials add up in a staircase fashion over time, they are known to participate in....

    <p>Temporal summation</p> Signup and view all the answers

    The whole point of the action potential is to open ____ voltage gated channels in the presynaptic terminal

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

    Which of the following prevents pre-mature release of the pre-synaptic vesicle?

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

    Syntaxin and SNAP-25 are examples of ______

    Signup and view all the answers

    Which of the following is a v-SNARE?

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

    Synaptotagmin acts on which of the following proteins to release the vesicle?

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

    Acetylcholinesterase is an enzyme that....

    <p>Degrades acetylcholine</p> Signup and view all the answers

    Botox treats migranes, wrinkles and muscle spasticity by impairing......

    <p>t-SNARES and v-SNARES</p> Signup and view all the answers

    Graded potentials, like action potentials, always depolarize a neuron first

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

    Graded potentials arise in:

    <p>Dendrites and cell body</p> Signup and view all the answers

    Study Notes

    Neural Conduction and Chemical Synapse

    • In non-myelinated axons, continuous conduction occurs as action potentials are reproduced along the length of the axon.
    • Myelinated axons exhibit saltatory conduction, where the electrical field "jumps" from one node of Ranvier to the next, allowing for faster impulse transmission.
    • A fibers are the largest, myelinated fibers conducting impulses at 12-130 m/sec, while C fibers are the smallest, non-myelinated fibers conducting impulses at 0.5-2 m/sec.
    • Chemical synapses involve the release of neurotransmitters from the presynaptic neuron, which then bind to receptors on the postsynaptic cell membrane.
    • Neurotransmitter vesicles are synthesized, packaged, and transported down the axon via microtubules to the presynaptic terminal.
    • The basic steps of neurotransmitter release involve the arrival of an action potential, opening of voltage-gated calcium channels, calcium entry, and release of neurotransmitter into the synaptic cleft.
    • Calcium entry for vesicle release is mediated by the opening of voltage-gated calcium channels in the presynaptic terminal, not from intracellular store release.
    • Vesicle release is regulated by v-SNAREs and t-SNAREs, which "zipper" together and disengage upon calcium binding, leading to the release of neurotransmitter into the synapse.
    • The release of neurotransmitter from vesicles is quick, taking 1-5 msec post-action potential.
    • Synaptic transmission is essential for communication between neurons and involves the precise release and binding of neurotransmitters.
    • The speed of impulse conduction varies based on fiber size, myelination, and the type of impulse being conducted.
    • The myelin insulation in myelinated axons allows for faster impulse transmission due to the jumping of the electrical field, compared to non-myelinated axons.

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    Description

    Test your knowledge of neural conduction and chemical synapse with this quiz. Explore topics such as continuous and saltatory conduction, neurotransmitter release, synaptic transmission, and the factors influencing impulse conduction speed.

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