Question 1

Most communication between neurons in the central nervous system is one -to -one, that is, one presynaptic neuron communicates to just one postsynaptic neuron.

Accepted Answer

Most communication between neurons in the central nervous system is not one-to-one; a single presynaptic neuron can communicate with multiple postsynaptic neurons, spreading its signal across a network of cells. This allows for complex processing and integration of information.

Question 2

If the equilibrium potential of a cation is -40 mV, then opening of channels for this cation will result in excitation of the neuron.

Accepted Answer

Opening of channels for a cation with an equilibrium potential of -40 mV will result in an influx of positive ions, depolarizing the neuron and leading to excitation.

Question 3

Postsynaptic potentials, generated by neurotransmitter binding to receptors on the postsynaptic membrane can be excitatory or inhibitory. Describe inhibitory postsynaptic potentials and how chloride channels can be inhibitory without producing an IPSP.

Accepted Answer

The answer of Postsynaptic potentials, generated by neurotransmitter binding to...

Question 4

Neural integration occurs at a neuron's cell body.

Accepted Answer

The answer of Neural integration occurs at a neuron's cell...

Question 5

Information travels through the nervous system along the axons as action potentials. These action potentials must be transmitted across the synaptic cleft. Describe the process whereby an action potential that has entered the axon terminal is able to induce a change in membrane potential in the postsynaptic membrane, following neurotransmitter binding to a metabotropic receptor.

Accepted Answer

The answer of Information travels through the nervous system along...

Question 6

Adenosine is degraded by nucleotidases.

Accepted Answer

Adenosine is degraded by adenosine deaminase, not nucleotidases. Nucleotidases are involved in the breakdown of nucleotides, not nucleosides like adenosine.

Question 7

Slow postsynaptic potentials can be caused by the opening or closing of ion channels, whereas fast postsynaptic potentials only involve the opening of ion channels.

Accepted Answer

Slow postsynaptic potentials involve both the opening and closing of ion channels and can also be mediated by G-protein coupled receptors, leading to a variety of effects and a slower onset. Fast postsynaptic potentials, on the other hand, are typically mediated by the direct opening of ion channels, such as those for sodium or potassium, resulting in a rapid change in membrane potential.

Question 8

Connexons are a necessary component of electrical synapses.

Accepted Answer

Connexons form the channels that bridge the gap between neurons at electrical synapses, allowing ions and small molecules to pass directly from one neuron to another, facilitating rapid communication.

Question 9

Closing of potassium channels causes a hyperpolarization.

Accepted Answer

Closing of potassium channels prevents potassium ions from leaving the cell, which would otherwise lead to a depolarization or maintain the resting membrane potential, not hyperpolarization. Hyperpolarization is typically caused by the opening of potassium channels, allowing more potassium to leave the cell, making the inside more negative.

Question 10

EPSPs are at least 10 mV in magnitude at the point of synaptic communication.

Accepted Answer

EPSPs (Excitatory Postsynaptic Potentials) are typically smaller in magnitude, often around 0.5 to 2 mV at the point of synaptic communication, not as large as 10 mV.

Question 11

Presynaptic modulation involves a neurotransmitter from the axon terminal of one neuron affecting the membrane potential of an axon terminal from another neuron on which the first has synapsed (axoaxonic synapse).

Accepted Answer

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Question 12

Postsynaptic potentials generated by neurotransmitter binding to receptors on the postsynaptic membrane can be excitatory or inhibitory. Describe excitatory postsynaptic potentials and their temporal characteristics.

Accepted Answer

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Question 13

When one neuron has several axon collaterals that communicate with several other neurons, it is called divergence.

Accepted Answer

Divergence refers to the process where one neuron communicates with several other neurons through its axon collaterals, spreading its signal to multiple target neurons.

Question 14

An axoaxonic synapse is unique in its ability to affect neurotransmitter release, but not the action potential.

Accepted Answer

An axoaxonic synapse influences the amount of neurotransmitter released by the presynaptic neuron onto a postsynaptic neuron, but it does not directly affect the generation or propagation of action potentials in the presynaptic neuron.

Question 15

Once an action potential reaches the axon terminal, that depolarization stimulates the release of neurotransmitters that can be modulated by other neurons that synapse with the axon terminal. Describe how neurotransmitters are released from the axon terminal and how that response is altered by axoaxonic synapses.

Accepted Answer

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Question 16

The similarity in structure between glutamate and GABA are indicative of the similarity in their function.

Accepted Answer

Glutamate primarily acts as an excitatory neurotransmitter in the brain, while GABA functions as an inhibitory neurotransmitter, indicating their functions are largely opposite despite structural similarities.

Question 17

Most neurotransmitters are synthesized in the cytosol and actively transported into synaptic vesicles.

Accepted Answer

Neurotransmitters are typically synthesized in the neuron's cytosol and then actively transported into synaptic vesicles by vesicular transporters, where they are stored until released into the synaptic cleft in response to an action potential.

Question 18

GABA is a biogenic amine.

Accepted Answer

GABA (gamma-aminobutyric acid) is an amino acid that functions as a neurotransmitter in the brain, not a biogenic amine.

Question 19

Presynaptic modulation occurs at axosomatic synapses.

Accepted Answer

Presynaptic modulation typically occurs at axoaxonic synapses, where one neuron's axon connects to another neuron's axon, influencing the release of neurotransmitters. Axosomatic synapses, where an axon connects to a neuron's soma (body), are not primarily associated with presynaptic modulation.

Question 20

GABA acts as an autocrine at GABA_Breceptors.

Accepted Answer

GABA can act as an autocrine signaling molecule by binding to GABA_B receptors on the same cell that released it, modulating its own release and activity.

Quiz 8: Synaptic Transmission and Neural Integration