Chapter 8: Synaptic Transmission & Neural Integration Flashcards by Amy Louise Collins

For cells that communicate by electrical synapses, the message travels between cells via ________.

gap junctions

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Which of the following statements about synapses is FALSE?

Neurotransmitters can move from one cell to another through gap junctions at an electrical synapse.

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Which of the following statements about electrical synapses is FALSE?

All electrical synapses provide for bi-directional communication.

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The chemical synapse is bounded by the ________ neuron, from which neurotransmitters are released across the synaptic cleft, to the ________ neuron, where the receptors for that neurotransmitter are located.

presynaptic : postsynaptic

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What type of synapse occurs between an axon terminal of one neuron and the axon from another neuron?

axoaxonic synapse

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What type of synapse occurs between an axon terminal of one neuron and the cell body of another neuron?

axosomatic synapse

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The neurotransmitter that is released from the presynaptic neuron must diffuse across the ________ to reach the postsynaptic neuron.

synaptic cleft

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What type of ion channels are necessary for the function of the axon and the axon terminal?

voltage-gated

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Synaptic vesicles store ________.

neurotransmitter

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Most neurotransmitters are synthesized in what region of a neuron?

cytosol

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Neurotransmitter release occurs by what mechanism?

exocytosis

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Voltage-gated calcium channels in the axon terminal open in response to which of the following?

arrival of an action potential at the axon terminal

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The influx of calcium into the axon terminal of a chemical synapse is responsible for which of the following?

fusion of vesicles to the membrane and of exocytosis neurotransmitter

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Which of the following is NOT a mechanism whereby neurotransmitters are rapidly removed from the synaptic cleft?

transport back up the axon to be immediately repackaged

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Neurotransmitters can be reused through the process of ________, where neurotransmitters are transported across the presynaptic membrane.

reuptake

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The extent of neurotransmitter binding to receptors on the postsynaptic membrane is determined primarily by which of the following?

the concentration of neurotransmitter

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The synaptic delay is caused by the time required for which step of neurotransmitter release?

calcium entry to trigger exocytosis

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What type of receptor is responsible for the rapid opening of ion channels in response to the interaction between the ligand and receptor?

ionotropic receptor

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The opening of ion channels that is stimulated by the binding of a neurotransmitter to its receptor on a neighboring neuron, and the subsequent movement of ions across that membrane, describes the development of which of the following?

postsynaptic potential

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The rapid change in membrane potential that occurs when a ligand binds to an ionotropic receptor is caused by which of the following?

the presence of one protein that functions as both an ionotropic receptor and an ion
channel

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Synaptic potentials are produced at what type of synapse?

axo-dendritic and axo-somatic synapses only

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At ionotropic receptors, a(n) ________.

neurotransmitter binding to a receptor opens channels that are a part of the same protein
as the receptor

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Presynaptic modulation occurs at what type of synapse?

axo-axonic

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Metabotropic receptor-induced gating of ion channels requires more time to occur because of which of the following?

their gating is linked to a G protein

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What is a change in the postsynaptic potential that brings membrane potential closer to threshold called?

excitatory postsynaptic potential

The most common mechanism for producing a fast EPSP involves which of the following?

opening of channels that permit both sodium and potassium to flow through

What ion directly triggers neurotransmitter release from the presynaptic neuron?

calcium

An example of a slow excitatory postsynaptic potential that involves closure of potassium channels relies on cAMP produced by what enzyme?

adenylate cyclase

The duration of a slow, excitatory postsynaptic potential mediated by cAMP is driven by the extent of time that cAMP remains active before being degraded by what protein?

phosphodiesterase

Fast excitatory responses not only occur quickly, but ________.

they end quickly

The binding of a neurotransmitter to its receptor at an inhibitory synapse can lead to the ________ of ________ channels.

opening : chloride

The binding of a neurotransmitter to its receptor at an inhibitory synapse can lead to the ________ of ________ channels.

opening : potassium

In the absence of active chloride ion transport, opening of chloride channels in a cell that has hyperpolarized will result in which of the following?

net movement of chloride out of the cell

In the presence of active chloride ion transport within a neuron, the opening of chloride channels will result in which of the following?

net movement of chloride into the cell

If the resting membrane potential is equal to chlorideʹs equilibrium potential, in which direction will chloride ions move if chloride channels open while the cell remains at resting membrane potential?

Ions will move equally in both directions.

In the absence of an active chloride transporter in the plasma membrane, chloride acts to ________ membrane potential by resisting any change in membrane potential.

stabilize

The opening of a chloride channel acts to ________ the development of an action potential at the axon hillock.

inhibit

Convergence in neurophysiology refers to which of the following?

the communication of several neurons to one postsynaptic cell

The final integration of postsynaptic potentials that determines whether an action potential is generated occurs within what region of a neuron?

axon hillock

The degree of summation that can occur for inhibitory postsynaptic potentials is limited by what?

the equilibrium potential for the ion creating the hyperpolarization

For ionotropic receptors, their ________ response ________ the likelihood that two pulses from the same neuron will summate.

rapid : decreases

Which of the following would increase the likelihood of an action potential being generated in a postsynaptic cell?

presynaptic excitation at an excitatory synapse

Which of the following statements about inhibitory synapses is FALSE?

In presynaptic inhibition, opening of chloride channels can stabilize the membrane, opposing a depolarizing force.

For the slow receptors, the likelihood of summation is ________ by the ________ of time required for those responses to decay.

increased : long period

As the amplitude of the excitatory postsynaptic potential increases above threshold, the time between each action potential will ________, thereby increasing the ________ of the action potentials.

decrease : frequency

Suprathreshold graded potentials within a neuron can generate ________ action potential(s) at the axon hillock, which allows for the ________ of the magnitude of the stimulus.

multiple : frequency coding

Axoaxonic synapses are responsible for ________ the extent of neurotransmitter released at the synapse.

modulating

Presynaptic modulation of neurotransmitter release involves modifying ________ at the axon terminal.

calcium influx

During presynaptic inhibition, the release of a neurotransmitter from the modulating neuron causes which of the following?

a decrease in neurotransmitter release from the neuron it is modulating

Which of the following best describes presynaptic facilitation?

The modulating neuron enhances neurotransmitter release from the postsynaptic cell.

The synthesis of acetylcholine involves an enzyme called ________, which is present within the cytosol and is responsible for converting ________ into acetylcholine.

choline acetyl transferase : acetyl CoA + choline

Neurons that synthesize and release acetylcholine are called ________.

cholinergic neurons

Once released, acetylcholine is degraded by extracellular enzymes into what product(s)?

acetate + choline

What is transported back into the axon terminal of cholinergic neurons to be resynthesized into active neurotransmitter?

Choline

What type of receptor is both ionotropic and cholinergic?

nicotinic receptors

What type of receptor is both metabotropic and cholinergic?

muscarinic receptors

Which of the following is a neurotransmitter that contains a six-carbon ring with two hydroxyl groups and an amine group?

norepinephrine

Which of the following couplings between neurotransmitter and neurotransmitter class is INCORRECT?

adenosine : amino acid

Which of the following is an ionotropic purinergic receptor that binds ATP?

P2X

Biogenic amines are synthesized in what region of a neuron?

cytosol of the axon terminal

The action of adrenergic receptors identifies them as ________ receptors.

metabotropic

Which of the following is a biogenic amine that is NOT classified as a catecholamine?

serotonin

What two enzymes catalyze the breakdown of catecholamines?

monoamine oxidase and catechol-O-methyltransferase

Epinephrine binds best to which of the following receptor types?

beta2 adrenergic receptors

Fast EPSPs are produced at which of the following types of receptor?

both nicotinic cholinergic and AMPA receptors

In which region of the brain does histamine function as a neurotransmitter?

hypothalamus

________ is an amino acid neurotransmitter at excitatory synapses whereas ________ is an amino acid neurotransmitter at inhibitory synapses.

Aspartate : glycine

Which of the following GABA receptor types is coupled to chloride channels?

GABAA only

IPSPs are produced when GABA binds to what class of receptor?

GABAA only

What is the most common inhibitory neurotransmitter in the central nervous system?

GABA

Neuropeptides are synthesized in what region of a neuron?

in the rough endoplasmic reticulum

Which of the following compounds is NOT a neuropeptide?

epinephrine

Which of the following is a hypothalamic neuropeptide that regulates the sleep -wake cycle?

orexin

Nitric oxide is a ________ that functions as a neurotransmitter.

gas

Which of the following chemicals is NOT a known neurotransmitter?

carbon dioxide

What chemical targets CB1 receptors?

tetrahydrocannabinol

When voltage-dependent calcium channels open, calcium moves out of the cell.

FALSE

Every time an action potential reaches the axon terminal, a quick burst of neurotransmitter is released into the synaptic cleft.

TRUE

Excitatory postsynaptic potentials can occur as either fast or slow responses.

TRUE

In the absence of active transport of chloride, membrane potential will determine the concentration of chloride ions across a neuronʹs plasma membrane.

TRUE

Once initiated, excitatory postsynaptic potentials last for hours, especially if a fast receptor is activated.

FALSE

An action potential is triggered if the membrane potential at the axon hillock is depolarized to threshold.

TRUE

IPSPs can only summate with IPSPs, and EPSPs can only summate with EPSPs.

FALSE

Two or more graded potentials originating from a different synapse on the same neuron at approximately the same time will cause spatial summation.

TRUE

Information on the amplitude of a particular response is coded for by the amplitude of the action potential generated.

FALSE

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).

FALSE

An axoaxonic synapse is unique in its ability to affect only one synapse.

TRUE

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

FALSE

Connexons are a necessary component of electrical synapses.

TRUE

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

TRUE

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.

TRUE

Closing of potassium channels causes a hyperpolarization.

FALSE

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

TRUE

Neural integration occurs at a neuronʹs cell body.

FALSE

Presynaptic modulation occurs at axo-somatic synapses.

FALSE

Adenosine is degraded by nucleotidases.

FALSE

GABA is a biogenic amine.

FALSE

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

TRUE

GABA acts as an autocrine at GABA A receptors.

FALSE

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

FALSE

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

FALSE

substance P

A neuropeptide.

serotonin

Biogenic amine, but not a catecholamine.

aspartate

Amino acid neurotransmitter released at excitatory synapses.

acetylcholine

Most common neurotransmitter in the peripheral nervous system.

glycine

Amino acid neurotransmitter released at inhibitory synapses.

norepinephrine

Catecholamine

What channels are the most abundant type of voltage-gated channel within the axon terminal and are responsible for the release of neurotransmitter?

Voltage-gated calcium channels

The opening of a calcium channel in the axon terminal results in the movement of calcium (into / out of) the cell.

into

The synaptic delay required for responses to be generated within the postsynaptic neuron are primarily caused by ________.

the time required for calcium to induce exocytosis

(Opening / Closing) of a potassium channel results in an excitatory postsynaptic potential.

Closing

If the membrane is depolarized to +10 mV, which cation will move more frequently through a small cation channel?

potassium

If the resting membrane potential is -70 mV, which cation will move more frequently through a small cation channel?

sodium

A neuron actively transports chloride ions out of the cell. Opening of chloride channels in response to a neurotransmitter binding to receptors on this neuron will produce (an IPSP / membrane stabilization) thereby (exciting / inhibiting) the neuron.

IPSP : inhibiting

A neuron has no active transport systems for chloride ions. Opening of chloride channels in response to a neurotransmitter binding to receptors on this neuron will produce (an IPSP / membrane stabilization) thereby (exciting / inhibiting) the neuron.

membrane stabilization : inhibiting

Once the neurotransmitter that has activated a slow receptor has been cleared from the synapse, the change in membrane potential (will immediately dissipate / can last a while before dissipating).

can last a while before dissipating

Temporal summation is less likely to occur when the receptor that has been activated is a (fast / slow) receptor.

fast

How will two bursts of action potentials that are traveling along the same neuron induce a temporal summation?

If the second burst reaches the axon terminal to induce the release of neurotransmitter before the first has decayed, the postsynaptic membrane will not have completely returned to resting membrane potential, thereby increasing the magnitude of the change in membrane potential relative to a single burst.

The higher the frequency of action potentials generated, the (more / less) neurotransmitter released at a synapse.

______ must be actively taken up by cholinergic neurons in order to synthesize neurotransmitter.

Choline

Which adrenergic receptor(s) has the greatest affinity for norepinephrine?

alpha and beta1

Name the type of receptor that is present on the axon terminal and that responds to the release of neurotransmitter from that axon terminal.

autoreceptors

What two enzymes degrade catecholamines?

monoamine oxidase and catechol-O-methyltransferase

What is the active ingredient of cannabis?

tetrahydrocannabinol