Deck 13: Synapses

Question 1

The ability to change the functional property of the synapse is the key to

A) the neuron.
B) the receptor-transmitter complex.
C) learning and memory.
D) the axonal membrane.

Answer 1

C

Question 2

A specialized site of contact of one neuron with another neuron (or effector) is known as a

A) neuron.
B) receptor-neurotransmitter complex.
C) membrane.
D) synapse.

Answer 2

D

Question 3

Which of the following transmits information the fastest?

A) Ionotropic EPSP
B) Metabotropic IPSP
C) Electrical synapse
D) Fast EPSP

Answer 3

C

Question 4

In an electrical synapse, the main structure responsible for transmission of an impulse from one cell to the next is

A) any generic activating neurotransmitter.
B) acetylcholine.
C) the gap junction.
D) the cell membrane.

Question 5

Which structure is associated with signal transmission in an electrical synapse?

A) Postsynaptic densities
B) Synaptic vesicles
C) Neurotransmitters
D) Connexons

Question 6

Which protein is most uniquely associated with a metabotropic receptor?

A) Neurotransmitter
B) Second messenger
C) Ligand-gated receptor
D) Voltage-gated receptor

Question 7

In chemical synapses, neurotransmitters are released by

A) facilitated diffusion.
B) calcium-dependent exocytosis.
C) active transport.
D) vesicular cycling.

Question 8

Which of the following is a disadvantage of a chemical synapse (as compared to an electrical synapse)?

A) amplifies the synaptic response
B) can be either excitatory or inhibitory
C) relatively slow
D) much more modifiable

Question 9

Refer to the figure shown.
What is occurring at point 4a?

A) Depolarization
B) Hyperpolarization
C) An action potential
D) Muscle contraction

Question 10

Refer to the figure shown.
What is occurring at point 5?

A) Signaling cascade
B) Release of neurotransmitter into the synaptic cleft
C) Reuptake
D) Exocytosis

Question 11

Which statement regarding neurotransmitters is true?

A) Small-molecule neurotransmitters are synthesized mainly in the nucleus.
B) Small-molecule neurotransmitters are contained in large dense-cored vesicles.
C) Neuropeptides are synthesized at the axon terminal.
D) The inactivation of small molecule neurotransmitters can occur via reuptake or via enzymes.

Question 12

Once acetylcholine is released into the synapse it

A) is actively pumped back into the presynaptic neuron.
B) crosses the postsynaptic membrane and then is broken down inside that cell.
C) is inactivated by calcium.
D) is broken down by acetylcholinesterase.

Question 13

Which neurotransmitter elicits responses of both ionotropic and metabotropic receptors?

A) Acetylcholine
B) Dopamine
C) Glutamate
D) Both acetylcholine and glutamate

Question 14

The enzyme tryptophan hydroxylase synthesizes what neurotransmitter?

A) Acetylcholine
B) Serotonin
C) Dopamine
D) Norepinephrine

Question 15

The major excitatory neuromuscular junction neurotransmitter in a moth is

A) acetylcholine.
B) glutamate.
C) glycine.
D) GABA.

Question 16

What is a miniature EPSP (mEPSP)?

A) The movement of Na⁺ across the postsynaptic membrane
B) The diffusion of a neurotransmitter across the synapse
C) A depolarization caused by the release of a neurotransmitter from several synaptic vesicles
D) The postsynaptic response to the release of the contents of one synaptic vesicle

Question 17

A quantum is

A) a count of the number of acetylcholine molecules in a vesicle.
B) a measure of the total amount of acetylcholine released into the synapse.
C) a measure of the stored acetylcholine in the presynaptic terminal.
D) the number of vesicles in the synapse.

Question 18

How were extracellular ion concentrations manipulated in the experiments supporting the theory of quantal release of neurotransmitters?

A) Ca²⁺ was increased in the extracellular fluid so that action potentials would release many vesicles.
B) Ca²⁺ was absent in the extracellular fluid so that action potentials would release no vesicles.
C) Mg²⁺ replaced Ca²⁺ in the extracellular fluid so that action potentials would release few vesicles.
D) Mg²⁺ replaced Ca²⁺ in the extracellular fluid so that action potentials would release many vesicles.

Question 19

How do we account for the two hypotheses of vesicular fusion and retrieval?

A) There is more experimental support for the classical pathway of neurotransmitter release.
B) There was very little support for the classical pathway of neurotransmitter release, therefore the kiss-and-run pathway is currently the favored pathway.
C) Both pathways are portions of a larger pathway and therefore there should be one hypothesis.
D) The kiss-and-run pathway is likely used at lower rates of neurotransmitter release while the classical pathway predominates at higher rates of neurotransmitter release.

Question 20

Which statement best describes the fusion process in exocytotic release of neurotransmitter?

A) v-SNARE proteins attach to t-SNARE proteins.
B) Synapsin detaches the vesicle from the cytoskeleton.
C) Dynamin interacts with clathrin.
D) Calcium interacts with synaptotagmin.

Question 21

Which statement regarding the mechanism of vesicular docking and release is false?

A) Targeted vesicles move to active zones where they attach reversibly.
B) Docking is mediated by the formation of a SNARE complex.
C) The v-SNAREs and t-SNARES interact to hold the vesicle at the release site.
D) Fusion is triggered by the binding of Ca²⁺ to syntaxin.

Question 22

Which ion must enter the presynaptic terminal in order to mediate the release of the neurotransmitter?

A) Ca2⁺
B) Cl^-
C) Na⁺
D) K⁺

Question 23

Ultimately, it is the _______ that determines whether the postsynaptic membrane produces an inhibitory postsynaptic potential (IPSP) or an excitatory postsynaptic potential (EPSP).

A) frequency of action potentials
B) movement of ions
C) neurotransmitter
D) receptor's affinity for the neurotransmitter

Question 24

Two sets of axons carry stimuli near the axonal hillock. One set produces an IPSP and the other set produces an EPSP. If both sets produce action potentials at the same time, what is the likely effect at the axonal hillock?

A) There will be a hyperpolarization.
B) There will be a depolarization.
C) An action potential will be produced.
D) The potentials created will cancel each other out.

Question 25

Refer to the figure shown.
Where is depolarizing temporal summation occurring?

A) I
B) II
C) III
D) IV

Question 26

Refer to the figure shown.
Where is hyperpolarizing spatial summation occurring?

A) I
B) II
C) III
D) IV

Question 27

The _______ is the flow of ions through all the channels that open in response to release of a neurotransmitter.

A) postsynaptic potential
B) synaptic current
C) action potential
D) voltage

Question 28

During an inhibitory postsynaptic potential, the postsynaptic membrane

A) increases in permeability to K⁺.
B) increases in permeability to Na⁺.
C) decreases in permeability to Cl^-.
D) increases in permeability to Ca²⁺.

Question 29

Which statement regarding postsynaptic potentials is true?

A) In a neuromuscular synapse, the main neurotransmitter is glutamate.
B) In a CNS neural synapse, serotonin produces an IPSP.
C) In a CNS neural synapse, K⁺ is the main ion producing the EPSP.
D) In a neuromuscular synapse, Na⁺ is the main ion producing the EPSP.

Question 30

Fast IPSPs result mainly from a(n) _______ in permeability to _______.

A) decrease; Na⁺
B) increase; Cl^-
C) increase; K⁺
D) increase; Na⁺

Question 31

How does the acetylcholine receptor respond to prolonged exposure to acetylcholine?

A) The receptor will flicker, and the rate of flickering will increase.
B) Acetylcholine will no longer be able to bind to the receptor.
C) Acetylcholine will remain bound to the receptor, and the channel will remain open indefinitely.
D) Acetylcholine will remain bound to the receptor, but the channel will close.

Question 32

Which statement regarding the ligand-gated channel at the vertebrate neuromuscular junction is false?

A) It binds acetylcholine.
B) K⁺ travels through this channel when it is open.
C) Two acetylcholine molecules need to bind to the intracellular side of the receptor.
D) When the channel opens, ions depolarize the membrane.

Question 33

Refer to the figure shown.
What technique is being used to collect the data presented?

A) Voltage clamp
B) Ion flux
C) Stimulation
D) Patch clamp

Question 34

Refer to the figure shown.
What is the principal ion that is moving?

A) Na⁺
B) K⁺
C) Ca²⁺
D) Cl^-

Question 35

Refer to the figure shown.
Which statement best describes what is occurring in the bottom panel?

A) More electrical stimulation is occurring on the voltage-gated channels; therefore, they open with more frequency.
B) The increased concentration of acetylcholine eventually overwhelms the receptors, and the bottom panel represents what will happen just before they remain open permanently.
C) Because the channels are staying open longer due to increased acetylcholine concentration, K⁺ begins to move in significant quantities.
D) In this section of membrane, there are two acetylcholine channels that, in the presence of increasing neurotransmitter concentration, have an increasing probability of being open at the same time.

Question 36

Which statement best reflects the evolutionary history of the ligand-gated channel?

A) The sequence homology of the ligand-gated receptors is similar to that of voltage-gated receptors.
B) Ligand-gated channels have had a minimum of three independent appearances in evolutionary history.
C) Ligand-gated channels in the neuromuscular junction are evolutionarily distinct from ligand-gated channels in the brain.
D) Most kinds of ligand-gated channels appear to have evolved from a common ancestor.

Question 37

Why are the synaptic effects of ionotropic receptors faster than those of metabotropic receptors?

A) ionotropic receptors open by voltage changes
B) ionotropic receptors are G proteins
C) ionotropic receptors use a second messenger system
D) ionotropic receptors function as ligand-gated channels

Question 38

How does the G protein activate adenylyl cyclase?

A) The G protein mediates the release of cAMP-dependent protein kinase, which activates adenylyl cyclase.
B) The G protein activates various second messengers, which all activate pathways that activate adenylyl cyclase.
C) The α subunit of the G protein, with GTP, diffuses laterally in the membrane and binds to and activates adenylyl cyclase.
D) The G protein causes a depolarization, which activates adenylyl cyclase.

Question 39

Which response is not directly mediated by a G protein?

A) Activating cAMP-dependent protein kinase
B) Opening of a K⁺ channel
C) Activating adenylyl cyclase
D) Activating phospholipase C

Question 40

Which second messenger acts directly to mediate the release of Ca²⁺ from the endoplasmic reticulum?

A) Diacylglycerol (DAG)
B) Inositol triphosphate (IP₃)
C) Calmodulin
D) Phospholipase C

Question 41

Antidepressants, such as Prozac, work by

A) upregulating the production of serotonin.
B) stimulating serotonin receptors.
C) inhibiting the reuptake of serotonin.
D) increasing the number of serotonin receptors.

Question 42

Refer to the figure shown.
The primary site of behavioral plasticity is at the _______ synapse.

A) head-to-motor neuron
B) sensory-to-motor neuron
C) skin-to-sensory neuron
D) motor neuron-to-gill

Question 43

Refer to the figure shown.
Which mechanism explains Panel 1?

A) At the synapse, the neurotransmitter changes function.
B) The amount of neurotransmitter per presynaptic impulse changes.
C) Receptor density on the postsynaptic membrane changes.
D) The frequency of action potentials increases.

Question 44

Refer to the figure shown.
What are the best titles for Panel 1 and Panel 2?

A) Panel 1 = Motor-neuron EPSP; Panel 2 = Gill withdrawal
B) Panel 1 = Skin PSP; Panel 2 = Gill contraction
C) Panel 1 = Synapse EPSP; Panel 2 = Head EPSP
D) Panel 1 = Synapse EPSP; Panel 2 = Gill contraction

Question 45

Which statement best describes the mechanism of sensitization?

A) Protein kinase dephosphorylates Ca²⁺ channels and decreases the Ca²⁺ current that normally terminates the action potential, which leads to a decrease in Ca²⁺ influx.
B) Protein kinase phosphorylates K⁺ channels and decreases the K⁺ current that normally terminates the action potential, which leads to an increase in Ca²⁺ influx.
C) Protein kinase dephosphorylates K⁺ channels and increases the K⁺ current that normally terminates the action potential, which leads to an increase in Ca²⁺ influx.
D) Protein kinase phosphorylates Na⁺ channels and decreases the Na⁺ current that normally activates the action potential, which leads to a decrease in Ca²⁺ influx.

Question 46

Which occurrence in the synapse is not likely to be involved in the formation of long-term memories?

A) Increase in AMPA receptors in the postsynaptic membrane
B) NMDA receptors mediate increases in intracellular Ca²⁺
C) Long-lasting neurotransmitter release
D) Lengthening of dendritic spines
E) Growth of new dendritic spines

Question 47

Which statement best describes long-term potentiation?

A) Increased synaptic response occurs with increased numbers of AMPA receptors.
B) Increased synaptic response occurs with increased numbers of NMDA receptors.
C) A massive amount of glutamate releases Mg²⁺ from the NMDA receptor.
D) A massive amount of glutamate releases Mg²⁺ from the AMPA receptor.

Question 48

Which statement best describes of the mechanistic uniqueness of the Doogie mouse strain?

A) They have longer-opening NMDA receptors compared to standard lab mice.
B) They produce more neurotransmitters than standard lab mice.
C) They produce more action potentials per second than standard lab mice.
D) They have a better long-term memory than standard lab mice.

Question 49

Which of the following would not be considered synaptic plasticity?

A) Altering the amount of calcium entering the cell at the presynaptic terminus
B) Increasing the amount of neurotransmitter released from an action potential
C) Increasing the number of receptors on the postsynaptic membrane
D) Reducing voltage gated Na⁺ channels on the neuron

Question 50

Compare and contrast electrical synapses with chemical synapses, including advantages and disadvantages for each.

Question 51

Why were the terms nicotinic and muscarinic both used as names for the acetylcholine receptor?

Question 52

Briefly describe the mechanism of docking and fusion in the release of neurotransmitters.

Question 53

Explain why it is the receptor and not the neurotransmitter that determines whether the postsynaptic membrane produces an EPSP or an IPSP.

Question 54

Briefly explain the patch clamp technique and why it is important.

Question 55

How do most second messengers go on to affect the membrane potential?

Question 56

If Na⁺ and K⁺ move in opposite directions through the acetylcholine receptor (which has similar permeability to both ions) when it is bound to acetylcholine, why is there an overall depolarization instead of no change in the membrane potential?

Question 57

In two sentences, explain the overall mechanism of presynaptic facilitation (sensitization) in Aplysia.

Question 58

List three specific changes in the synapse that would be categorized as synaptic plasticity.