Chapter 18: Mechanisms of Extrasynaptic Communication

Test Bank

Type: multiple choice question

Title: Chapter 18 - Question 01

1. The three regions into which neurotransmitters are released extrasynaptically are the neuropil, the CSF, and the

Feedback: Subhead: Meaning of Extrasynaptic Communication for the Nervous System
Learning Objective: Name three regions into which neurons release transmitter extrasynaptically.
Bloom’s Level: 1. Remembering

a. blood stream.

b. cytoplasm.

c. synaptic cleft.

d. choroid plexus.

e. vesicles.

Type: multiple choice question

Title: Chapter 18 - Question 02

2. One result of the volume transmission method of extrasynaptic communication is that

Feedback: Subhead: Meaning of Extrasynaptic Communication for the Nervous System
Learning Objective: Define volume transmission.
Bloom’s Level: 3. Applying

a. extrasynaptic communication happens more quickly than synaptic communication.

b. the effects occur after a time-lag based on the distance to the receptors.

c. neurotransmitter reuptake is more efficient than in synaptic communication.

d. neurotransmitters are not packaged in vesicles prior to release.

e. extrasynaptic communication produces fast negative feedback.

Type: multiple choice question

Title: Chapter 18 - Question 03

3. A fundamental role of glial cells in extrasynaptic communication is to

Feedback: Subhead: Meaning of Extrasynaptic Communication for the Nervous System
Learning Objective: Discuss the role of glia in extrasynaptic neurotransmission.
Bloom’s Level: 2. Understanding

a. help transport dense-core vesicles from release sites to receptor sites.

b. put the ‘brakes’ on signaling by absorbing signaling molecules.

c. pass along messages by capturing and releasing signaling molecules.

d. help form electrical connections between one neuron and the next.

e. promote negative feedback by inhibiting neurons that release neurotransmitters.

Type: multiple choice question

Title: Chapter 18 - Question 04

4. In extrasynaptic communication, glial cells

Feedback: Subhead: Meaning of Extrasynaptic Communication for the Nervous System
Learning Objective: Discuss the role of glia in extrasynaptic neurotransmission.
Bloom’s Level: 2. Understanding

a. are the only cells capable of extrasynaptic neurotransmitter release.

b. work in coordination with neurons, with both capable of extrasynaptic neurotransmitter release.

c. provide the physical scaffolding needed for molecules to pass from one neuron to the next.

d. help construct a filter to prevent extrasynaptically released molecules from leaving the brain.

e. reduce the distance that signals can travel, by repackaging any molecules released outside of synapses.

Type: multiple choice question

Title: Chapter 18 - Question 05

5. Neurons that release a neurotransmitter extrasynaptically

Feedback: Subhead: Meaning of Extrasynaptic Communication for the Nervous System
Learning Objective: Not aligned
Bloom’s Level: 2. Understanding

a. do not contain synaptic structures.

b. also release the same neurotransmitter synaptically.

c. may release the same or other neurotransmitters synaptically.

d. may have synaptic structures, which use a different neurotransmitter.

e. neurons do not communicate extrasynaptically – only glial cells do.

Type: multiple choice question

Title: Chapter 18 - Question 06

6. In the lobster aggression system, the function of serotonin is such that serotonin

Feedback: Subhead: Early Evidence for Etrasynaptic Release of Transmitters
Learning Objective: Discuss how studies of aggression in the lobster led to key insights into how the nervous system works.
Bloom’s Level: 2. Understanding

a. is not involved in aggressive behaviors in lobsters.

b. reduces the probability of any dominant or submissive behaviors.

c. increases the probability of a backward walking escape.

d. increases the strength and duration of dominant displays.

e. is required for any aggressive behaviors to be observed.

Type: multiple choice question

Title: Chapter 18 - Question 07

7. The neurotransmitter responsible for ‘tuning’ the magnitude of aggressive displays in lobsters is

Feedback: Subhead: Early Evidence for Etrasynaptic Release of Transmitters
Learning Objective: Discuss how studies of aggression in the lobster led to key insights into how the nervous system works.
Bloom’s Level: 1. Remembering

a. octopamine.

b. serotonin.

c. acetylcholine.

d. glutamate.

e. adrenaline.

Type: multiple choice question

Title: Chapter 18 - Question 08

8. Experiments on extrasynaptic transmission using amperometry have demonstrated that

Feedback: Subhead: Meaning of Extrasynaptic Communication for the Nervous System
Learning Objective: Discuss how the identification of serotonergic and dopaminergic neurons in rodent brains provided early evidence for extrasynaptic transmission.
Bloom’s Level: 2. Understanding

a. quantal packages of transmitter are released from the cell bodies of neurons.

b. neurotransmitters are released extrasynaptically without the use of vesicles.

c. vesicles at the soma are larger than those released at dendritic projections.

d. neurotransmitters are released from dendritic projections but not from the cell body.

e. only monoamines are released extrasynaptically.

Type: multiple choice question

Title: Chapter 18 - Question 09

9. As a general rule, the mechanisms for extrasynaptic exocytosis

Feedback: Subhead: Mechanisms for Extrasynaptic Exocytosis
Learning Objective: Describe the four different types of extrasynaptic exocytosis.
Bloom’s Level: 2. Understanding

a. resemble exocytosis from gland cells in invertebrates, and resemble synaptic exocytosis in vertebrates.

b. have only been observed in vertebrates, and are similar to those of synaptic exocytosis.

c. are similar in invertebrates and vertebrates, and resemble exocytosis from gland cells.

d. resemble synaptic exocytosis in invertebrates, and resemble exocytosis from gland cells in vertebrates.

e. have only been observed in invertebrates, and are similar to exocytosis from gland cells.

Type: multiple choice question

Title: Chapter 18 - Question 10

10. Which of the options below is not a method of extrasynaptic exocytosis?

Feedback: Subhead: Mechanisms for Extrasynaptic Exocytosis
Learning Objective: Describe the four different types of extrasynaptic exocytosis.
Bloom’s Level: 1. Remembering

a. Somato-dendritic exocytosis

b. Axonal exocytosis

c. Perisynaptic exocytosis

d. Perivascular exocytosis

e. Spillover

Type: multiple choice question

Title: Chapter 18 - Question 11

11. Which of the options below is not a method of extrasynaptic exocytosis?

Feedback: Subhead: Mechanisms for Extrasynaptic Exocytosis
Learning Objective: Describe the four different types of extrasynaptic exocytosis.
Bloom’s Level: 2. Understanding

a. Fusion of large numbers of vesicles at the soma

b. Molecule release from clusters of vesicles from varicosities along non-myelinated axons

c. Molecules not stored in vesicles are gradually leaked from dendritic varicosities

d. Leak of excess transmitter from the synaptic cleft

e. Vesicles that are not part of the synaptic pool are released near presynaptic active zones

Type: multiple choice question

Title: Chapter 18 - Question 12

12. Dense-core vesicles are often found

Feedback: Subhead: Mechanisms for Extrasynaptic Exocytosis
Learning Objective: Distinguish between clear and dense-core vesicles.

Bloom’s Level: 2. Understanding

a. near somatic and perisynaptic release sites.

b. in the nucleus of dopaminergic neurons.

c. diffusing through the CSF.

d. in axon terminals of magnocellular neurons.

e. in retinal amacrine cells.

Type: multiple choice question

Title: Chapter 18 - Question 13

13. Magnocellular hypothalamic neurons release _______ from the axons or dendrites.

Feedback: Subhead: Mechanisms for Extrasynaptic Exocytosis
Learning Objective: Describe the two main procedures used to study peptide exocytosis in magnocellular neurons.
Bloom’s Level: 1. Remembering

a. either oxytocin or vasopressin

b. either dopamine or serotonin

c. acetylcholine

d. either epinephrine or norepinephrine

e. glutamate

Type: multiple choice question

Title: Chapter 18 - Question 14

14. Tannic acid can be added to neurons in order to

Feedback: Subhead: Mechanisms for Extrasynaptic Exocytosis
Learning Objective: Describe the two main procedures used to study peptide exocytosis in magnocellular neurons.
Bloom’s Level: 2. Understanding

a. produce fluorescence in peptides.

b. block the fusion of vesicles with the cell membrane.

c. count quanta of neurotransmitter released from different locations.

d. prevent reuptake of neurotransmitters.

e. visualize fusion of dense-core vesicles.

Type: multiple choice question

Title: Chapter 18 - Question 15

15. Studies of hypothalamic magnocellular neurons have used radioimmunoassay to show that

Feedback: Subhead: Mechanisms for Extrasynaptic Exocytosis
Learning Objective: Describe the two main procedures used to study peptide exocytosis in magnocellular neurons.
Bloom’s Level: 2. Understanding

a. vesicles may travel long distances from release sites to receptor sites.

b. magnocellular neurons are able to synthesize and release more than one peptide at once.

c. more vesicles are released at cell bodies than at dendrites.

d. trains of action potentials are needed to produce exocytosis.

e. extrasynaptic transmission uses dense-core, rather than clear, vesicles.

Type: multiple choice question

Title: Chapter 18 - Question 16
16. In magnocellular neurons of the hypothalamus, oxytocin released from dendrites

Feedback: Subhead: Mechanisms for Extrasynaptic Exocytosis
Learning Objective: Describe the two main procedures used to study peptide exocytosis in magnocellular neurons.
Bloom’s Level: 2. Understanding

a. mingles with synaptically released oxytocin to amplify its effects.

b. affects calcium release in neighboring neurons without altering electrical activity.

c. moves directly into the bloodstream for wide dissemination.

d. is sufficient to produce action potentials in neighboring neurons.

e. inhibits vesicle fusion at synaptic sites.

Type: multiple choice question

Title: Chapter 18 - Question 17

17. One similarity between extrasynaptic transmission and synaptic transmission is that

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Name three main ways in which the mechanism for somatic exocytosis differs from that for synaptic transmission.
Bloom’s Level: 2. Understanding

a. both occur with a time lag of seconds to tens of seconds.

b. in both cases, vesicles are stored and docked adjacent to the cell membrane.

c. both may transmit molecules across short or long distances to receptor sites.

d. both release signaling molecules from vesicles by exocytosis.

e. both can be stimulated by a single action potential in the releasing neuron.

Type: multiple choice question

Title: Chapter 18 - Question 18

18. In the somatic release sites of leech Retzius neurons, when exocytosis is not occurring,

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Identify the key structures at a somatic release site

Bloom’s Level: 2. Understanding

a. dense-core vesicles are linked to the plasma membrane by microtubules.

b. clear vesicles are stored in the nucleus until they are needed for exocytosis.

c. both dense-core and clear vesicles are docked on structures along the cell membrane.

d. dense-core vesicles and mitochondria are clustered along the inside of the cell membrane.

e. multivesicular bodies are stored in the nucleus until they are needed for exocytosis.

Type: multiple choice question

Title: Chapter 18 - Question 19

19. The fluorescent dye FM1-43 can be injected into the extracellular medium in order to visualize

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Explain how fluorescent dyes are used to quantify the amount of exocytosis in a Retzius neuron.

Bloom’s Level: 2. Understanding

a. the location where vesicles fuse to the plasma membrane.

b. microtubule transport systems.

c. monoamines in the extracellular space.

d. the location of mitochondria.

e. hormones in the blood stream.

Type: multiple choice question

Title: Chapter 18 - Question 20

20. A measure of “FM1-43 fluorescent spots” can be used to indicate

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Explain how fluorescent dyes are used to quantify the amount of exocytosis in a Retzius neuron.

Bloom’s Level: 2. Understanding

a. ATP levels.

b. depolarization.

c. oxygen use of a neuron.

d. amount and location of exocytosis.

e. intracellular calcium levels.

Type: multiple choice question

Title: Chapter 18 - Question 21

21. Electrical stimulation of leech Retzius neurons leads to

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Discuss the role of calcium in somatic exocytosis.

Bloom’s Level: 2. Understanding

a. exocytosis, but only with low frequency stimulation (e.g., 1 Hz).

b. transport of vesicles to the plasma membrane, but only with high-frequency stimulation (e.g., 20 Hz).

c. exocytosis that is independent of the frequency of stimulation.

d. opening of calcium channels, but only with low frequency stimulation (e.g., 1 Hz).

e. inactivation of calcium channels that is independent of the frequency of stimulation.

Type: multiple choice question

Title: Chapter 18 - Question 22

22. When measuring intracellular calcium levels of leech Retzius neurons, high-frequency stimulation (e.g. 20 Hz) of the neuron

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Discuss the role of calcium in somatic exocytosis.

Bloom’s Level: 2. Understanding

a. leads to a later, slower peak than low-frequency stimulation.

b. produces a jagged, shark-tooth pattern with low peaks.

c. leads to a faster, higher peak concentration than low-frequency stimulation.

d. produces a gradual, roughly linear increase in concentration.

e. has no measurable effect on calcium concentration.

Type: multiple choice question

Title: Chapter 18 - Question 23

23. L-type calcium channels, such as those found in the soma of leech Retzius neurons, are especially suitable for extrasynaptic signaling because they

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Discuss the role of calcium in somatic exocytosis.

Bloom’s Level: 3. Applying

a. open only after a lag of up to one second.

b. have a very high depolarization threshold for opening.

c. are permeable to magnesium as well as calcium.

d. inactivate rapidly after opening.

e. are not easily inactivated.

Type: multiple choice question

Title: Chapter 18 - Question 24

24. In leech Retzius neurons, microtubules and kinesin motors function to

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Describe the two complementary systems by which vesicles are transported to the plasma membrane.

Bloom’s Level: 2. Understanding

a. transport vesicles from the interior of the cell to the periphery.

b. transport vesicles from the nucleus to the axon terminals.

c. assist with reuptake and repackaging of vesicles.

d. dock vesicles to the cell membrane at release sites.

e. move receptors to active sites.

Type: multiple choice question

Title: Chapter 18 - Question 25

25. Which of the sequences below best characterizes the sequence of events for somatic exocytosis in the leech Retzius neuron?

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Explain how ATP and calcium are involved in vesicle transport.

Bloom’s Level: 3. Applying

a. Transport of vesicles to plasma membrane; fast calcium transient; exocytosis; internal calcium release

b. Fast calcium transient; transport of vesicles to plasma membrane; internal calcium release; exocytosis

c. Internal calcium release; transport of vesicles to plasma membrane; exocytosis; fast calcium transient

d. Fast calcium transient; internal calcium release; transport of vesicles to plasma membrane; exocytosis

e. Internal calcium release; fast calcium transient; transport of vesicles to plasma membrane; exocytosis

Type: multiple choice question

Title: Chapter 18 - Question 26

26. In the leech Retzius neuron, the direct effect of the fast calcium transient is to

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Explain how ATP and calcium are involved in vesicle transport.

Bloom’s Level: 2. Understanding

a. open sodium channels.

b. inactivate potassium channels.

c. induce synthesis of ATP.

d. depolarize the neuron.

e. bind to NMDA receptors.

Type: multiple choice question

Title: Chapter 18 - Question 27

27. Somatic exocytosis in the leech Retzius neuron is produced by intracellular calcium that is released in response to

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: List the three steps in the feedback loop that maintains large-scale somatic exocytosis

Bloom’s Level: 2. Understanding

a. dopamine.

b. acetylcholine.

c. octopamine.

d. serotonin.

e. oxytocin.

Type: multiple choice question

Title: Chapter 18 - Question 28

28. The sequence of events by which serotonin produces somatic exocytosis in the leech Retzius neuron can best be characterized as

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: List the three steps in the feedback loop that maintains large-scale somatic exocytosis

Bloom’s Level: 4. Analyzing

a. a negative feedback loop.

b. a positive feedback loop.

c. lateral inhibition.

d. a command center.

e. a central pattern generator.

Type: multiple choice question

Title: Chapter 18 - Question 29

29. Unlike the recycling of vesicles at synapses, recycling of vesicles for somatic exocytosis

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Describe how vesicle recycling in extrasynaptic exocytosis differs from that at synapses.

Bloom’s Level: 2. Understanding

a. occurs in the Golgi apparatus.

b. occurs in the endoplasmic reticulum.

c. occurs in the extracellular space.

d. does not occur.

e. while docked at the plasma membrane.

Type: multiple choice question

Title: Chapter 18 - Question 30

30. The main function of the Leech Retzius Neurons is to

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Not aligned
Bloom’s Level: 2. Understanding

a. initiate feeding behavior.

b. stimulate release of oxytocin and/or vasopressin.

c. synchronize motoneuron activity to command crawling behavior.

d. modulate aggressive behaviors.

e. inhibit release of octopamine.

Type: multiple choice question

Title: Chapter 18 - Question 31

31. A scientist is studying leech behavioral neurobiology. If she injects serotonin into the leech, what is the scientist likely to observe?

Feedback: Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons
Learning Objective: Not aligned
Bloom’s Level: 3. Applying

a. The leech will not react appropriately to social cues.

b. The leech will produce a dominant display.

c. The leech will begin feeding.

d. The leech will contract (shorten) and become immobile.

e. The leech will begin crawling.

Type: multiple choice question

Title: Chapter 18 - Question 32

32. An exosome is a

Feedback: Subhead: Coexisting Forms of Extrasynaptic Communication
Learning Objective: Distinguish between exosomes and endosomes.

Bloom’s Level: 2. Understanding

a. type of multivesicular body.

b. type of extracellular vesicle.

c. dense-core vesicle found in leech Retzius neurons.

d. tubulovesicular structure.

e. serotonin reuptake device.

Type: multiple choice question

Title: Chapter 18 - Question 33

33. Transmitter spillover effects originate with

Feedback: Subhead: Coexisting Forms of Extrasynaptic Communication
Learning Objective: Explain what spillover is and what effects it can have.

Bloom’s Level: 1. Remembering

a. glial cells.

b. leakage of neurotransmitter from somatic exocytosis.

c. leakage of neurotransmitter from synaptic exocytosis.

d. disintegration of extracellular vesicles.

e. blockade of calcium channels.

Type: multiple choice question

Title: Chapter 18 - Question 34

34. Dopamine is able to shift light sensitivity in the visual system by communicating with

Feedback: Subhead: Modulation of Visual Sensitivity and Blood Flow in the Retina
Learning Objective: Describe the role played by dopamine in modulating visual sensitivity in the retina.

Bloom’s Level: 2. Understanding

a. optic nerve activity.

b. muscles regulating pupil constriction.

c. capillary dilation.

d. photoreceptors.

e. horizontal and amacrine cells.

Type: multiple choice question

Title: Chapter 18 - Question 35

35. ATP acts on these cells in order to produce vasodilation in the retina.

Feedback: Subhead: Modulation of Visual Sensitivity and Blood Flow in the Retina
Learning Objective Describe the role played by ATP in modulating blood flow in the retina.

Bloom’s Level: 1. Remembering

a. Retzius neurons

b. Amacrine cells

c. Müller cells

d. Ependymal cells

e. Magnocellular neurons

Type: multiple choice question

Title: Chapter 18 - Question 36

36. The structure of Müller cells is specialized in that

Feedback: Subhead: Modulation of Visual Sensitivity and Blood Flow in the Retina
Learning Objective Discuss some of the key properties of Müller cells.

Bloom’s Level: 2. Understanding

a. their end feet wrap around capillaries.

b. their cilia protrude into the CSF.

c. they contain photopigments.

d. they change in diameter in response to light.

e. they contain multivesicular bodies.

Type: multiple choice question

Title: Chapter 18 - Question 37

37. When a Müller cell is stimulated with ATP, this leads to

Feedback: Subhead: Modulation of Visual Sensitivity and Blood Flow in the Retina
Learning Objective: List the key steps in the retinal metabolic pathway from glia to blood vessel contraction.

Bloom’s Level: 2. Understanding

a. influx of Na⁺ followed by an action potential.

b. the production of IP₃ and release of intracellular calcium.

c. phosphorylation and inactivation of potassium channels.

d. the release of dopamine into the CSF.

e. somatic exocytosis.

Type: multiple choice question

Title: Chapter 18 - Question 38

38. The exchange of molecules across the ependymal cell layer is central to the process of

Feedback: Subhead: Cerebrospinal Fluid as a Source of Volume Transmission
Learning Objective: Name the three complementary phenomena that enable the CSF to allow long-distance communication between brain regions.

Bloom’s Level: 3. Applying

a. swimming behavior in leeches.

b. social dominance in lobsters.

c. light and dark adaptation.

d. long-distance communication via the CSF.

e. vasodilation in the retina.

Type: multiple choice question

Title: Chapter 18 - Question 39

39. The movement of signaling molecules through the CSF represents one example of

Feedback: Subhead: Cerebrospinal Fluid as a Source of Volume Transmission
Learning Objective: Name the three complementary phenomena that enable the CSF to allow long-distance communication between brain regions

Bloom’s Level: 2. Understanding

a. volume transmission.

b. synaptic transmission.

c. retrograde messaging.

d. second messenger systems.

e. extrasynaptic potentiation.

Type: multiple choice question

Title: Chapter 18 - Question 40

40. Ependymal cells are primarily found

Feedback: Subhead: Cerebrospinal Fluid as a Source of Volume Transmission
Learning Objective: Explain what the ependymal cell layer is.

Bloom’s Level: 2. Understanding

a. lining the central canal of the spinal cord and the ventricles.

b. in the retina.

c. in the hypothalamus.

d. in the leech abdomen.

e. in the drosophila neuromuscular junction.

Type: multiple choice question

Title: Chapter 18 - Question 41

41. Which of the options below is not a feature of one or more of the ependymal cell types?

Feedback: Subhead: Cerebrospinal Fluid as a Source of Volume Transmission
Learning Objective: Name the four major cell types in the ependymal cell layer.

Bloom’s Level: 2. Understanding

a. Cilia that help drive movement of the CSF

b. Production of CSF

c. End feet that wrap around capillaries

d. Endocytosis of molecules from the CSF

e. Projections that release molecules into the neuropil

Type: multiple choice question

Title: Chapter 18 - Question 42

42. The three processes contributing to the exchange of signaling molecules between the CSF and the CNS include: diffusion via perivascular pumping, selective uptake and release by neuronal structures, and

Feedback: Subhead: Cerebrospinal Fluid as a Source of Volume Transmission
Learning Objective: List the three ways in which the CSF and the CNS exchange signaling molecules.

Bloom’s Level: 1. Remembering

a. cilial beating by Müller cells.

b. release of molecules into the blood stream.

c. diffusion over short distances.

d. endocytosis of molecules from the CSF.

e. somatic exocytosis.

Type: multiple choice question

Title: Chapter 18 - Question 43

43. A primary function of perivascular pumping is to

Feedback: Subhead: Cerebrospinal Fluid as a Source of Volume Transmission
Learning Objective: Explain what perivascular pumping is.

Bloom’s Level: 2. Understanding

a. transmit ATP to Müller cells.

b. stimulate mechanosensory cilia on ependymal cells.

c. modulate the rate of blood flow in the retina.

d. increase the rate at which molecules can move through the CSF.

e. increase oxygen levels in the CSF.

Type: essay/short answer question

Title: Chapter 18 - Question 44

44. Briefly explain what volume transmission is.

Feedback: Volume transmission occurs when signaling molecules are released from a site at some distance from the receptor site. The strength of response at the receptor site depends on the quantity released and the rate of diffusion.
Subhead: Meaning of Extrasynaptic Communication for the Nervous System
Learning Objective: Define volume transmission.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 18 - Question 45

45. Describe the role of serotonin on aggressive displays by lobsters.

Feedback: While aggressive behaviors can still be observed in the absence of serotonin, the injection of serotonin produces dominant posturing. Serotonin is not strictly required for aggression but may activate circuits that determine the duration and intensity of dominance displays.
Subhead: Early Evidence for Extrasynaptic Release of Transmitters
Learning Objective: Discuss how studies of aggression in the lobster led to key insights into how the nervous system works.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 18 - Question 46

46. Describe one method used by researchers to determine where extrasynaptic transmission occurs.

Feedback: One method is to use histology to detect yellow fluorescence produced by biogenic amines including serotonin and dopamine. By visualizing where these neurotransmitters are concentrated, researchers are able to observe high levels of these transmitters near release sites outside of standard synaptic terminals.
Subhead: Early Evidence for Extrasynaptic Release of Transmitters
Learning Objective: Discuss how the identification of serotonergic and dopaminergic neurons in rodent brains provided early evidence for extrasynaptic transmission.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 18 - Question 47

47. What signaling molecules are released by magnocellular hypothalamic neurons, and from where are they released?

Feedback: Magnocellular hypothalamic neurons may release either oxytocin or vasopressin, and these may be released from either the axons or the dendrites.
Subhead: Mechanisms for Extrasynaptic Exocytosis

Learning Objective: Describe the two main procedures used to study peptide exocytosis in magnocellular neurons.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 18 - Question 48

48. What is the role of L-type calcium channels in the leech Retzius neuron?

Feedback: Calcium is essential to somatic exocytosis in leech Retzius neurons. The L-type calcium channels are slow to inactivate, which allows prolonged calcium influx during extended stimulation. These receptors are responsible for the majority of the fast calcium transient that precedes somatic exocytosis.

Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons

Learning Objective: Discuss the role of calcium in somatic exocytosis.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 18 - Question 49

49. What are the three steps in the feedback loop that helps to maintain somatic exocytosis in leech Retzius neurons?

Feedback: First, serotonin that was initially released binds to type 2 autoreceptors on the neuron. Second, this activates phospholipase C, which synthesizes IP₃, triggering release of intracellular calcium stores. Third, release of calcium leads to further exocytosis of serotonin, which returns the loop to step 1.

Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons

Learning Objective: List the three steps in the feedback loop that maintains large-scale somatic exocytosis.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 18 - Question 50

50. What is one way in which recycling of dense core vesicles during extracellular exocytosis differs from recycling in standard synaptic transmission?

Feedback: One difference is in the location; recycling for synaptic transmission typically occurs in the axon terminal, while recycling of dense-core vesicles during somatic exocytosis occurs at the Golgi apparatus.

Subhead: Mechanism for Somatic Exocytosis of Serotonin in Leech Retzius Neurons

Learning Objective: Describe how vesicle recycling in extrasynaptic exocytosis differs from that at synapses.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 18 - Question 51

51. What are “tripartite synapses” and how are they involved in extrasynaptic communication?

Feedback: “Tripartite synapses” refer to the inclusion of glial cells in synaptic signaling. A “tripartite synapse” includes a pre-synaptic neuron, a post-synaptic neuron, and neighboring glia. The glia are stimulated as a result of spillover effects from synaptically released neurotransmitters.

Subhead: Coexisting Forms of Extrasynaptic Communication

Learning Objective: Explain what spillover is and what effects it can have.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 18 - Question 52

52. Explain how spillover effects contribute to extrasynaptic communication.

Feedback: Spillover effects use neurotransmitters that originated in the synapse, but that were not taken back up, or broken down, in the synapse and leaked away. Higher levels of synaptic release may produce greater spillover.
Subhead: Coexisting Forms of Extrasynaptic Communication

Learning Objective: Explain what spillover is and what effects it can have.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 18 - Question 53

53. Briefly describe the function of extrasynaptic dopamine release in the retina.

Feedback: Shining light onto the retina leads to extrasynaptic release of dopamine from amacrine cells. This dopamine acts on horizontal cells, resulting in the uncoupling of electrical connections between these cells, and also reduces connections between the rod and cone pathways. This serves to reduce sensitivity and produce sharper vision under bright conditions.

Subhead: Modulation of Visual Sensitivity and Blood Flow in the Retina

Learning Objective: Describe the role played by dopamine in modulating visual sensitivity in the retina.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 18 - Question 54

54. What is the function of Müller cells in the retina?

Feedback: Müller cells are a type of glial cell in the retina. They have end feet which wrap around capillaries. When ATP binds to these cells, IP3 is produced which leads to intracellular calcium release. This results in vasodilation near the stimulated cells.

Subhead: Modulation of Visual Sensitivity and Blood Flow in the Retina

Learning Objective: Discuss some of the key properties of Müller cells.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 18 - Question 55

55. Name two types of glial cells involved in extrasynaptic communication, and briefly explain what those cells do.

Feedback: Müller cells in the retina are one kind of glial cell involved in extrasynaptic communication. The function of Müller cells is to modulate blood flow through retinal capillaries, regulating the supply of oxygen and glucose to neurons. Another type of glial cells are those in the ependymal cell layer between the CNS and CSF. These ependymal cells facilitate the exchange of molecules between the CNS and the CSF.
Subhead: Modulation of Visual Sensitivity and Blood Flow in the Retina

Learning Objective: Discuss some of the key properties of Müller cells.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 18 - Question 56

56. What three components allow the CSF to enable long-distance signal transmission?

Feedback: The first component is the release of neurotransmitters, peptides, and other signaling molecules into the CSF. The second component is the continuous flow of CSF aided by the beating of ependymal cell cilia. The third is the exchange of molecules between the CSF and the CNS via the ependymal cell layer.

Subhead: Cerebrospinal Fluid as a Source of Volume Transmission

Learning Objective: Name the three complementary phenomena that enable the CSF to allow long-distance communication between brain regions

Bloom’s Level: 1. Remembering

Type: essay/short answer question

Title: Chapter 18 - Question 57

57. What is the function of the ependymal cell layer?

Feedback: The ependymal cell layer lines the ventricles and the central canal of the spinal cord. Ependymal cells are a type of glia that facilitate transmission of signaling molecules between the CNS and the CSF. Ependymal cells also project cilia into the CSF that help to determine the speed and direction of its flow.

Subhead: Cerebrospinal Fluid as a Source of Volume Transmission

Learning Objective: Explain what the ependymal cell layer is.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 18 - Question 58

58. What are the three ways that the CNS and CSF exchange signaling molecules?

Feedback: The first way is simple diffusion over short distances. The second way is diffusion over longer distances by means of perivascular pumping. The third way is selective uptake and release by neuronal structures in contact with the CSF.

Subhead: Cerebrospinal Fluid as a Source of Volume Transmission

Learning Objective: List the three ways in which the CSF and the CNS exchange signaling molecules.

Bloom’s Level: 1. Remembering