Ch. 13

Question 1

49. Which of the following 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.
    e. Increased intracellular Ca2+ leads to an increase of neurotransmitter release.

Answer 1

A

Question 2

3. What effect would injecting a leg muscle with a drug that binds to and disables acetylcholinesterase have on that leg?
   a. Delayed paralysis
   b. Immediate tetany
   c. Tetany once the leg muscle was contracted
   d. Paralysis once the leg muscle was contracted
   e. There would be no effect.

Answer 2

C

Question 3

39. When a superior cervical ganglion is heavily stimulated, how does it keep from running out of acetylcholine?
    a. Presynaptic inhibition occurs to conserve the acetylcholine.
    b. Acetylcholinesterase is inhibited by the increased amount of acetylcholine.
    c. More acetylcholine is created via second messenger systems.
    d. More choline is produced in the cleft and taken back up into the cell to create more acetylcholine.
    e. The superior cervical ganglion often runs out of acetylcholine.

Answer 3

D

Question 4

8. Epinephrine is
   a. excitatory.
   b. inhibitory.
   c. simultaneously excitatory and inhibitory.
   d. neither excitatory nor inhibitory.
   e. either excitatory or inhibitory.

Answer 4

E

Question 5

2. Which of the following statements regarding chemical synapses is false?
   a. Chemical synapses can be excitatory or inhibitory.
   b. Chemical synapses transmit information in only one direction.
   c. Chemical synapses have high plasticity.
   d. Pre- and postsynaptic currents are always similar.
   e. Neurotransmitters diffuse across the synapse.

Answer 5

D

Question 6

1. A specialized site of contact of one neuron with another neuron (or effector) is known as a
   a. neuron.
   b. receptor–neurotransmitter complex.
   c. muscle.
   d. membrane.
   e. synapse.

Answer 6

E

Question 7

30. 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.
    e. The receptor will pull off of the membrane.

Answer 7

D

Question 8

7. 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
   e. synapse

Answer 8

B

Question 9

38. Which second messenger acts directly to mediate the release of Ca2+ from the endoplasmic reticulum?
    a. Diacylglycerol (DAG)
    b. Inositol triphosphate (IP3)
    c. Protein kinase C
    d. Calmodulin
    e. Phospholipase C

Answer 9

B

Question 10

40. 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.
    e. deactivating serotonin.

Answer 10

C

Question 11

31. Which of the following statements 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.
    e. It has an affinity for binding acetylcholine.

Answer 11

C

Question 12

8. 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. Nothing will happen.
   c. An action potential will be produced.
   d. The potentials created will cancel each other out.
   e. There will be a depolarization but no action potential.

Answer 12

D

Question 13

1. Which of the following is most directly responsible for exocytosis of synaptic vesicles?
   a. Cl–
   b. Na+
   c. Acetylcholine
   d. K+
   e. Ca2+

Answer 13

E

Question 14

6. The limiting factor in the synthesis of acetylcholine is the
   a. speed at which acetyl groups are formed.
   b. speed at which vesicles are formed.
   c. frequency of the action potentials produced.
   d. speed at which choline is recycled.
   e. speed at which vesicles release choline.

Answer 14

D

Question 15

24. Which of the following statements 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.
    e. Calcium enters the cell.

Answer 15

D

Question 16

37. Which of the following 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
    e. All of the above are directly mediated by a G protein.

Answer 16

A

Question 17

13. During presynaptic inhibition, which of the following is true?
    a. A metabotropic response reduces the number of action potentials reaching the synapse.
    b. A metabotropic response reduces the amount of calcium entering the nerve terminus.
    c. An ionotropic response reduces the number of action potentials reaching the synapse.
    d. An ionotropic response reduces the amount of calcium entering the nerve terminus.
    e. None of the above

Answer 17

B

Question 18

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

Answer 18

Both electrical and chemical synapses can rapidly change the membrane potential of a postsynaptic cell. In electrical synapses, there is a direct electrical coupling that allows current flow to flow between cells with only negligible delay. While this provides a speed and synchronization advantage, there is low plasticity and directionality within these synapses. In chemical synapses, on the other hand, a presynaptic neuron releases a neurotransmitter, which diffuses across a synapse and binds to the postsynaptic receptor, causing a postsynaptic potential. While generally slower than the electrical synapse, the advantage of chemical synapses is their high plasticity, which gives them the ability to integrate neuronal functions.

Question 19

11. 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. postsynaptic reversal
    d. action potential
    e. voltage

Answer 19

B

Question 20

4. Ligand-gated channels on the postsynaptic membrane open and K+ and Na+ both move through these channels in opposite directions. Why then do we measure depolarization on the postsynaptic membrane?
   a. Na+ has a much stronger driving force into the cell.
   b. K+ has a much stronger driving force into the cell.
   c. Na+ has a much stronger driving force out of the cell.
   d. K+ has a much stronger driving force out of the cell.
   e. K+ moves out of the cell, then back into the cell.

Answer 20

A

Question 21

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

Answer 21

The two types of acetylcholine receptors were first characterized many years ago by their pharmacological response. The acetylcholine receptor in skeletal muscle is stimulated by nicotine and was hence named a nicotinic receptor. The acetylcholine receptor on the heart muscle is stimulated by muscarine and was thus named a muscarinic receptor.

Question 22

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

Answer 22

Serotonin acts via a G protein to upregulate cAMP, which activates cAMP-dependent protein kinases to phosphorylate the K+ channel. This leads to a decrease in the repolarizing K+ current, allowing Ca2+ channels to stay open longer, mediating a greater release of neurotransmitter per action potential.

Question 23

3. 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?

Answer 23

Although the acetylcholine channel has similar permeabilities to Na+ and K+, most of the synaptic current underlying the EPSP is created by Na+ movement. This is because the driving force for Na+ to enter the cell is far greater than the driving force for K+ to leave the cell.

Question 24

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

Answer 24

Whether the PSP is excitatory or inhibitory depends on what kinds of ions flow through the ion channels when the channels open. A particular neurotransmitter can act at different receptors, and they may produce similar effects or different effects.

Question 25

41. Synaptic efficacy is
    a. the relative amplitude of the postsynaptic potential in response to the presynaptic action potential.
    b. another word for synaptic plasticity.
    c. increased postsynaptic potential in response to the presynaptic action potential.
    d. the efficiency of release of neurotransmitter across the synapse.
    e. the speed at which the neurotransmitter is released and broken down in the synapse.

Answer 25

A

Question 26

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

Answer 26

a) Number of receptors on the postsynaptic membrane
b) Amount of neurotransmitter released per action potential
c) The effectiveness of the uptake or breakdown of the neurotransmitter once released into the synapse

Question 27

23. How do we account for the two hypotheses of vesicular fusion and retrieval?
    a. There is more experimental support for the classical pathway of NT release.
    b. There was very little support for the classical pathway of NT 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 NT release while the classical pathway predominates at higher rates of NT release.
    e. We cannot account for the existence of the two hypotheses of vesicular fusion and retrieval.

Answer 27

D

Question 28

35. 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.
    e. None of the above; we do not have any information regarding the evolutionary history of ligand-gated channels.

Answer 28

D

Question 29

42. 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. Slowing the breakdown of the neurotransmitter released in the synapse
    d. Increasing the number of receptors on the postsynaptic membrane
    e. Reducing voltage gated Na+ channels on the neuron

Answer 29

E

Question 30

19. Fast IPSPs result mainly from a(n) _______ in permeability to _______.
    a. decrease; Na+
    b. increase; Cl–
    c. increase; K+
    d. decrease; Ca2+
    e. increase; Na+

Answer 30

B

Question 31

7. The protein responsible for triggering the actual release of neurotransmitter at the synapse is
   a. synapsin.
   b. synaptotagmin.
   c. SNARE.
   d. dynamin.
   e. sytaxin.

Answer 31

B

Question 32

25. Which of the following 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 synaptotagmin.
    e. All of the above are true; none is false.

Answer 32

E

Question 33

46. Which of the following statements 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.
    e. Protein kinase phosphorylates Na+ channels and decreases the Na+ current that normally activates the action potential, which leads to an increase in Ca2+ influx.

Answer 33

B

Question 34

19. The induction of long-term potentiation occurs in
    a. the presynaptic neuron.
    b. the synapse.
    c. the postsynaptic neuron.
    d. the motor neuron.
    e. both the pre- and postsynaptic neurons.

Answer 34

C

Question 35

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

Answer 35

Docking is mediated by the formation of a SNARE complex; the v-SNAREs and t-SNAREs interact to hold the vesicle at the release site. Following priming, Ca2+ entry through voltage-gated Ca2+ channels triggers fusion by the binding of Ca2+ to the vesicular protein synaptotagmin. The Ca2+–synaptotagmin complex changes conformation to fuse the vesicular and terminal membranes.

Question 36

11. Which of the following statements about the neuromuscular junction acetylcholine (Ach) receptor is false?
    a. The probability an ACh channel will open depends on ACh concentration.
    b. The synaptic current is the sum of the net ionic currents through all activated ACh receptors.
    c. The opening of the ACh receptor is all-or-none.
    d. The probability that an ACh channel will open depends on membrane voltage.
    e. The current through a single receptor can be measured with a patch clamp technique.

Answer 36

D

Question 37

4. Which of the following is not found in the structure of the chemical synapse?
   a. Mitochondria
   b. Postsynaptic densities
   c. Synaptic vesicles
   d. Scaffolding proteins
   e. Connexons

Answer 37

E

Question 38

5. The main ion responsible for the EPSP is
   a. Na+.
   b. K+.
   c. Cl–.
   d. Ca2+.
   e. Cl– or K+.

Answer 38

A

Question 39

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 sodium.
    d. is inactivated by calcium.
    e. is broken down by acetylcholinesterase.

Answer 39

E

Question 40

17. What is the mechanistic explanation for sensitization?
    a. Decrease in chloride flux
    b. Increase in sodium flux
    c. Increase in potassium flux
    d. Decrease in potassium flux
    e. Increase in calcium flux

Answer 40

E

Question 41

22. 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.
    e. The extracellular fluid was made identical to the intracellular fluid so that action potentials would release few vesicles.

Answer 41

C

Question 42

21. A quantum is a
    a. count of the number of acetylcholine molecules in a vesicle.
    b. cholinergic neurotransmitter.
    c. measure of the total amount of acetylcholine released into the synapse.
    d. measure of the stored acetylcholine in the presynaptic terminal.
    e. vesicle in the synapse.

Answer 42

A

Question 43

20. Which of the following statements best describes long-term potentiation?
    a. More sodium entering the postsynaptic membrane per presynaptic action potential
    b. More neurotransmitter released per action potential
    c. More action potentials sent per second
    d. Action potentials display a larger depolarization
    e. More calcium released per action potential

Answer 43

A

Question 44

20. Which of the following distinguishes a standard neuromuscular EPSP from a miniature EPSP (mEPSP)?
    a. An excitatory postsynaptic potential.
    b. The movement of Na+ across the postsynaptic membrane.
    c. The diffusion of a neurotransmitter across the synapse.
    d. A depolarization caused by the release of a neurotransmitter.
    e. The postsynaptic response to the release of the contents of one synaptic vesicle.

Answer 44

E

Question 45

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

Answer 45

Most second messengers activate protein kinases, which phosphorylate proteins such as ion channels and change their permeability, which then alters the membrane potential.

Question 46

18. Calmodulin binds to _______ and becomes activated.
    a. Na+
    b. G protein
    c. Ca2+
    d. protein kinase C
    e. adenylyl cyclase

Answer 46

C

Question 47

47. Long-term potentiation has been extensively studied in
    a. the hippocampus.
    b. skeletal muscle.
    c. the hypothalamus.
    d. the neuromuscular junction.
    e. the cerebellum.

Answer 47

A

Question 48

26. Which of the following neurotransmitters elicits responses of both ionotropic and metabotropic receptors?
    a. Acetylcholine
    b. Dopamine
    c. Glutamate
    d. Both a and c
    e. All of the above

Answer 48

D

Question 49

13. Which of the following could not be the postsynaptic membrane mechanism during an inhibitory postsynaptic potential?
    a. Increase in the permeability to K+
    b. Increase in the permeability to Na+
    c. Increase in the permeability to Cl–
    d. Decrease in the permeability to Ca2+
    e. All of the above could produce an inhibitory postsynaptic potential.

Answer 49

B

Question 50

48. Which of the following occurrences 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

Answer 50

C

Question 51

9. Which of the following statements regarding vertebrate neurotransmitters is false?
   a. Most synapses (numerically) in the CNS use amino acid neurotransmitters.
   b. In the CNS, many receptors for biogenic amines mediate fast ionic responses.
   c. Biogenic amines are found in relatively few neurons in the CNS.
   d. A neuroactive peptide may be co-released with one or more small-molecule neurotransmitters and may function as a cotransmitter.
   e. Peptides are present in substantial numbers of CNS neurons.

Answer 51

B

Question 52

50. Which of the following 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 are smarter than standard lab mice.
    c. They produce more neurotransmitters than standard lab mice.
    d. They produce more action potentials per second than standard lab mice.
    e. They have a better, longer term memory than standard lab mice.

Answer 52

A

Question 53

3. In an electrical synapse, the main structure responsible for transmission of an impulse from one cell to the next is
   a. a strong depolarizing current.
   b. any generic activating neurotransmitter.
   c. acetylcholine.
   d. the gap junction.
   e. the cell membrane.

Answer 53

D

Question 54

16. In Aplysia, the result of sensitization at the synapse is a(n)
    a. decrease in the amount of neurotransmitter per impulse.
    b. increase in the number of impulses per second.
    c. increase in the number of channels binding the neurotransmitter.
    d. increase in the amount of neurotransmitter per impulse.
    e. decrease in the number of impulses per second.

Answer 54

D

Question 55

36. How does the G protein activate adenylyl cyclase?
    a. The G protein trimer attaches to adenylyl cyclase to activate it.
    b. The G protein mediates the release of cAMP-dependent protein kinase, which activates adenylyl cyclase.
    c. The G protein activates various second messengers, which all activate pathways that activate adenylyl cyclase.
    d. The α subunit of the G protein, with GTP, diffuses laterally in the membrane and binds to adenylyl cyclase to activate it.
    e. The G protein causes a depolarization, which activates adenylyl cyclase.

Answer 55

D

Question 56

10. Which of the following statements regarding metabotropic receptors is false?
    a. They can be a G protein–coupled receptor.
    b. They can directly open or close ion channels.
    c. They can activate a G protein.
    d. They usually use a second messenger.
    e. They mediate membrane voltage changes via slow postsynaptic potentials.

Answer 56

B

Question 57

28. The major excitatory neuromuscular junction neurotransmitter in a moth is
    a. acetylcholine.
    b. glutamate.
    c. glycine.
    d. GABA.
    e. glycogen.

Answer 57

B

Question 58

27. Which of the following is not known to be a neurotransmitter?
    a. Dopamine
    b. Glycogen
    c. GABA
    d. Glycine
    e. Glutamate

Answer 58

B

Question 59

14. Evaluate the following statement: “A neuron’s output is the same as its input.”
    a. True
    b. Mostly true
    c. Sometimes true, sometimes false
    d. Mostly false
    e. False

Answer 59

E

Question 60

6. In chemical synapses, neurotransmitters are released by
   a. facilitated diffusion.
   b. diffusion.
   c. calcium-dependent exocytosis.
   d. active transport.
   e. vesicular cycling.

Answer 60

C

Question 61

5. Which of the following is most uniquely associated with a metabotropic receptor?
   a. Neurotransmitter
   b. Second messenger
   c. Ligand-gated receptor
   d. Voltage-gated receptor
   e. Synaptic vesicle

Answer 61

B

Question 62

18. Which of the following statements regarding postsynaptic potentials is false?
    a. In a neuromuscular junction, the neurotransmitter is acetylcholine.
    b. In a CNS neural synapse, glycine produces an IPSP.
    c. In a CNS neural synapse, K+ is the main ion producing the EPSP.
    d. In a CNS neural synapse, GABA produces an IPSP.
    e. In a neuromuscular synapse, Na+ is the main ion producing the EPSP.

Answer 62

C

Question 63

15. What is the difference between synaptic facilitation and behavioral sensitization?
    a. Synaptic facilitation is a short term response and behavioral sensitization is a long term response.
    b. Synaptic facilitation is related to the sensory system and behavioral sensitization is related to the motor system.
    c. Synaptic facilitation underlies behavioral sensitization.
    d. They are both fundamentally the same thing.
    e. Synaptic facilitation depresses the stimulation, and behavioral sensitization sensitizes it.

Answer 63

C

Question 64

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

Answer 64

The patch clamp technique uses a fine glass microelectrode sealed the membrane with suction. The patch of membrane is then pulled from the cell and the researcher has the ability to alter the solution on either side of the membrane, as well as measure the receptor channel current. Because of its small size, researchers are able to measure the current on isolated receptors, which has been invaluable in advancing the field of receptor physiology and pharmacology.

Question 65

29. Which one of the following statements regarding neurotransmitters (NTs) is true?
    a. Small molecule NTs are synthesized mainly in the nucleus.
    b. Neuropeptides are released in response to low-frequency stimulation.
    c. Small molecule NTs are contained in large dense-cored vesicles.
    d. Neuropeptides are synthesized at the axon terminal.
    e. The inactivation of small molecule NTs can occur via reuptake or via enzymes.

Answer 65

E

Question 66

2. Which of the following transmits information the fastest?
   a. Ionotropic EPSP
   b. Metabotropic IPSP
   c. Electrical synapse
   d. Fast EPSP
   e. None of the above

Answer 66

C

Question 67

2. Compare and contrast ionotropic and metabotropic receptors

Answer 67

Ionotropic and metabotropic receptors are both found on the postsynaptic membrane of a chemical synapse and respond to the binding of a neurotransmitter. When bound to a neurotransmitter, ionotropic receptors directly alter permeability to ions, whereas metabotropic receptors trigger a signaling cascade of second messengers.

Question 68

12. Which of the following proteins cannot contact a G protein directly?
    a. Protein kinase C
    b. Potassium channel
    c. Phospholipase C
    d. Adenylyl cyclase
    e. Norepinephrine receptor

Answer 68

A