Florida International University

BIO PCB 4023

Chapter 8

1)For cells that communicate by electrical synapses, the message travels between cells via

1. 1. gap junctions.
   2. ions moving across the synaptic cleft.
   3. the diffusion of neurotransmitters.
   4. active transport across the synaptic cleft.
   5. passive transport across the synaptic cleft.
2. Which of the following statements about synapses is FALSE?
   1. Communication across electrical synapses is bi-directional.
   2. Electrical synapses can be gated.
   3. Most synapses in the nervous system are chemical synapses.
   4. Neurotransmitters can move from one cell to another through gap junctions at an electrical synapse.
   5. Communication at chemical synapses is slower than at electrical synapses.
3. Which of the following statements about electrical synapses is FALSE?
   1. Electrical synapses are usually for small-response, single neuron firing.
   2. Gap junctions are formed from proteins called connexins.
   3. Electrical synapses connect hypothalamic neurons that release tropic hormones.
   4. Electrical synapses are found in the brainstem.
   5. Electrical synapses are found in the retina.
4. 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.
   1. presynaptic : postsynaptic
   2. presynaptic : parasynaptic
   3. postsynaptic : presynaptic
   4. terminal : presynaptic
   5. parasynaptic : postsynaptic
5. What type of synapse occurs between an axon terminal of one neuron and the axon from another neuron?
   1. axoaxonic
   2. dendroaxonic
   3. somatoaxonic
   4. axosomatic
   5. axodendritic
6. What type of synapse occurs between an axon terminal of one neuron and the cell body of another neuron?
   1. axoaxonic
   2. dendroaxonic
   3. axodendritic
   4. axosomatic
   5. somatoaxonic

1

7. The neurotransmitter that is released from the presynaptic neuron must diffuse across the    to reach the postsynaptic neuron.
   1. axon
   2. axon hillock
   3. dendrite
   4. synaptic cleft
   5. cell body
8. What type of ion channels is necessary for the function of the axon and the axon terminal?
   1. voltage-gated

8. 2. receptor-gated
   3. chemically-gated
   4. ligand-gated
   5. mechanically-gated
9. Synaptic vesicles store
   1. sodium.
   2. potassium.
   3. calcium.
   4. neurotransmitter.
   5. enzymes that degrade neurotransmitter.
10. Most neurotransmitters are synthesized in what region of a neuron?
    1. cytosol of the axon terminal
    2. rough endoplasmic reticulum
    3. synaptic vesicles
    4. axon hillock
    5. Golgi apparatus
11. Neurotransmitter release occurs by what mechanism?
    1. exocytosis
    2. secondary active transport
    3. diffusion
    4. endocytosis
    5. primary active transport
12. Voltage-gated calcium channels in the axon terminal open in response to which of the following?
    1. arrival of an action potential at the axon terminal
    2. summation of graded potentials at the axon hillock
    3. paracrines released from the post-synaptic cell
    4. initiation of an action potential in the axon hillock
    5. neurotransmitter binding to receptor

2

13. The influx of calcium into the axon terminal of a chemical synapse is responsible for which of the following?
    1. initiation of an action potential
    2. fusion of vesicles to the membrane and of exocytosis neurotransmitter
    3. diffusion of the neurotransmitter across the membrane and into the cleft
    4. termination of an action potential
    5. movement of calcium through gap junctions
14. Which of the following is NOT a mechanism whereby neurotransmitters are rapidly removed from the synaptic cleft?
    1. active reuptake across the presynaptic membrane
    2. transport back up the axon to be immediately repackaged
    3. binding to the receptor
    4. diffusion out of the cleft
    5. degradation by enzymes
15. Neurotransmitters can be reused through the process of          , where neurotransmitters are transported back across the presynaptic membrane.
    1. recycling
    2. regeneration
    3. resynthesis
    4. reuptake
    5. receptor binding

16. The extent of neurotransmitter binding to receptors on the postsynaptic membrane is determined primarily by which of the following?
    1. the concentration of neurotransmitter
    2. the distance of the cleft
    3. calcium
    4. neurotransmitter vesicles
    5. sodium
17. The synaptic delay is caused by the time required for which step of neurotransmitter release?
    1. calcium entry to trigger exocytosis
    2. the synthesis of neurotransmitter
    3. an action potential to move from axon hillock to axon terminal
    4. packaging of neurotransmitter into synaptic vesicles
    5. the neurotransmitter to diffuse across the synaptic cleft

3

18. What type of receptor is responsible for the rapid opening of ion channels in response to the interaction between the ligand and receptor?
    1. mechanotropic
    2. metabotropic
    3. potentiotropic
    4. chemotropic
    5. ionotropic
19. The action of any chemical messenger ultimately depends not on the nature of the messenger, but rather on the
    1. nerve cell stimulated.
    2. organ system activated.
    3. half-life of the messenger.
    4. affinity of the receptor.
    5. signal transduction mechanism activated.
20. The rapid change in membrane potential that occurs when a ligand binds to an ionotropic receptor is caused by which of the following?
    1. the rapid G protein response that indirectly links receptor to channel
    2. the G protein amplification that causes the rapid channel response
    3. the large ion gradient across the membrane
    4. the rapid gating of the ion channel by G protein
    5. the presence of that protein functioning as both an ionotropic receptor and as the ion channel
21. Synaptic potentials are produced at what type of synapse?
    1. axoaxonic, axodendritic, and axosomatic synapses
    2. axoaxonic and axodendritic synapses only
    3. axoaxonic and axosomatic synapses only
    4. pre-axon hillock synapses only
    5. axodendritic synapses only
22. At metabotropic receptors, a(n)
    1. neurotransmitter binding to a receptor stimulates a G-protein, which then activates a second messenger through one or more enzymatic actions.
    2. ion binding to a receptor opens channels in the plasma membrane.
    3. neurotransmitter binding to a receptor opens channels that are a separate protein from the receptor.
    4. neurotransmitter binding to a receptor opens or closes channels that are part of the same protein as the receptor.
    5. neurotransmitter binding to a receptor opens or closes channels that are a separate protein from the

receptor.  4

23. Presynaptic modulation occurs at what type of synapse?
    1. axodendritic
    2. axoaxonic
    3. axosomatic
    4. dendrodendritic
    5. dendrosomatic
24. Metabotropic receptor-induced gating of ion channels requires more time to occur because of which of the following?
    1. The channels are slower to open.
    2. Their gating is linked to a G protein.
    3. Metabolic byproducts are required to open those channels.
    4. Intracellular calcium must increase before those channels will open.
    5. Ion channels linked to metabotropic receptors must move to the membrane before gating.
25. What is a change in the postsynaptic potential that brings membrane potential closer to threshold called?
    1. suprathreshold postsynaptic potential
    2. inhibitory postsynaptic potential
    3. inhibitory presynaptic potential
    4. excitatory postsynaptic potential
    5. hyperpolarizing postsynaptic potential
26. The most common mechanism for producing a fast EPSP involves which of the following?
    1. closing of potassium-selective channels
    2. opening of potassium-selective channels
    3. closing of sodium-selective channels
    4. opening of sodium-selective channels
    5. opening of channels that permit both sodium and potassium to flow through
27. What ion directly triggers neurotransmitter release from the presynaptic neuron?
    1. sodium B) potassium C) magnesium D) calcium E) chloride
28. An example of a slow excitatory postsynaptic potential that involves closure of potassium channels relies on cAMP produced by what enzyme?
    1. adenylate cyclase
    2. phosphodiesterase
    3. protein kinase A
    4. protein kinase C
    5. G protein  5
29. 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?
    1. protein kinase A
    2. G protein
    3. protein kinase C
    4. adenylate cyclase
    5. phosphodiesterase
30. Fast excitatory responses not only occur quickly, but they
    1. are maintained for minutes to hours.
    2. always create a substantial depolarization.
    3. remain active for a long period of time.

30. 4. end quickly.
    5. also have a slow component.
31. The binding of a neurotransmitter to its receptor at an inhibitory synapse can lead to the     of

              channels.

31. 1. opening : chloride
    2. closure : chloride
    3. opening : sodium
    4. closure : potassium
    5. opening : calcium
32. The binding of a neurotransmitter to its receptor at an inhibitory synapse can lead to the     of

              channels.

32. 1. closure : potassium
    2. opening : potassium
    3. opening : calcium
    4. closing : chloride
    5. opening : sodium
33. 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?
    1. net movement of chloride into the cell
    2. net movement of chloride out of the cell
    3. depolarization of the cell
    4. absence of any chloride movement
    5. movement of chloride equally in both directions

6

34. In the presence of active chloride ion transport within a neuron, the opening of chloride channels will result in which of the following?
    1. net movement of chloride into the cell
    2. net movement of chloride out of the cell
    3. depolarization of the cell
    4. absence of any chloride movement
    5. movement of chloride equally in both directions
35. If the resting membrane potential is equal to chloride's equilibrium potential, in which direction will chloride ions move if chloride channels open while the cell remains at resting membrane potential?
    1. inward
    2. outward
    3. No ions will move through the channel.
    4. Ions will move equally in both directions.
    5. Three chloride ions will move out for every two chloride ions that move in.
36. In the absence of an active chloride transporter in the plasma membrane, chloride acts to  

membrane potential by resisting any change in membrane potential.

36. 1. depolarize
    2. hyperpolarize
    3. stabilize
    4. alter
    5. modify
37. The opening of a chloride channel acts to   the development of an action potential at the axon hillock.
    1. facilitate B) stimulate C) further D) inhibit E) enhance

38. Convergence in neurophysiology refers to which of the following?
    1. the summation of graded potentials to determine whether or not an action potential will be generated
    2. the level of depolarization required to generate an action potential
    3. the presence of EPSPs and IPSPs on a neuron at the same time
    4. the communication of several neurons to one postsynaptic cell
    5. the arrival of an action potential at the axon terminal
39. The final integration of postsynaptic potentials that determines whether an action potential is generated occurs within what region of a neuron?
    1. axon hillock
    2. dendrites
    3. cell body
    4. rough endoplasmic reticulum
    5. axon  7
40. Divergence in neurophysiology refers to which of the following?
    1. the presence of EPSPs and IPSPs on a neuron at the same time
    2. the arrival of an action potential at the axon terminal
    3. the summation of graded potentials to determine whether or not an action potential will be generated
    4. the level of depolarization required to generate an action potential
    5. the communication of one neuron to several postsynaptic cells
41. For ionotropic receptors, their      response            the likelihood that two pulses from the same neuron will summate.
    1. slow : increases
    2. rapid : decreases
    3. rapid : does not affect
    4. rapid : increases
    5. slow : decreases
42. Which of the following would increase the likelihood of an action potential being generated in a postsynaptic cell?
    1. opening of potassium channels on the postsynaptic cell
    2. presynaptic inhibition at an excitatory synapse
    3. opening of chloride channels on a postsynaptic cell with no active transport of chloride ions
    4. presynaptic excitation at an excitatory synapse
    5. opening of chloride channels on a postsynaptic cell that actively transports chloride ions out of the cell
43. Which of the following statements about inhibitory synapses is FALSE?
    1. Opening of chloride channels can generate an IPSP.
    2. Opening of potassium channels can generate an IPSP.
    3. The membrane potential of the postsynaptic cell can be hyperpolarized.
    4. In presynaptic inhibition, the lower level potential generated interferes with the oncoming action potential.
    5. The postsynaptic cell is less likely to generate an action potential.
44. How does temporal summation create an action potential?
    1. It is frequency modulated and of the same amplitude for intensity.
    2. Two or more postsynaptic potentials are generated in rapid succession at the same synapse before they can dissipate, thereby exceeding threshold.
    3. Potentials are generated on several dendrites at the same time to trigger threshold and the production of an action potential.
    4. The temporal lobe in the brain stimulates EPSPs to trigger an action potential.
    5. Generator potentials are at the same tempo on adjacent neurons.

8

45. 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.
    1. decrease : frequency
    2. increase : amplitude
    3. decrease : amplitude
    4. not be altered : amplitude
    5. increase : frequency
46. 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.
    1. multiple : amplitude coding
    2. a single : amplitude coding
    3. a single : frequency coding
    4. multiple : frequency coding
    5. several : amplitude coding
47. Axoaxonic synapses are responsible for     the extent of neurotransmitter released at the synapse.
    1. increasing B) modulating C) decreasing D) inhibiting E) enhancing
48. Presynaptic modulation of neurotransmitter release involves modifying         at the axon terminal.
    1. membrane potential
    2. calcium influx
    3. the vesicles selected for release
    4. potassium channels
    5. sodium channels
49. During presynaptic inhibition, the release of a neurotransmitter from the modulating neuron causes which of the following?
    1. an increase in neurotransmitter release from the neuron it is modulating
    2. an EPSP on the postsynaptic cell
    3. a hyperpolarization of the neuron it is modulating
    4. an IPSP on the postsynaptic cell
    5. a decrease in calcium entry into the axon terminal of the neuron it is modulating
50. Which of the following BEST describes presynaptic facilitation?
    1. The modulating neuron causes an EPSP on the postsynaptic cell.
    2. The modulating neuron triggers an action potential in the postsynaptic cell.
    3. The modulating neuron decreases the effective communication between the cell it is modulating and its postsynaptic cell.
    4. The modulating neuron enhances neurotransmitter release to the postsynaptic cell.
    5. The modulating neuron stabilizes the membrane potential of the postsynaptic cell.

9

51. The synthesis of acetylcholine involves an enzyme called          , which is present within the axonal cytosol and is responsible for converting    into acetylcholine + CoA.
    1. acetylcholinesterase : choline
    2. acetylcholinesterase : acetyl CoA + choline
    3. choline acetyl transferase : choline + acetate
    4. choline acetyl transferase : acetyl CoA + choline
    5. choline acetyl transferase : acetyl CoA
52. Neurons that synthesize and release acetylcholine are called   neurons.
    1. dopaminergic
    2. cholinergic
    3. adrenergic

52. 4. gamma
    5. ACTH
53. Once released, acetylcholine is degraded by extracellular enzymes into what product(s)?
    1. methylcholine + acetate
    2. acetate only
    3. choline only
    4. acetate + choline
    5. acetyl CoA + choline
54. What is transported back into the axon terminal of cholinergic neurons to be resynthesized into active neurotransmitter?
    1. acetate
    2. choline
    3. acetylcholine
    4. acetyl CoA
    5. epinephrine
55. What type of receptor is both ionotropic and cholinergic?
    1. serotonergic
    2. adrenergic
    3. nicotinic
    4. muscarinic
    5. dopaminergic
56. What type of receptor is both metabotropic and cholinergic?
    1. adrenergic
    2. serotonergic
    3. nicotinic
    4. dopaminergic
    5. muscarinic

10

57. Which of the following is a neurotransmitter that contains a six-carbon ring with two hydroxyl groups and an amine group?
    1. neuroactive peptides
    2. nitric oxide
    3. amino acids
    4. acetylcholine
    5. norepinephrine
58. Which of the following couplings between neurotransmitter and neurotransmitter class is INCORRECT?
    1. adenosine : amino acid
    2. enkephalin : neuropeptide
    3. norepinephrine : catecholamine
    4. histamine : biogenic amine
    5. nitric oxide : gas
59. Histamine has receptors in the hypothalamus, RAS system, stomach, blood vessels, and bronchioles. What creates histamine's differing effects seen in each of these areas?
    1. There are different message transduction systems.
    2. Each tissue is different, so no two can have the same effect.
    3. Histamine recombines with other endogenous substances once inside the target cell.
    4. All of the effects are a result of membrane dehydration.
    5. They are dependent on which cell secretes the histamine.

60. Biogenic amines are synthesized in what region of a neuron?
    1. extracellular space
    2. axon hillock
    3. cytosol of the axon terminal
    4. rough endoplasmic reticulum
    5. cytosol of the cell body
61. The action of adrenergic receptors identifies them as   receptors.
    1. ionotropic
    2. mechanically-gated
    3. metabotropic
    4. voltage-gated
    5. chemotropic
62. Which of the following is a biogenic amine that is NOT classified as a catecholamine?
    1. adrenaline
    2. norepinephrine
    3. epinephrine
    4. serotonin
    5. dopamine  11
63. What two enzymes catalyze the breakdown of catecholamines?
    1. monoamine oxidase and phenylethanolamine N methyltransferase
    2. catechol-O-methyltransferase and acetylcholinesterase
    3. dopa decarboxylase and phenylethanolamine N methyltransferase
    4. acetylcholinesterase and dopa decarboxylase
    5. monoamine oxidase and catechol-O-methyltransferase
64. Epinephrine binds best to which of the following receptor types?
    1. alpha1 adrenergic receptors
    2. alpha2 adrenergic receptors
    3. alpha3 adrenergic receptors
    4. beta1 adrenergic receptors
    5. beta2 adrenergic receptors
65. Fast EPSPs are produced at which of the following types of receptor?
    1. nicotinic cholinergic only
    2. alpha-adrenergic only
    3. AMPA receptors only
    4. both nicotinic cholinergic and AMPA receptors
    5. both nicotinic cholinergic and alpha-adrenergic receptors
66. Histidine, tyrosine, and tryptophan all go on to become what class of neurotransmitters?
    1. purines
    2. biogenic amines
    3. amino acid transmitters
    4. catecholamines
    5. neuropeptides
67.               is an amino acid neurotransmitter at excitatory synapses whereas    is an amino acid neurotransmitter at inhibitory synapses.
    1. Glycine : aspartate
    2. Glutamate : aspartate
    3. Gamma-aminobutyric acid : glycine
    4. Aspartate : glycine

67. 5. Gamma-aminobutyric acid : glutamate
68. Which of the following GABA receptor types is coupled to chloride channels?
    1. GABAA only
    2. GABAB only
    3. GABAC only
    4. both GABAA and GABAB
    5. both GABAA and GABAC

12

69. Why are amino acid neurotransmitters NOT considered biogenic amines?
    1. Amino acids lose their activity when stored, while biogenic amines do not.
    2. Amino acids used to make biogenic amines are not used for anything else.
    3. Biogenic amines still contain an amine group, but are no longer amino acids.
    4. Amino acids are excitatory only, while biogenic amines are not.
    5. Biogenic amines may be taken up by non-conducting cells, while amino acids are not.
70. What is the most common inhibitory neurotransmitter in the central nervous system?
    1. acetylcholine
    2. glycine
    3. glutamate
    4. GABA
    5. aspartate
71. Neuropeptides are synthesized in what region of a neuron?
    1. within the axon terminal
    2. at the dendrite
    3. along the axon
    4. in the rough endoplasmic reticulum
    5. within the vesicles
72. Which of the following compounds is NOT a neuropeptide?
    1. vasopressin
    2. epinephrine
    3. endorphin
    4. substance P
    5. oxytocin
73. Which of the following is a hypothalamic neuropeptide that regulates the sleep-wake cycle?
    1. substance P B) oxytocin C) melatonin D) orexin E) vasopressin
74. Nitric oxide is a(n)           that functions as a neurotransmitter.
    1. biogenic amine
    2. amino acid
    3. gas
    4. catecholamine
    5. neuroactive peptide

13

75. Which of the following chemicals is NOT a known neurotransmitter?
    1. nitric oxide
    2. substance P
    3. ATP
    4. acetylcholine
    5. carbon dioxide

76. What chemical targets CB1 receptors?
    1. carbonic acid
    2. enkephalin
    3. tetrahydrocannabinol
    4. carbon dioxide
    5. glutamate
77. Which of the following neurotransmitters is a neuropeptide?
    1. glycine
    2. norepinephrine
    3. substance P
    4. aspartate
    5. acetylcholine
78. Which of the following neurotransmitters is an amino acid neurotransmitter released at excitatory synapses?
    1. norepinephrine
    2. aspartate
    3. acetylcholine
    4. glycine
    5. substance P
79. Which of the following neurotransmitters is a catecholamine?
    1. acetylcholine
    2. substance P
    3. aspartate
    4. norepinephrine
    5. glycine
80. Which of the following neurotransmitters is a biogenic amine, but not a catecholamine?
    1. acetylcholine
    2. norepinephrine
    3. aspartate
    4. serotonin
    5. substance P

14

81. Which of the following neurotransmitters is an amino acid neurotransmitter released at inhibitory synapses?
    1. glycine
    2. acetylcholine
    3. norepinephrine
    4. substance P
    5. aspartate
82. Which of the following neurotransmitters is the most common neurotransmitter in the peripheral nervous system?
    1. aspartate
    2. glycine
    3. substance P
    4. acetylcholine
    5. norepinephrine
83. What happens to the resting membrane potential of -70 mV when sodium channels open?
    1. repolarization
    2. returns to -70 mV
    3. membrane stabilization
    4. depolarization

83. 5. hyperpolarization
84. What happens to the resting membrane potential of -70 mV when sodium leak channels close?
    1. returns to -70 mV
    2. membrane stabilization
    3. repolarization
    4. hyperpolarization
    5. depolarization
85. What happens to the resting membrane potential of -70 mV when potassium channels open?
    1. repolarization
    2. hyperpolarization
    3. membrane stabilization
    4. depolarization
    5. returns to -70 mV
86. What happens to the resting membrane potential of -70 mV when potassium channels close?
    1. hyperpolarization
    2. depolarization
    3. returns to -70 mV
    4. membrane stabilization
    5. repolarization

15

87. What happens to the resting membrane potential of -70 mV when channels for an anion with an equilibrium potential of -80 mV open?
    1. membrane stabilization
    2. repolarization
    3. returns to -70 mV
    4. depolarization
    5. hyperpolarization
88. What happens to the resting membrane potential of -70 mV when channels for a cation with an equilibrium potential of -80 mV open?
    1. returns to -70 mV
    2. depolarization
    3. repolarization
    4. hyperpolarization
    5. membrane stabilization
89. What happens to the resting membrane potential of -70 mV when channels for a cation with an equilibrium potential of -30 mV open?
    1. membrane stabilization
    2. hyperpolarization
    3. depolarization
    4. repolarization
    5. returns to -70 mV
90. What happens to the resting membrane potential of -70 mV when channels, that permit both sodium and potassium to move through, open?
    1. hyperpolarization
    2. membrane stabilization
    3. depolarization
    4. returns to -70 mV
    5. repolarization

91. Which enzyme catalyzes the synthesis of cAMP?
    1. acetylcholinesterase
    2. choline acetyl transferase
    3. adenylate cyclase
    4. monoamine oxidase
    5. catechol-O-methyltransferase

16

92. Which enzyme catalyzes the synthesis of acetylcholine?
    1. adenylate cyclase
    2. catechol-O-methyltransferase
    3. acetylcholinesterase
    4. monoamine oxidase
    5. choline acetyl transferase
93. What enzyme catalyzes breakdown of catecholamines in the synaptic cleft and in the mitochondria of the axon terminal of the presynaptic cell?
    1. adenylate cyclase
    2. choline acetyl transferase
    3. acetylcholinesterase
    4. catechol-O-methyltransferase
    5. monoamine oxidase
94. What enzyme catalyzes breakdown of catecholamines in the synaptic cleft only?
    1. monoamine oxidase
    2. adenylate cyclase
    3. choline acetyl transferase
    4. catechol-O-methyltransferase
    5. acetylcholinesterase
95. What enzyme catalyzes breakdown of acetylcholine?
    1. catechol-O-methyltransferase
    2. monoamine oxidase
    3. acetylcholinesterase
    4. choline acetyl transferase
    5. adenylate cyclase
96. All of the following receptor sub-types are metabotropic, EXCEPT
    1. nicotinic cholinergic.
    2. alpha adrenergic.
    3. NMDA
    4. beta adrenergic.
    5. muscarinic cholinergic.
97. All of the following receptor sub-types are ionotropic, EXCEPT
    1. nicotinic cholinergic.
    2. kainate glutamatergic.
    3. AMPA glutamatergic.
    4. muscarinic cholinergic.
    5. GABAA  17

Figure 8.1

98. What is occurring in Step 2 of Figure 8.1, and how is that process originated?
    1. receptor that can stimulate a cellular response by gating its ion channel : stimulating a G protein to gate an ion channel

1. 2. influx of calcium : depolarization causes voltage-gated calcium channels to open
   3. remove neurotransmitter from the synaptic cleft : reuptake
   4. fast receptor opens an ion channel that is part of the receptor : reuptake
   5. slow receptor can open or close an ion channel by G protein coupling between receptor and ion channel : neurotransmitter release

99. Identify the structure on the postsynaptic membrane that bind with the neurotransmitter in Step 4 of Figure 8.1, and indicate its function.
    1. endocytotic vesicle storing neurotransmitter
    2. transporter for the reuptake of released neurotransmitter
    3. a receptor that can stimulate a cellular response by gating its ion channel or stimulating a G protein to gate an ion channel
    4. an enzyme used to remove neurotransmitter from the synaptic cleft
    5. a voltage-gated calcium channel for reuptake of Ca2+
100. Identify the structure on the postsynaptic membrane that binds with the neurotransmitter in Step 6 of Figure 8.1, and indicate its function.

1. an enzyme used to remove neurotransmitter from the synaptic cleft
2. a receptor that can stimulate a cellular response by gating its ion channel or stimulating a G protein to gate an ion channel
3. transporter for the reuptake of released neurotransmitter
4. a voltage-gated calcium channel for reuptake of Ca2+
5. endocytotic vesicle storing neurotransmitter

18

101. In Figure 8.1, the overall function of Steps 6-8, which occur simultaneously, is to

1. reuptake Ca2+.
2. remove neurotransmitter from the synaptic cleft.
3. release excess neurotransmitter.
4. stimulate a cellular response by gating its ion channel or stimulating a G protein to gate an ion channel.
5. create endocytotic vesicles for storing neurotransmitter.

102. In Figure 8.1, if the presynaptic neuron is cholinergic, what is the structure in Step 6?

1. acetylcholinesterase
2. choline acetyl transferase
3. dopa decarboxylase
4. catechol-O-methyltransferase
5. monoamine oxidase

103. In Figure 8.1, if the presynaptic neuron is adrenergic, what is the structure in Step 6?

1. acetylcholinesterase
2. monoamine oxidase or catechol-O-methyltransferase
3. choline acetyl transferase
4. dopa decarboxylase
5. phosphodiesterase

104. In Figure 8.1, what is the event in Step 1 that is required to start the process that leads to the release of neurotransmitter from an axon terminal?

1. movement of sodium into the neuron and down the axon
2. action potential
3. migration of newly synthesized neurotransmitter from the soma
4. movement of calcium down the axon
5. generator potential from the axon hillock

105. In Figure 8.1, what is going on in Step 3?

1. phagocytosis of calcium and its subsequent release
2. calcium is metabolized and packaged into secretory vesicles
3. calcium activation of pro-neurohormone
4. diffusion of neurotransmitter across the synaptic cleft before binding to the receptor on the postsynaptic membrane
5. the migration of the vesicle containing neurotransmitter to the cell membrane and its release by exocytosis

 19

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

1. voltage-gated sodium channels
2. voltage-gated potassium channels
3. voltage-gated cholinergic channels
4. voltage-gated calcium channels
5. voltage-gated adrenergic channels

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

A) magnesium B) calcium C) potassium D) hydrogen E) sodium

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

A) potassium B) hydrogen C) calcium D) sodium E) magnesium

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

1. ATP
2. Acetylcholine
3. Acetyl
4. Choline
5. DOPA

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

1. alpha and beta1
2. alpha1 and beta
3. beta2
4. alpha2 and beta1, beta2
5. alpha3

111. What is the type of receptor present on the axon terminal that responds to the release of neurotransmitter from that same axon terminal?

1. paracrine receptor
2. reuptake receptor
3. short loop receptor
4. autoreceptor
5. nociceptor

112. Information travels through the nervous system along the axons as action potentials. These action potentials must be transmitted across the synaptic cleft. Describe the process whereby an action potential that has

entered the axon terminal is able to induce a change in membrane potential in the postsynaptic membrane, following neurotransmitter binding to a metabotropic receptor.

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

114. Postsynaptic potentials, generated by neurotransmitter binding to receptors on the postsynaptic membrane can be excitatory or inhibitory. Describe inhibitory postsynaptic potentials and how chloride channels can be inhibitory without producing an IPSP.
115. Once an action potential reaches the axon terminal, that depolarization stimulates the release of neurotransmitters that can be modulated by other neurons that synapse with the axon terminal. Describe how neurotransmitters are released from the axon terminal and how that response is altered by axoaxonic synapses.
116. The neurotransmitter for skeletal muscle is acetylcholine which binds to nicotinic receptors on skeletal muscle. Describe the process whereby acetylcholine is synthesized, released, and degraded within the synapse.
117. Catecholamines are an important class of neurotransmitter. Describe the receptors involved in responding to catecholamines and how they are degraded.
118. Describe the process of neural integration in neurons, with particular emphasis on summation and how action potentials are generated within neurons.
119. A number of modified epithelial cells, acting as sensory receptors, innervate a single neuron. Some of these cells release excitatory neurotransmitters, while others release inhibitory neurotransmitters. How are these responses integrated by the neuron to determine whether an action potential will be generated or not?
120.  (Opening / Closing) of a potassium channel results in an excitatory postsynaptic potential.
121. 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 thereby (exciting / inhibiting) the neuron.
122. 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)
123. 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).
124. Temporal summation is less likely to occur when the receptor that has been activated is a (fast / slow) receptor.