Mechanisms Of Direct Synaptic Ch.11 Full Test Bank 6e

Chapter 11: Mechanisms of Direct Synaptic Transmission

Test Bank

Type: multiple choice question

Title: Chapter 11 Question 01

1. How does information transfer occur at electrical synapses?

Feedback: Subhead: Synaptic Transmission

Learning Objective: Distinguish between chemical transmission and electrical transmission.

Bloom’s Level: 3. Applying

a. Electrical depolarization of the nerve terminal leads to current flow directly from the presynaptic cell to the postsynaptic cell through connexons (or gap junctions).

b. Electrical depolarization of the nerve terminal causes presynaptic calcium channels to open, leading to the direct excitation of the postsynaptic cell.

c. Electrical depolarization of the nerve terminal causes the release of chemicals that open postsynaptic ligand-gated ion channels which pass current, depolarizing the postsynaptic cell.

d. Electrical depolarization of the nerve terminal directly opens postsynaptic ligand-gated ion channels, which pass current, depolarizing the postsynaptic cell.

e. Electrical depolarization of the nerve terminal leads to current flow directly from the presynaptic cell to the postsynaptic cell through voltage-gated ion channels.

Type: multiple choice question

Title: Chapter 11 Question 02

2. How does information transfer occur at chemical synapses?

Feedback: Section: Synaptic Transmission

Learning Objective: Distinguish between chemical transmission and electrical transmission.

Bloom’s Level: 3. Applying

a. Electrical depolarization of the nerve terminal leads to current flow directly from the presynaptic cell to the postsynaptic cell through connexons (or gap junctions).

b. Electrical depolarization of the nerve terminal causes presynaptic calcium channels to open, leading to the direct excitation of the postsynaptic cell.

c. Electrical depolarization of the nerve terminal causes the release of chemicals that open postsynaptic ligand-gated ion channels which pass current, depolarizing the postsynaptic cell.

d. Electrical depolarization of the nerve terminal directly opens postsynaptic ligand-gated ion channels, which pass current, depolarizing the postsynaptic cell.

e. Electrical depolarization of the nerve terminal leads to current flow directly from the presynaptic cell to the postsynaptic cell through voltage-gated ion channels.

Type: multiple choice question

Title: Chapter 11 Question 03

3. Following years of debate about chemical vs. electrical transmission at synapses in the brain, which form of transmission was found to exist?

Feedback: Subhead: Synaptic Transmission

Learning Objective: Distinguish between chemical transmission and electrical transmission.

Bloom’s Level: 2. Understanding

a. All neurons in the brain were found to use electrical transmission.

b. All neurons in the brain were found to use chemical transmission.

c. Some neurons in the brain were found to use electrical transmission, others chemical transmission, and some both forms of transmission.

d. All neurons in the brain were found to initially use chemical transmission, and then convert to electrical transmission.

e. All neurons in the brain were found to initially use electrical transmission, and then convert to chemical transmission.

Type: multiple choice question

Title: Chapter 11 Question 04

4. Dendritic spines are commonly a site for

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the structure of electrical synapses and of chemical synapses.

Bloom’s Level: 2. Understanding

a. both excitatory and inhibitory synaptic transmission.

b. inhibitory synaptic transmission.

c. excitatory synaptic transmission.

d. storage of transmitter molecules.

e. active zones.

Type: multiple choice question

Title: Chapter 11 Question 05

5. Which of the following does not exist at a direct chemical synapse?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the structure of electrical synapses and of chemical synapses.

Bloom’s Level: 1. Remembering

a. Synaptic vesicles

b. 30 nm synaptic cleft

c. Postsynaptic ligand gated ion channel receptors

d. Connexon proteins (gap junctions)

e. Active zones

Type: multiple choice question

Title: Chapter 11 Question 06

6. What is the “synaptic cleft”?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the structure of electrical synapses and of chemical synapses.

Bloom’s Level: 1. Remembering

a. The nerve terminal

b. The postsynaptic collection of receptors

c. The space between the presynaptic neuron and the postsynaptic cell

d. The postsynaptic change in membrane potential

e. The active zone

Type: multiple choice question

Title: Chapter 11 Question 07

7. At the NMJ, postjunctional folds radiate into the muscle fiber from the cleft at

regular intervals. What is their role at neuromuscular synapses?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the structure of electrical synapses and of chemical synapses.

Bloom’s Level: 2. Understanding

a. Binding transmitter molecules

b. Increasing the postsynaptic surface area for receptors

c. Reducing the space between the presynaptic and postsynaptic cells

d. Increasing the space between presynaptic and postsynaptic cells

e. Degrading transmitter after binding to receptors

Type: multiple choice question

Title: Chapter 11 Question 08

8. How does acetycholinesterase function at synapses that release acetylcholine?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the structure of electrical synapses and of chemical synapses.

Bloom’s Level: 2. Understanding

a. It is a postsynaptic muscarinic receptor blocker.

b. It is a postsynaptic nicotinic receptor blocker.

c. It is a synaptic cleft enzyme that breaks down acetylcholine receptor proteins.

d. It is a presynaptic calcium channel agonist.

e. It is a synaptic cleft enzyme that breaks down the transmitter acetylcholine.

Type: multiple choice question

Title: Chapter 11 Question 09

9. How do transmitters act on the postsynaptic cell at direct chemical synapses?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the structure of electrical synapses and of chemical synapses.

Bloom’s Level: 2. Understanding

a. They diffuse across postsynaptic membranes to excite postsynaptic cells.

b. They bind to voltage-gated ion channels to induce postsynaptic current flux.

c. They bind to metabotropic receptors to induce postsynaptic biochemical changes.

d. They bind to ligand-gated ion channels to induce postsynaptic current flux.

e. They bind to extracellular matrix molecules to excite postsynaptic cells.

Type: multiple choice question

Title: Chapter 11 Question 10

10. Synaptic vesicles are concentrated in large numbers within nerve terminals. What is their function?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the role of synaptic vesicles in chemical transmission.

Bloom’s Level: 2. Understanding

a. They have no known function.

b. They engulf foreign proteins for degradation.

c. They fuse with mitochondria to transport ATP.

d. They store and deliver active zone proteins to the plasma membrane.

e. They store and release chemical transmitter molecules.

Type: multiple choice question

Title: Chapter 11 Question 11

11. What is an endplate potential?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 3. Applying

a. The membrane potential that a nerve terminal will release transmitter.

b. The membrane potential that a postsynaptic muscle cell will reach threshold.

c. Depolarization of the endplate region of the muscle fiber following acetylcholine binding to postsynaptic nicotinic acetylcholine receptors.

d. Hyperpolarization of the endplate region of the muscle fiber following acetylcholine binding to postsynaptic nicotinic acetylcholine receptors.

e. Depolarization of the endplate region of the muscle fiber following acetylcholine binding to muscarinic receptors.

Type: multiple choice question

Title: Chapter 11 Question 12

12. How does the size and shape of the endplate potential change when recorded at different distances from the endplate at the NMJ?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 4. Analyzing

a. The EPP does not change when recorded at different distances from the NMJ.

b. The EPP has the same amplitude but has a slower time course when recorded at increasing distances from the NMJ.

c. The EPP has reduced amplitude but the same time course when recorded at increasing distances from the NMJ.

d. The EPP has both a reduced amplitude and slower time course when recorded at increasing distances from the NMJ.

e. The EPP has both an increased amplitude and slower time course when recorded at increasing distances from the NMJ.

Type: multiple choice question

Title: Chapter 11 Question 13

13. An inhibitory postsynaptic potential (IPSP) occurs when

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 2. Understanding

a. the ligand-gated ion channels with a reversal potential that is more negative than membrane potential open in the postsynaptic membrane in response to transmitter binding.

b. the ligand-gated ion channels with a reversal potential that is more positive than membrane potential open in the postsynaptic membrane in response to transmitter binding.

c. metabotropic receptors are activated by transmitter binding.

d. voltage-gated ion channels open during an action potential.

e. the ligand-gated ion channels without a reversal potential open in the postsynaptic membrane in response to transmitter binding.

Type: multiple choice question

Title: Chapter 11 Question 14

14. Why does the plant alkaloid nicotine cause skeletal muscle contraction?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 4. Analyzing

a. Nicotine causes presynaptic action potentials.

b. Nicotine blocks postsynaptic nicotinic acetylcholine receptors.

c. Nicotine is an agonist at postsynaptic muscarinic acetylcholine receptors.

d. Nicotine is an agonist at postsynaptic nicotinic acetylcholine receptors.

e. Nicotine increases presynaptic calcium channel function, increasing transmitter release.

Type: multiple choice question

Title: Chapter 11 Question 15

15. How do acetycholinesterase drugs (i.e. physostigmine) alter EPPs?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 2. Understanding

a. Physostigmine prolongs the time course of EPPs.

b. Physostigmine blocks EPPs.

c. Physostigmine shortens the time course of EPPs.

d. Physostigmine has no effect on EPPs.

e. Physostigmine prevents the transmitter release that causes EPPs.

Type: multiple choice question

Title: Chapter 11 Question 16

16. What determines the decay time for an endplate potential?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 5. Evaluating

a. The time course of acetylcholine release from the nerve terminal

b. The time that acetylcholine is present in the synaptic cleft

c. The time constant of the presynaptic nerve cell membrane

d. The mean open time of the acetylcholine receptor channel

e. The time constant of the muscle fiber membrane

Type: multiple choice question

Title: Chapter 11 Question 17

17. What is the subunit composition of the NMDA receptor?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 1. Remembering

a. Four GluN1 subunits arranged as a tetramer

b. Four GluN2 subunits arranged as a tetramer

c. Two GluN1 subunits and three GluN2 subunits, arranged as a pentamer

d. Three GluN1 subunits and two GluN2 subunits, arranged as a pentamer

e. Two GluN1 subunits and two GluN2 subunits, arranged as a tetramer

Type: multiple choice question

Title: Chapter 11 Question 18

18. What are the three types of ionotropic glutamate receptors?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 1. Remembering

a. Nicotinic, muscarinic, and kainate

b. Kainate, AMPA, and nicotinic

c. AMPA, NMDA, and nicotinic

d. Kainate, AMPA, and NMDA

e. Kainate, NMDA, and nicotinic

Type: multiple choice question

Title: Chapter 11 Question 19

19. The NMDA type of glutamate ionotropic receptor requires two agonists to be bound to activate this receptor. What are these two agonists?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 1. Remembering

a. Glutamate and acetylcholine

b. Glutamate and Glycine or D-serine

c. Glycine and D-serine

d. Glycine and acetylcholine

e. D-serine and acetylcholine

Type: multiple choice question

Title: Chapter 11 Question 20

20. If you record EPSCs with a patch electrode from an interneuron in the

CA1 region of a rat hippocampal slice preparation and hold the postsynaptic membrane potential at -80 mV, why is the response not sensitive to blockers of NMDA receptors?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 5. Evaluating

a. There are no NMDA receptors at these synapses.

b. At -80 mV, AMPA receptors are blocked by magnesium.

c. At -80 mV, NMDA receptors do not bind glutamate.

d. At -80 mV, NMDA receptors are blocked by magnesium.

e. At -80 mV, NMDA receptors do not bind glycine or D-serine.

Type: multiple choice question

Title: Chapter 11 Question 21

21. Under which of the following conditions would you expect NMDA receptors to contribute to postsynaptic currents in the hippocampus?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 3. Applying

a. Following a single presynaptic action potential

b. Following a train of presynaptic action potentials at high frequency

c. At resting membrane potential

d. After hyperpolarization of the postsynaptic membrane

e. When ionotropic GABA receptors are also activated

Type: multiple choice question

Title: Chapter 11 Question 22

22. What is a competitive antagonist?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the technique of ionophoresis and how it is applied.

Bloom’s Level: 2. Understanding

a. An inhibitor ligand for a receptor that shares its binding site with the natural activating ligand

b. An agonist ligand for a receptor that shares its binding site with the natural activating ligand

c. An inhibitor ligand for a receptor that does not affect the natural activating ligand’s ability to bind the receptor

d. An agonist ligand for a receptor that does not affect the natural activating ligand’s ability to bind the receptor

e. A receptor ligand that binds to a part of a receptor that is not involved in natural ligand binding

Type: multiple choice question

Title: Chapter 11 Question 23

23. How does the technique called ionophoresis work?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the technique of ionophoresis and how it is applied.

Bloom’s Level: 2. Understanding

a. Molecules inside a glass pipet can be expelled by pressure.

b. Molecules inside a glass pipet can be expelled by electrical charge.

c. Molecules inside a glass pipet can be expelled by simple diffusion.

d. Molecules inside a glass pipet can be expelled by suction.

e. Molecules inside a glass pipet can be expelled by concentration gradient.

Type: multiple choice question

Title: Chapter 11 Question 24

24. How are acetylcholine receptors distributed along the muscle membrane?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe the technique of ionophoresis and how it is applied.

Bloom’s Level: 4. Analyzing

a. They are at a uniform density all along the muscle membrane.

b. They are distributed in a gradual gradient that increases density gradually with distance away from the NMJ.

c. They are distributed in a gradual gradient that decreases density gradually with distance away from the NMJ.

d. They are highly concentrated directly under the presynaptic terminal at the NMJ.

e. There are no acetylcholine receptors on muscle membrane, only on the nerve terminal at the NMJ.

Type: multiple choice question

Title: Chapter 11 Question 25

25. How does acetylcholine binding to nicotinic receptors alter the permeability of the muscle membrane?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe two techniques used to assess the permeability changes produced by acetylcholine.

Bloom’s Level: 2. Understanding

a. The permeability of the postsynaptic membrane is increased to sodium, potassium, and calcium, but not to chloride.

b. The permeability of the postsynaptic membrane is increased to sodium, but not to potassium, calcium, and chloride.

c. The permeability of the postsynaptic membrane is increased to sodium, potassium, calcium, and chloride.

d. The permeability of the postsynaptic membrane is increased to potassium, but not to sodium, calcium, and chloride.

e. The permeability of the postsynaptic membrane is increased to calcium but not to sodium, potassium, and chloride.

Type: multiple choice question

Title: Chapter 11 Question 26

26. What is responsible for the time course of decay of the endplate current recorded at the neuromuscular junction?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe two techniques used to assess the permeability changes produced by acetylcholine.

Bloom’s Level: 5. Evaluating

a. The time that acetylcholine is bound to the acetylcholine receptor.

b. The mean open time of the presynaptic calcium channel that triggers acetylcholine release.

c. The time course of synaptic vesicle endocytosis at the presynaptic nerve terminal.

d. The mean open time of the acetylcholine receptor channel.

e. The mean open time of the postsynaptic voltage-gated sodium channel.

Type: multiple choice question

Title: Chapter 11 Question 27

27. Why do single channel measurements of acetylcholine receptor currents show that all channel openings reach the same amplitude?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe two techniques used to assess the permeability changes produced by acetylcholine.

Bloom’s Level: 5. Evaluating

a. When the acetylcholine receptor channel is in the open state, the pore conducts the same amount of current due to the permeation properties of that channel.

b. Acetylcholine receptor channels have the same mean open time.

c. Acetylcholine receptors bind two molecules of acetylcholine.

d. Acetylcholine receptor channels have the same probability of opening.

e. Acetylcholine receptor channels have the same desensitization rate.

Type: multiple choice question

Title: Chapter 11 Question 28

28. How many acetylcholine molecules have to bind to the muscle nicotinic acetylcholine receptor to maximally activate this ionotropic receptor channel?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Describe two techniques used to assess the permeability changes produced by acetylcholine.

Bloom’s Level: 1. Remembering

a. 0

b. 1

c. 2

d. 3

e. 4

Type: multiple choice question

Title: Chapter 11 Question 29

29. Which technique can be used to determine the specific conductance changes in the muscle membrane, and their voltage dependence, after acetylcholine binds to nicotinic receptors?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Explain what the reversal potential is and discuss its significance.

Bloom’s Level: 3. Applying

a. Microelectrode recordings

b. Voltage clamp experiments

c. Measurement of the movement of radioactive isotopes across the cell membrane

d. Fluorescence microscopy

e. Gel electrophoresis

Type: multiple choice question

Title: Chapter 11 Question 30

30. What is the reversal potential for a channel?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Explain what the reversal potential is and discuss its significance.

Bloom’s Level: 2. Understanding

a. The membrane potential at which the net current flux through a channel is zero, and on either side of which the net current flux moves in opposite directions

b. The membrane potential at which the net current flux through a channel is outward

c. The membrane potential at which the net current flux through a channel is inward

d. The membrane potential of the presynaptic neuron that triggers an action potential

e. The membrane potential of the presynaptic neuron that triggers transmitter release

Type: multiple choice question

Title: Chapter 11 Question 31

31. What would happen to the synaptic potential amplitude caused by an ionotropic receptor in a postsynaptic neuron (e.g. glutamate-mediated EPSP) if the input resistance of the postsynaptic membrane was decreased?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Explain what the reversal potential is and discuss its significance.

Bloom’s Level: 5. Evaluating

a. There would be no change in the synaptic potential amplitude.

b. The synaptic potential would become larger in amplitude.

c. The synaptic potential would become smaller in amplitude.

d. The synaptic potential would be blocked.

e. The synaptic potential would reverse in polarity.

Type: multiple choice question

Title: Chapter 11 Question 32

32. At the frog neuromuscular junction, when you block voltage-gated sodium channels selectively in muscle (but not nerve), and then record EPPs (using the microelectrode technique) in response to repeated low frequency nerve stimulation, you see EPPs that are very large (each depolarizes muscle membrane above resting potential to about -30 mV), but these EPPS do not fluctuate significantly when you compare the size of each EPP. Why do these EPPs not vary significantly in amplitude?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Explain what the reversal potential is and discuss its significance.

Bloom’s Level: 6. Creating

a. This very large EPP is above threshold and an action potential is evoked which is all-or-none and thus does not show amplitude fluctuations.

b. This very large EPP depolarizes the cell so much that the peak of the EPP is near the reversal potential for the voltage-gated sodium channel.

c. This very large EPP depolarizes the cell so much that the peak of the EPP is near the reversal potential for the acetylcholine receptor channel.

d. The very large EPP is caused by the release of a fixed large number of transmitter molecules that are not packaged into vesicles.

e. The very large EPP is caused by the release of a fixed number of synaptic vesicles released and this number of vesicles does not change with each stimulation.

Type: multiple choice question

Title: Chapter 11 Question 33

33. The reversal potential for the nicotinic acetylcholine receptor is about -15 mV because it is determined by its selective permeability for

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: Explain what the reversal potential is and discuss its significance.

Bloom’s Level: 4. Analyzing

a. sodium ions.

b. potassium ions.

c. sodium and potassium ions.

d. sodium, calcium, and potassium ions.

e. calcium ions.

Type: multiple choice question

Title: Chapter 11 Question 34

34. Which two synaptic specializations are present at neuromuscular synapses, but not at CNS synapses?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: State two important differences between neuromuscular and CNS synapses.

Bloom’s Level: 1. Remembering

a. Postjunctional folds and Schwann cells

b. Synaptic vesicles and active zones

c. Glial cell wrapping and mitochondria

d. Postjunctional folds and mitochondria

e. Postjunctional folds and active zones

Type: multiple choice question

Title: Chapter 11 Question 35

35. What is the principal excitatory transmitter in the CNS?

Feedback: Subhead: Chemical Synaptic Transmission

Learning Objective: State two important differences between neuromuscular and CNS synapses.

Bloom’s Level: 1. Remembering

a. Acetylcholine

b. Glutamate

c. GABA

d. Glycine

e. D-serine

Type: multiple choice question

Title: Chapter 11 Question 36

36. What happens to the reversal potential for IPSPs when chloride is injected into an adult neuron to increase the cytoplasmic concentration of chloride?

Feedback: Subhead: Direct Chemical Synaptic Inhibition

Learning Objective: Describe how direct chemical synaptic inhibition differs from direct chemical synaptic excitation.

Bloom’s Level: 5. Evaluating

a. The reversal potential does not change.

b. The reversal potential becomes more positive.

c. The reversal potential becomes more negative.

d. The reversal potential is zero millivolts.

e. The reversal potential is not affected by the chloride concentration in the cytoplasm.

Type: multiple choice question

Title: Chapter 11 Question 37

37. What is the reversal potential for an IPSP in an adult neuron?

Feedback: Subhead: Direct Chemical Synaptic Inhibition

Learning Objective: Describe how direct chemical synaptic inhibition differs from direct chemical synaptic excitation.

Bloom’s Level: 3. Applying

a. Near the threshold for firing an action potential

b. Near the voltage that action potentials reach at their peak

c. Near the neuron resting potential

d. Near zero millivolts

e. IPSPs do not have a reversal potential.

Type: multiple choice question

Title: Chapter 11 Question 38

38. In embryonic neurons, activation of ionotropic GABA or glycine receptors results in

Feedback: Subhead: Direct Chemical Synaptic Inhibition

Learning Objective: Explain how direct chemical synaptic inhibition occurs.

Bloom’s Level: 3. Applying

a. inward movement of chloride, which leads to hyperpolarization.

b. outward movement of chloride, which leads to hyperpolarization.

c. inward movement of chloride, which leads to depolarization.

d. outward movement of chloride, which leads to depolarization.

e. no net movement of chloride, which does not change membrane potential.

Type: multiple choice question

Title: Chapter 11 Question 39

39. If one impales a neuron with two different intracellular microelectrodes, one to measure membrane potential and a second to pass brief hyperpolarizing current pulses into the cell, why does the size of the measured changes in membrane potential caused by the current pulses decrease when transmitter binds to an ionotropic receptor?

Feedback: Subhead: Direct Chemical Synaptic Inhibition

Learning Objective: Explain how direct chemical synaptic inhibition occurs.

Bloom’s Level: 3. Applying

a. The ionotropic receptor inhibits a voltage-gated sodium channel.

b. The ionotropic receptor inhibits a voltage-gated potassium channel.

c. The input resistance of the cell does not change when ionotropic receptor channels open.

d. The input resistance of the cell decreases when ionotropic receptor channels open.

e. The input resistance of the cell increases when ionotropic receptor channels open.

Type: multiple choice question

Title: Chapter 11 Question 40

40. In adult neurons, activation of ionotropic GABA or glycine receptors results in

Feedback: Subhead: Direct Chemical Synaptic Inhibition

Learning Objective: Explain how direct chemical synaptic inhibition occurs.

Bloom’s Level: 3. Applying

a. inward movement of chloride, which leads to hyperpolarization.

b. outward movement of chloride, which leads to hyperpolarization.

c. inward movement of chloride, which leads to depolarization.

d. outward movement of chloride, which leads to depolarization.

e. no net movement of chloride, which does not change membrane potential.

Type: multiple choice question

Title: Chapter 11 Question 41

41. Presynaptic inhibition is caused by

Feedback: Subhead: Direct Chemical Synaptic Inhibition

Learning Objective: Explain what presynaptic inhibition is and how its function differs from that of postsynaptic inhibition.

Bloom’s Level: 2. Understanding

a. inward movement of chloride, which leads to hyperpolarization.

b. outward movement of chloride, which leads to depolarization.

c. an increase in the amount of transmitter released from excitatory nerve terminals.

d. a reduction in the amount of transmitter released from excitatory nerve terminals.

e. both an inward movement of chloride, which leads to hyperpolarization and a reduction in the amount of transmitter released from excitatory nerve terminals.

Type: multiple choice question

Title: Chapter 11 Question 42

42. When electrical synapses are said to be “rectifying,” it means they

Feedback: Subhead: Electrical Synaptic Transmission

Learning Objective: Explain what rectification is.

Bloom’s Level: 2. Understanding

a. do not conduct ions in either direction.

b. conduct ions equally well in both directions.

c. conduct ions more strongly in one direction than the other.

d. cause only excitation.

e. cause only inhibition.

Type: multiple choice question

Title: Chapter 11 Question 43

43. What does an electrical coupling ratio of 1:6 mean?

Feedback: Subhead: Electrical Synaptic Transmission

Learning Objective: Discuss how electrical transmission and chemical transmission complement one another.

Bloom’s Level: 2. Understanding

a. The presynaptic and postsynaptic cells are not electrically coupled.

b. One out of six cells are electrically coupled.

c. One out of six cells are not electrically coupled.

d. One-Sixth of the postsynaptic voltage change appears in the presynaptic cell.

e. One-Sixth of the presynaptic voltage change appears in the postsynaptic cell.

Type: essay/short answer question

Title: Chapter 11 Question 44

44. In the late 1800s, explain why the hypothesis that neurons in the brain communicated with one another by chemical transmitter release was not generally accepted.

Feedback: The idea of chemicals being used to communicate between neurons seems unlikely in the 1800s because people knew that communication in the CNS was very fast and could not envision how chemicals could work this quickly. Further, transmission within the CNS was only able to be studied using electrical recording techniques, which led people to focus on direct electrical communication.

Subhead: Synaptic Transmission

Learning Objective: State two reasons why it took scientists so long to accept the idea of chemical transmission.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 11 Question 45

45. If two postsynaptic neurons both receive the same synaptic current, but neuron 1 has a much lower resting conductance than neuron 2, which neuron will experience a larger change in membrane potential cause by the synaptic current, and why?

Feedback: Neuron 1 will experience a larger change in membrane potential. This is because the much lower resting conductance of Neuron 1 indicates that the input resistance is higher, and as governed by Ohm’s Law (V=IR), the higher resistance (R) with the same synaptic current (I) will result in a larger change in membrane potential (V).

Subhead: Synaptic Transmission

Learning Objective: State two reasons why it took scientists so long to accept the idea of chemical transmission.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 11 Question 46

46. Explain the voltage-sensitivity of the NMDA type of ionotropic glutamate receptors.

Feedback: At resting membrane potential, the NMDA receptor channel is blocked by magnesium ions. As a result, if glutamate binds to the NMDA receptor at resting membrane potential, there will be no current flux. However, when the membrane is depolarized, the magnesium block is relieved and glutamate binding to the NMDA receptor leads to current flux through the channel. The more the membrane is depolarized, the greater the percentage of NMDA receptor channels that are unblocked and available to conduct current.

Subhead: Chemical Synaptic Transmission

Learning Objective: Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 11 Question 47

47. Explain how changes in the developmental expression of different chloride transporters alters the synaptic potential caused by ligand-gated chloride channels that are activated by GABA or Glycine.

Feedback: In embryonic neurons, chloride is transported into the neuron by a sodium–

potassium–2-chloride cotransporter (NKCC), generating a high intracellular chloride

concentration. Under these conditions, activation of chloride channels by GABA

or glycine results in outward movement of chloride and depolarization. In adult neurons, another transporter, a potassium–chloride cotransporter (KCC2), is expressed and pumps chloride out of the cell. Under these conditions, GABA or glycine will hyperpolarize the cell.

Subhead: Direct Synaptic Inhibition

Learning Objective: Explain how direct chemical synaptic inhibition occurs.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 11 Question 48

48. Describe the mechanism by which auto-inhibition alters synapse function.

Feedback: Auto-inhibition occurs when transmitter that is released by a nerve terminal acts back onto receptors of that nerve terminal. These presynaptic receptors are often metabotropic and act to reduce subsequent transmitter release from the nerve terminal.

Subhead: Direct Chemical Synaptic Inhibition

Learning Objective: Explain how direct chemical synaptic inhibition occurs.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 11 Question 49

49. Describe the different functions for presynaptic vs. postsynaptic inhibition.

Feedback: Postsynaptic inhibition alters ion channel function and reduces the excitability of the postsynaptic cell, rendering it relatively less responsive to all excitatory inputs. Presynaptic inhibition is much more specific and targets particular presynaptic nerve terminals. This reduces transmitter release from these particular synapses but does not affect other neighboring synapses.

Subhead: Direct Chemical Synaptic Inhibition

Learning Objective: Explain what presynaptic inhibition is and how its function differs from that of postsynaptic inhibition.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 11 Question 50

50. Explain the mechanisms that are used to concentrate acetylcholine receptors on the postsynaptic membrane of motor endplates.

Feedback: The protein Agrin is secreted by motor nerve terminals and binds to laminin, -dystroglycan, and the receptor tyrosin kinase MUSK to trigger the clustering of acetylcholine receptors. Once clustered, these receptors are bound to rapsyn and dystrophin in muscle cells to hold them in place.

Subhead: Transmitter Receptor Localization

Learning Objective: Explain why acetylcholine receptors (AChRs) are highly concentrated on motor end plates.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 11 Question 51

51. NMDA and AMPA subtypes of glutamate receptors are differentially regulated during synaptic plasticity, with AMPA receptors moving into or out of the postsynaptic density to alter the strength of chemical transmission. Explain how these two types of receptors are localized to postsynaptic sites of transmitter release and how these localization mechanisms might explain these differences in receptor movement.

Feedback: NMDA-type glutamate receptors bind to proteins of the PSD-95 family, while

AMPA-type glutamate receptors bind to proteins of the GRIP and PICK families. Therefore, they are anchored by different proteins. AMPA receptors turn over rapidly, and they are free to move in and out of the postsynaptic density by mechanisms that are likely coupled to their binding partners. In addition, the different binding partners alter the modulation of these receptors by recruiting different signaling proteins.

Subhead: Transmitter Receptor Localization

Learning Objective: Explain why acetylcholine receptors (AChRs) are highly concentrated on motor end plates.

Bloom’s Level: 5. Evaluating

Type: essay/short answer question

Title: Chapter 11 Question 52

52. When electrical synapses are found in the adult CNS, what have they been shown to useful for?

Feedback: Here are two examples. In cortex, electrical synapses couple many interneurons together to synchronize their activity. This is a mechanism that leads to synchronized oscillations in activity within these brain areas. In the retina, electrical coupling between horizontal cells extends their receptive field and enhances the ability to detect light under low light conditions.

Subhead: Electrical Synaptic Transmission

Learning Objective: Discuss how electrical transmission and chemical transmission complement one another.

Bloom’s Level: 5. Evaluating

Type: essay/short answer question

Title: Chapter 11 Question 53

53. How does Dopamine modulate electrical coupling in the retina?

Feedback: Light stimulates the release of dopamine from amacrine cells. This increases cAMP in horizontal cells, which activates cAMP-dependent protein kinase and phosphorylates connexins, resulting in a decrease in the gap junction conductance.

This change shrinks the receptive field of the horizontal cell. At night the opposite occurs to increasing the horizontal cell’s receptive field and enhancing the detection of dim objects.

Subhead: Electrical Synaptic Transmission

Learning Objective: List two places in vertebrate bodies where synapses with electrical transmission occur.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 11 Question 54

54. How are electrical synapses important creating synchronized oscillations of activity within the cortex?

Feedback: Synchronized oscillations occur in the cortex when large groups of neurons are active at the same time. Electrical synapses between interneurons in the cortex ensure that if one interneuron is active, the coupled neighbors will also be active. The synchronous activity of tens of interneurons can ensure that they all fire action potentials together and inhibit many excitatory neurons at the same time, creating a rhythm.

Subhead: Electrical Synaptic Transmission

Learning Objective: List two places in vertebrate bodies where synapses with electrical transmission occur.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 11 Question 55

55. Why is electrical transmission faster than chemical transmission?

Feedback: The 1 millisecond synaptic delay at a chemical synapse is due to the time taken for the terminal to release transmitter. This is much longer that is observed at electrical synapses. This is because electrical transmission occurs by direct intercellular current flow through channels that connect presynaptic and postsynaptic cells. This occurs much faster as there are no biochemical mechanisms required to mediate communication when ions can directly flow through channels between cells.

Subhead: Electrical Synaptic Transmission

Learning Objective: Explain why electrical transmission is faster than chemical transmission.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 11 Question 56

56. What determines the coupling ratio between electrically couple neurons?

Feedback: Electrical coupling between neurons depends not only on the number of connexons but also on their probability of opening. The more gap junction channels there are that are open, the higher the coupling ratio between cells because there are more pathways for charge movement between cells. This can be influenced by second messengers that phosphorylate connexins and alter their function.

Subhead: Electrical Synaptic Transmission

Learning Objective: Explain what a coupling ratio is.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 11 Question 57

57. Discuss how the presence of both electrical and chemical synaptic transmission can influence one another.

Feedback: When both chemical and electrical synapses are present in close proximity to one another, the change in membrane potential caused by the chemical synapse will be transmitted through the electrical synapse. In addition, the electrical coupling can create a current leak that can reduce the amplitude of any depolarization caused by a chemical synapse.

Subhead: Electrical Synaptic Transmission

Learning Objective: Discuss how electrical transmission and chemical transmission complement one another.

Bloom’s Level: 5. Evaluating

Type: essay/short answer question

Title: Chapter 11 Question 58

58. When electrical synapses are found in the adult CNS, what have they been shown to useful for?

Feedback: Here are two examples. In cortex, electrical synapses couple many interneurons together to synchronize their activity. This is a mechanism that leads to synchronized oscillations in activity within these brain areas. In the retina, electrical coupling between horizontal cells extends their receptive field and enhances the ability to detect light under low light conditions.

Subhead: Electrical Synaptic Transmission

Learning Objective: Discuss how electrical transmission and chemical transmission complement one another.

Bloom’s Level: 5. Evaluating

Type: essay/short answer question

Title: Chapter 11 Question 59

59. What are the advantages of electrical transmission?

Feedback: (1) Electrical synapses are more reliable than chemical synapses (less prone to disruption or modulation). (2) Electrical synapses are also able to transmit information faster than chemical synapses. Speed is important for rapid reflexes and escape responses. (3) Electrical synapses can synchronize the activity of large groups of neurons. (4) Electrical synapses can allow the direct transfer of second messenger molecules between the presynaptic and postsynaptic cell (including calcium, adenosine triphosphate (ATP), and cAMP.

Subhead: Electrical Synaptic Transmission

Learning Objective: State two advantages of electrical transmission over chemical transmission.

Bloom’s Level: 5. Evaluating