Question 1

Presynaptic inhibition is caused by

Accepted Answer

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. 
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.

Question 2

What is the principal excitatory transmitter in the CNS?

Accepted Answer

A)  Acetylcholine 
B)  Glutamate 
C)  GABA 
D)  Glycine 
E)  D-serine 
A)  Acetylcholine 
B)  Glutamate 
C)  GABA 
D)  Glycine 
E)  D-serine

Question 3

What is the "synaptic cleft"?

Accepted Answer

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 
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

Question 4

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

Accepted Answer

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. 
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.

Question 5

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

Accepted Answer

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. 
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.

Question 6

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

Accepted Answer

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. 
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.

Question 7

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?

Accepted Answer

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. 
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.

Question 8

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

Accepted Answer

A)  sodium ions. 
B)  potassium ions. 
C)  sodium and potassium ions. 
D)  sodium, calcium, and potassium ions. 
E)  calcium ions. 
A)  sodium ions. 
B)  potassium ions. 
C)  sodium and potassium ions. 
D)  sodium, calcium, and potassium ions. 
E)  calcium ions.

Question 9

How does the technique called ionophoresis work?

Accepted Answer

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. 
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.

Question 10

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

Accepted Answer

Auto-inhibition occurs when transmitter

Question 11

What is an endplate potential?

Accepted Answer

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. 
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.

Question 12

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

Accepted Answer

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. 
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.

Question 13

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

Accepted Answer

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. 
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.

Question 14

Describe the different functions for presynaptic vs. postsynaptic inhibition.

Accepted Answer

Postsynaptic inhibition alters ion chann

Question 15

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

Accepted Answer

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. 
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.

Question 16

How does information transfer occur at chemical synapses?

Accepted Answer

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. 
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.

Question 17

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

Accepted Answer

When both chemical and electrical synaps

Question 18

At the NMJ, postjunctional folds radiate into the muscle fiber from the cleft at
Regular intervals. What is their role at neuromuscular synapses?

Accepted Answer

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 
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

Question 19

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

Accepted Answer

Synchronized oscillations occur in the c

Question 20

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

Accepted Answer

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 
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

Exam 11: Mechanisms of Direct Synaptic Transmission

Presynaptic inhibition is caused by

What is the principal excitatory transmitter in the CNS?

What is the "synaptic cleft"?

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

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

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

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

How does the technique called ionophoresis work?

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

What is an endplate potential?

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

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

Describe the different functions for presynaptic vs. postsynaptic inhibition.

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

How does information transfer occur at chemical synapses?

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

At the NMJ, postjunctional folds radiate into the muscle fiber from the cleft at Regular intervals. What is their role at neuromuscular synapses?

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

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

Principles of Signaling and Organization

Signaling in the Visual System

Functional Architecture of the Visual Cortex

Ion Channels and Signaling

Structure of Ion Channels

Ionic Basis of the Resting Potential

Ionic Basis of the Action Potential

Electrical Signaling in Neurons

Ion Transport Across Cell Membranes

Properties and Functions of Neuroglial Cells

Indirect Mechanisms of Synaptic Transmission

Release of Neurotransmitters

Neurotransmitters in the Central Nervous System

Transmitter Synthesis, Storage, Transport, and Inactivation

Synaptic Plasticity

The Molecular and Cellular Biology of Synaptic Plasticity

Mechanisms of Extrasynaptic Communication

Autonomic Nervous System

Walking, Flying, and Swimming: Cellular Mechanisms of Sensorimotor Behavior in Invertebrates

Sensory Transduction

Transduction and Transmission in the Retina

Touch, Pain, and Texture Sensation

Auditory and Vestibular Sensation

Constructing Perception

Initiation and Control of Coordinated Muscular Movements

Development of the Nervous System

Critical Periods in Sensory Systems

Regeneration and Repair of Synaptic Connections After Injury

Appendix

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